title: Nonlinear Effects in Three-minute Oscillations of the Solar Chromosphere. I. An Analytical Nonlinear Solution and Detection of the Second Harmonic

authors: Chae, Jongchul

subjects: hydrodynamics

abstract: The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the short- and long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of interpolating between the two limits. Physical features of the nonlinear waves in the chromosphere are described, including the dispersive nature of low-frequency waves, the steepening of the wave profile, and the influence of the gravitational field on wavefront breaking and shock formation. The analytical results suggest that observations of three-minute oscillations in the solar chromosphere may reveal the basic nonlinear effect of oscillations with combination frequencies, superposed on the normal oscillations of the system. Explicit expressions for a second-harmonic signal and the ratio of its amplitude to the fundamental harmonic amplitude are derived. Observational evidence of the second harmonic, obtained with the Fast Imaging Solar Spectrograph, installed at the 1.6 m New Solar Telescope of the Big Bear Observatory, is presented. The presented data are based on the time variations of velocity determined from the Na i D₂ and Hα lines.

text: Nonlinear Effects in Three-minute Oscillations of the Solar Chromosphere. I. An Analytical Nonlinear Solution and Detection of the Second Harmonic The vertical propagation of nonlinear acoustic waves in an isothermal atmosphere is considered. A new analytical solution that describes a finite-amplitude wave of an arbitrary wavelength is obtained. Although the short- and long-wavelength limits were previously considered separately, the new solution describes both limiting cases within a common framework and provides a straightforward way of interpolating between the two limits. Physical features of the nonlinear waves in the chromosphere are described, including the dispersive nature of low-frequency waves, the steepening of the wave profile, and the influence of the gravitational field on wavefront breaking and shock formation. The analytical results suggest that observations of three-minute oscillations in the solar chromosphere may reveal the basic nonlinear effect of oscillations with combination frequencies, superposed on the normal oscillations of the system. Explicit expressions for a second-harmonic signal and the ratio of its amplitude to the fundamental harmonic amplitude are derived. Observational evidence of the second harmonic, obtained with the Fast Imaging Solar Spectrograph, installed at the 1.6 m New Solar Telescope of the Big Bear Observatory, is presented. The presented data are based on the time variations of velocity determined from the Na i D₂ and Hα lines.

year: 2017

title: Clean and green with deepening shadows? a non-complacent view of corruption in New Zealand

authors: Gregory, Robert

subjects: New Zealand

abstract: New Zealand has long been regarded as a country with little or no governmental corruption. In recent times it has been ranked consistently as one of the five least corrupt countries in the world, on Transparency International’s (TI) Corruption Perceptions Index (CPI). In 2009 and 2011 it was ranked as the single most corruption-free country on the CPI, and in 2012 it shared first place with Denmark and Finland. This paper examines the reasons why historically New Zealand has been largely free of governmental corruption, using widely accepted definitions of what constitutes corrupt behaviour. It goes on to argue that, at least by its own normal standards, the country might now be more susceptible to corruption, for a variety of reasons, in both the public and private sectors, and that more political and administrative attention may need to be paid to this issue. The paper discusses New Zealand’s surprising tardiness in ratifying the United Nations Convention against Corruption, an apparent reluctance that leaves the country sitting alongside other non-ratifying countries which have endemic levels of corruption in all its forms. In this context, the paper also notes some international dissatisfaction with New Zealand’s anti-money laundering legislation, enacted in 2009.

text: Clean and green with deepening shadows? a non-complacent view of corruption in New Zealand New Zealand has long been regarded as a country with little or no governmental corruption. In recent times it has been ranked consistently as one of the five least corrupt countries in the world, on Transparency International’s (TI) Corruption Perceptions Index (CPI). In 2009 and 2011 it was ranked as the single most corruption-free country on the CPI, and in 2012 it shared first place with Denmark and Finland. This paper examines the reasons why historically New Zealand has been largely free of governmental corruption, using widely accepted definitions of what constitutes corrupt behaviour. It goes on to argue that, at least by its own normal standards, the country might now be more susceptible to corruption, for a variety of reasons, in both the public and private sectors, and that more political and administrative attention may need to be paid to this issue. The paper discusses New Zealand’s surprising tardiness in ratifying the United Nations Convention against Corruption, an apparent reluctance that leaves the country sitting alongside other non-ratifying countries which have endemic levels of corruption in all its forms. In this context, the paper also notes some international dissatisfaction with New Zealand’s anti-money laundering legislation, enacted in 2009.

year: 2013

title: ‘Hospitality’, boundary crossing and thresholds applied in education: Embodying manaakitanga and whanaungatanga

authors: Wright, Noeline

abstract: In everyday understanding, ‘hospitality’ refers to paid work contexts; commodities and transactional tasks. Hospitality can, however, have much broader significance. It can be understood in cultural and social terms within and beyond transactional contexts. In Māori cultural knowledge and practices for example, hospitality has reciprocal, relational nuances. Perhaps both views imply that ‘hospitality’ is an act of ‘crossing boundaries […] or thresholds’ as Still (2013: 4) suggested. Relational, reciprocal, boundary-crossing practices may also infer ritual understandings of respect, kindness, generosity and harmony. Crossing thresholds is a central concept in Māori knowledge and practices and is central to this article exploring concepts and practices of hospitality in a new primary school focused on building its practices on relational and reciprocal values. In Aotearoa New Zealand educational contexts, hospitality is a cultural, social reciprocal and relational practice. Thus, through examining ‘hospitality’, ‘borders’ and ‘thresholds’ across the boundaries of education and commerce, we hope to illuminate both connections and differences. We do so through reviewing both literature about ‘hospitality’, ‘borders’ and ‘thresholds’ and interview data from a new school intentionally valuing whanaungatanga.

text: ‘Hospitality’, boundary crossing and thresholds applied in education: Embodying manaakitanga and whanaungatanga In everyday understanding, ‘hospitality’ refers to paid work contexts; commodities and transactional tasks. Hospitality can, however, have much broader significance. It can be understood in cultural and social terms within and beyond transactional contexts. In Māori cultural knowledge and practices for example, hospitality has reciprocal, relational nuances. Perhaps both views imply that ‘hospitality’ is an act of ‘crossing boundaries […] or thresholds’ as Still (2013: 4) suggested. Relational, reciprocal, boundary-crossing practices may also infer ritual understandings of respect, kindness, generosity and harmony. Crossing thresholds is a central concept in Māori knowledge and practices and is central to this article exploring concepts and practices of hospitality in a new primary school focused on building its practices on relational and reciprocal values. In Aotearoa New Zealand educational contexts, hospitality is a cultural, social reciprocal and relational practice. Thus, through examining ‘hospitality’, ‘borders’ and ‘thresholds’ across the boundaries of education and commerce, we hope to illuminate both connections and differences. We do so through reviewing both literature about ‘hospitality’, ‘borders’ and ‘thresholds’ and interview data from a new school intentionally valuing whanaungatanga.

year: 2021-03-01