title: Kinetic helicity and MHD turbulence

authors: Oughton, Sean

subjects: MHD turbulence

abstract: The issue of dynamical anisotropy in helical three-dimensional magnetohydrodynamic turbulence with a mean magnetic field B₀ is investigated. Using high-resolution direct numerical simulations, we follow the evolution of various isotropic initial states characterized by their different values of the kinetic helicity. The cross helicity and magnetic helicity of the initial conditions are also varied. In agreement with earlier work, we find that such initial states become anisotropic in of order an eddy-turnover time, with correlation lengths parallel to B₀ remaining largely unchanged while finer scales are excited in the perpendicular directions. Moreover, it is found that the development of both the anisotropy and the energy are essentially independent of the initial level of kinetic helicity. The physics associated with this latter feature is discussed.

text: Kinetic helicity and MHD turbulence The issue of dynamical anisotropy in helical three-dimensional magnetohydrodynamic turbulence with a mean magnetic field B₀ is investigated. Using high-resolution direct numerical simulations, we follow the evolution of various isotropic initial states characterized by their different values of the kinetic helicity. The cross helicity and magnetic helicity of the initial conditions are also varied. In agreement with earlier work, we find that such initial states become anisotropic in of order an eddy-turnover time, with correlation lengths parallel to B₀ remaining largely unchanged while finer scales are excited in the perpendicular directions. Moreover, it is found that the development of both the anisotropy and the energy are essentially independent of the initial level of kinetic helicity. The physics associated with this latter feature is discussed.

year: 2000

title: Applying generalisability theory to differentiate between trait and state in the Five Facet Mindfulness Questionnaire (FFMQ)

authors: Truong, Quoc Cuong

subjects: mindfulness

abstract: Mindfulness has been applied as an effective therapy in clinical settings to treat psychological symptoms (e.g., depression, stress, anxiety) and also in many other contexts (e.g., the workplace, educational contexts, and sports). Accurate evaluation of mindfulness-based training or mindfulness research requires distinguishing between state and trait changes. The failure to distinguish trait from state in a mindfulness measurement may confuse the assessment results of neurophysiological and psychological mindfulness studies, as well as mindfulness-based treatments, because mindfulness can be understood as either a state or a trait. The Five Facet Mindfulness Questionnaire (FFMQ) is the most widely used multidimentional assessment tool of dispositional mindfulness, comprised of five subscales: “act with awareness”, “describe”, “nonjudge”, “nonreact”, and “observe”. Its short version, consisting of 18 items (FFMQ-18), was proposed by examining and comparing the existing short versions of the FFMQ. However, the ability of the FFMQ to accurately capture stable aspects of mindfulness has not been studied thoroughly, using robust methodology. The generalisability theory (G-theory) is the most suitable and robust statistical approach to differentiate and measure these aspects.
In this study, G-theory was applied to distinguish between dynamic (state) and enduring (trait) aspects of mindfulness and to evaluate the reliability of the FFMQ and the FFMQ-18 over time. The study used data from 83 participants, who completed the test on three occasions separated by 2-week intervals. The full 39-item FFMQ and the shorter FFMQ-18 version proved to be very reliable in measuring trait mindfulness, with G coefficients of 0.89 and 0.75, respectively, while individual facet subscales of the FFMQ appeared to be less reliable in measuring trait mindfulness. Subsequent analyses attempted to combine the FFMQ items that were least stable over time to form a measure of state mindfulness. However, these did not result in acceptable psychometric properties for such a state subscale. The findings of this study indicate that a reliable assessment of stable aspects of mindfulness can be achieved by using the full FFMQ scale or its short FFMQ-18 version, with scores that can be generalised across the sample population and assessment occasions. The scores obtained on individual facet subscales of the FFMQ predominantly measure trait mindfulness but their reliability is affected by measurement error, resulting from interaction between persons, items and occasions.

text: Applying generalisability theory to differentiate between trait and state in the Five Facet Mindfulness Questionnaire (FFMQ) Mindfulness has been applied as an effective therapy in clinical settings to treat psychological symptoms (e.g., depression, stress, anxiety) and also in many other contexts (e.g., the workplace, educational contexts, and sports). Accurate evaluation of mindfulness-based training or mindfulness research requires distinguishing between state and trait changes. The failure to distinguish trait from state in a mindfulness measurement may confuse the assessment results of neurophysiological and psychological mindfulness studies, as well as mindfulness-based treatments, because mindfulness can be understood as either a state or a trait. The Five Facet Mindfulness Questionnaire (FFMQ) is the most widely used multidimentional assessment tool of dispositional mindfulness, comprised of five subscales: “act with awareness”, “describe”, “nonjudge”, “nonreact”, and “observe”. Its short version, consisting of 18 items (FFMQ-18), was proposed by examining and comparing the existing short versions of the FFMQ. However, the ability of the FFMQ to accurately capture stable aspects of mindfulness has not been studied thoroughly, using robust methodology. The generalisability theory (G-theory) is the most suitable and robust statistical approach to differentiate and measure these aspects.
In this study, G-theory was applied to distinguish between dynamic (state) and enduring (trait) aspects of mindfulness and to evaluate the reliability of the FFMQ and the FFMQ-18 over time. The study used data from 83 participants, who completed the test on three occasions separated by 2-week intervals. The full 39-item FFMQ and the shorter FFMQ-18 version proved to be very reliable in measuring trait mindfulness, with G coefficients of 0.89 and 0.75, respectively, while individual facet subscales of the FFMQ appeared to be less reliable in measuring trait mindfulness. Subsequent analyses attempted to combine the FFMQ items that were least stable over time to form a measure of state mindfulness. However, these did not result in acceptable psychometric properties for such a state subscale. The findings of this study indicate that a reliable assessment of stable aspects of mindfulness can be achieved by using the full FFMQ scale or its short FFMQ-18 version, with scores that can be generalised across the sample population and assessment occasions. The scores obtained on individual facet subscales of the FFMQ predominantly measure trait mindfulness but their reliability is affected by measurement error, resulting from interaction between persons, items and occasions.

year: 2020

title: Surplus Public Works Land: The Crown's Special Duty to Maori

authors: Grayson, Michael Robert

subjects: Maori

abstract: The Crown's obligations to Maori regarding the offer back of surplus Crown land under s40 of the Public Works Act 1981.

text: Surplus Public Works Land: The Crown's Special Duty to Maori The Crown's obligations to Maori regarding the offer back of surplus Crown land under s40 of the Public Works Act 1981.

year: 2017