title: Review: The effect of temperature on enzyme activity: new insights and their implications

authors: Daniel, Roy M.

subjects: Equilibrium Model

abstract: The two established thermal properties of enzymes are their activation energy and their thermal stability. Arising from careful measurements of the thermal behaviour of enzymes, a new model, the Equilibrium Model, has been developed to explain more fully the effects of temperature on enzymes. The model describes the effect of temperature on enzyme activity in terms of a rapidly reversible active-inactive transition, in addition to an irreversible thermal inactivation. Two new thermal parameters, T eq and ΔH eq, describe the active–inactive transition, and enable a complete description of the effect of temperature on enzyme activity. We review here the Model itself, methods for the determination of T eq and ΔH eq, and the implications of the Model for the environmental adaptation and evolution of enzymes, and for biotechnology.

text: Review: The effect of temperature on enzyme activity: new insights and their implications The two established thermal properties of enzymes are their activation energy and their thermal stability. Arising from careful measurements of the thermal behaviour of enzymes, a new model, the Equilibrium Model, has been developed to explain more fully the effects of temperature on enzymes. The model describes the effect of temperature on enzyme activity in terms of a rapidly reversible active-inactive transition, in addition to an irreversible thermal inactivation. Two new thermal parameters, T eq and ΔH eq, describe the active–inactive transition, and enable a complete description of the effect of temperature on enzyme activity. We review here the Model itself, methods for the determination of T eq and ΔH eq, and the implications of the Model for the environmental adaptation and evolution of enzymes, and for biotechnology.

year: 2007

title: Robust regression for highly corrupted response by shifting outliers

authors: Jung, Yoonsuh

abstract: Outlying observations are often disregarded at the sacrifice of degrees of freedom or downsized via robust loss functions (e.g., Huber's loss) to reduce the undesirable impact on data analysis. In this article, we treat the outlying status of each observation as a parameter and propose a penalization method to automatically adjust the outliers. The proposed method shifts the outliers towards the fitted values, while preserve the non-outlying observations. We also develop a generally applicable algorithm in the iterative fashion to estimate model parameters and demonstrate the connection with the maximum likelihood based estimation procedure in the case of least squares estimation. We establish asymptotic property of the resulting parameter estimators under the condition that the proportion of outliers does not vanish as sample size increases. We apply the proposed outlier adjustment method to ordinary least squares and lasso-type penalization procedure and demonstrate its empirical value via numeric studies. Furthermore, we study applicability of the proposed method to two robust estimators, Huber's robust estimator and Huberized lasso, and demonstrate its noticeable improvement of model fit in the presence of extremely large outliers.

text: Robust regression for highly corrupted response by shifting outliers Outlying observations are often disregarded at the sacrifice of degrees of freedom or downsized via robust loss functions (e.g., Huber's loss) to reduce the undesirable impact on data analysis. In this article, we treat the outlying status of each observation as a parameter and propose a penalization method to automatically adjust the outliers. The proposed method shifts the outliers towards the fitted values, while preserve the non-outlying observations. We also develop a generally applicable algorithm in the iterative fashion to estimate model parameters and demonstrate the connection with the maximum likelihood based estimation procedure in the case of least squares estimation. We establish asymptotic property of the resulting parameter estimators under the condition that the proportion of outliers does not vanish as sample size increases. We apply the proposed outlier adjustment method to ordinary least squares and lasso-type penalization procedure and demonstrate its empirical value via numeric studies. Furthermore, we study applicability of the proposed method to two robust estimators, Huber's robust estimator and Huberized lasso, and demonstrate its noticeable improvement of model fit in the presence of extremely large outliers.

year: 2016-01-22

title: Sylvia’s place: Ashton-Warner as New Zealand educational theorist.

authors: Middleton, Sue

subjects: educational theorist

abstract: Sylvia Ashton-Warner’s New Zealand educational context has been – and continues to be – misrepresented as antithetical to her creative methods. Sue Middleton, a professor of education, locates Sylvia’s educational ideas within the national and international Progressive Education movement, indicating that key education officials in post-war New Zealand encouraged creativity and self-expression.

This chapter makes the case that, as a teacher, an educational writer and theorist, Sylvia Ashton-Warner grew in, and not in spite of New Zealand. My argument unfolds in two parts. The first reviews theoretical ideas in the local and international educational environment in which Sylvia lived and worked. Sylvia and Keith Henderson taught in what was referred to until 1946 as the Native School system (and from 1948 until its abolition in 1968 as the Maori Scholl system). They trained and began work as teachers during the Great Depression; and Sylvia began serious writing during World War Two. The war and the Native Scholl system interested in complex ways with the wider international Progressive Education movement and its promotion ‘from the top’ in New Zealand’s public schools. An overview of Progressive (or New ) Education, the changing theories of culture and race in the Native School system, and relations between these during World War Two, opens a wide-angled aperture through which to read Sylvia’s early writing.

text: Sylvia’s place: Ashton-Warner as New Zealand educational theorist. Sylvia Ashton-Warner’s New Zealand educational context has been – and continues to be – misrepresented as antithetical to her creative methods. Sue Middleton, a professor of education, locates Sylvia’s educational ideas within the national and international Progressive Education movement, indicating that key education officials in post-war New Zealand encouraged creativity and self-expression.

This chapter makes the case that, as a teacher, an educational writer and theorist, Sylvia Ashton-Warner grew in, and not in spite of New Zealand. My argument unfolds in two parts. The first reviews theoretical ideas in the local and international educational environment in which Sylvia lived and worked. Sylvia and Keith Henderson taught in what was referred to until 1946 as the Native School system (and from 1948 until its abolition in 1968 as the Maori Scholl system). They trained and began work as teachers during the Great Depression; and Sylvia began serious writing during World War Two. The war and the Native Scholl system interested in complex ways with the wider international Progressive Education movement and its promotion ‘from the top’ in New Zealand’s public schools. An overview of Progressive (or New ) Education, the changing theories of culture and race in the Native School system, and relations between these during World War Two, opens a wide-angled aperture through which to read Sylvia’s early writing.

year: 2009