title: Direct comparisons of compressible magnetohydrodynamics and reduced magnetohydrodynamics turbulence

authors: Oughton, Sean

subjects: mathematics

abstract: Direct numerical simulations of low Mach number compressible three-dimensional magnetohydrodynamic (CMHD3D) turbulence in the presence of a strong mean magnetic field are compared with simulations of reduced magnetohydrodynamics (RMHD). Periodic boundary conditions in the three spatial coordinates are considered. Different sets of initial conditions are chosen to explore the applicability of RMHD and to study how close the solution remains to the full compressible MHD solution as both freely evolve in time. In a first set, the initial state is prepared to satisfy the conditions assumed in the derivation of RMHD, namely, a strong mean magnetic field and plane-polarized fluctuations, varying weakly along the mean magnetic field. In those circumstances, simulations show that RMHD and CMHD3D evolve almost indistinguishably from one another. When some of the conditions are relaxed the agreement worsens but RMHD remains fairly close to CMHD3D, especially when the mean magnetic field is large enough. Moreover, the well-known spectral anisotropy effect promotes the dynamical attainment of the conditions for RMHD applicability. Global quantities (mean energies, mean-square current, and vorticity) and energy spectra from the two solutions are compared and point-to-point separation estimations are computed. The specific results shown here give support to the use of RMHD as a valid approximation of compressible MHD with a mean magnetic field under certain but quite practical conditions.

text: Direct comparisons of compressible magnetohydrodynamics and reduced magnetohydrodynamics turbulence Direct numerical simulations of low Mach number compressible three-dimensional magnetohydrodynamic (CMHD3D) turbulence in the presence of a strong mean magnetic field are compared with simulations of reduced magnetohydrodynamics (RMHD). Periodic boundary conditions in the three spatial coordinates are considered. Different sets of initial conditions are chosen to explore the applicability of RMHD and to study how close the solution remains to the full compressible MHD solution as both freely evolve in time. In a first set, the initial state is prepared to satisfy the conditions assumed in the derivation of RMHD, namely, a strong mean magnetic field and plane-polarized fluctuations, varying weakly along the mean magnetic field. In those circumstances, simulations show that RMHD and CMHD3D evolve almost indistinguishably from one another. When some of the conditions are relaxed the agreement worsens but RMHD remains fairly close to CMHD3D, especially when the mean magnetic field is large enough. Moreover, the well-known spectral anisotropy effect promotes the dynamical attainment of the conditions for RMHD applicability. Global quantities (mean energies, mean-square current, and vorticity) and energy spectra from the two solutions are compared and point-to-point separation estimations are computed. The specific results shown here give support to the use of RMHD as a valid approximation of compressible MHD with a mean magnetic field under certain but quite practical conditions.

year: 2005-11-11

title: Teacher professional identities in ece: Complexities and contradictions

authors: Kamenarac, Olivera

subjects: Teachers professional identities

abstract: By applying a framework of poststructural discursive studies and theoretical ideas of feminist poststructuralists, my doctoral thesis investigates how teachers’ professional identities have been discursively constructed in ECEC policies and practice in Aotearoa New Zealand over the last two decades. The study draws on discourse analysis of influential policy documents and transcript texts from group and individual interviews with teachers, professional leaders and managers from both community-owned and for-profit ECEC services. Research findings illustrate that the Aotearoa New Zealand ECEC has been torn between tensions created through an interplay of divergent and opposing discursive windows, which set a powerful context for constructions of complex, contradictory and fluid teachers’ professional identities. The study argues that discursive windows of enterprise, economic investment and vulnerability have promoted competition, individualism, entrepreneurship and social-intervention emphases in the sector, and frequently overpowered discourses of collectivism, collegiality, and empowerment, in which democratic education, teachers’ activism and professionalism have been rooted. The study advocates for the advocate-activist early childhood profession and teaching professionals who can bring in a much needed paradigm shift in the contemporary context of ECEC. It is hoped that this research contributes to an understanding of discourses that can strengthen capacity for constructing advocate-activist teachers’ identities at times when the market drives teachers’ work, requiring them to favour for-profit and enterprise interests over the wellbeing of children, families and community.

text: Teacher professional identities in ece: Complexities and contradictions By applying a framework of poststructural discursive studies and theoretical ideas of feminist poststructuralists, my doctoral thesis investigates how teachers’ professional identities have been discursively constructed in ECEC policies and practice in Aotearoa New Zealand over the last two decades. The study draws on discourse analysis of influential policy documents and transcript texts from group and individual interviews with teachers, professional leaders and managers from both community-owned and for-profit ECEC services. Research findings illustrate that the Aotearoa New Zealand ECEC has been torn between tensions created through an interplay of divergent and opposing discursive windows, which set a powerful context for constructions of complex, contradictory and fluid teachers’ professional identities. The study argues that discursive windows of enterprise, economic investment and vulnerability have promoted competition, individualism, entrepreneurship and social-intervention emphases in the sector, and frequently overpowered discourses of collectivism, collegiality, and empowerment, in which democratic education, teachers’ activism and professionalism have been rooted. The study advocates for the advocate-activist early childhood profession and teaching professionals who can bring in a much needed paradigm shift in the contemporary context of ECEC. It is hoped that this research contributes to an understanding of discourses that can strengthen capacity for constructing advocate-activist teachers’ identities at times when the market drives teachers’ work, requiring them to favour for-profit and enterprise interests over the wellbeing of children, families and community.

year: 2018

title: Possibilities of transformation: discourses of difference in organisational communication

authors: Jones, Deborah Helen

abstract: In this thesis I set out to create an interdisciplinary location from which to address the relationship between gender and communication in an organisational context. I draw on feminist and post-structuralist theory to ask the question: How is ‘difference’ constructed in organisational communication? I use the term ‘difference’ here to indicate that I am interested in how ‘gender’ works in relationship with other kinds of difference, especially in relation to ethnic difference.

My thesis is intended as a contribution to feminist communication theory, and specifically, to the emerging field of feminist organisational communication. Because of the approach I take to ‘communication’, this project addresses broad issues of identity, agency and discourse in organisations. In this sense, I also see the thesis as a contribution to organisational studies, and particularly to the study of organisational discourse, which opens up new relationships between ‘organisation’ and ‘communication’. Interdisciplinarity itself is a key issue in my thesis, as I set out to create connections between disciplinary fields in the service of contesting them, rather than seeking to create new boundaries. A second key focus is the development of theoretical sophistication in the field of gender and communication. I draw on feminist/post-structuralist theory, especially feminist readings of Michel Foucault’s work to generate this development. My third key focus is the issue of agency, which I see as central to theorising organisational transformation, and also as central to re-thinking communication theory.

My writing strategies demonstrate my commitments to reflexivity in developing feminist/post-structuralist research epistemologies, and I experiment with ways of paying attention to issues of authority throughout the thesis. This thesis is divided into two main parts. In Chapters 2 to 6, I set up a theoretical framework for feminist/post-structuralist accounts of gender and ethnicity, and weave this theory through the literatures of ‘gender and communication’, ‘cross-cultural communication’, and ‘organisational communication’. I set out to produce an ‘autocritique’, an opportunity to draw on developments in post-structuralist theory to think differently about feminist ‘organisational communication’, putting it within a broader framework of ‘difference’.

In the second part of the thesis, Chapters 7 to 12, I put issues generated by this theoretical framework in a specific organisational context, asking: How are gender and ethnic differences constructed in the discourses of Equal Employment Opportunities (EEO) and Biculturalism in New Zealand government organisations? Chapters 7 and 8 introduce my field studies methodology and research subjects, and provide background narratives which frame the historical and cultural context in which they were carried out. In Chapters 9 to 12 I carry out a discourse analysis of interviews with EEO and Biculturalism practitioners, and also analyse published and unpublished documents associated with ‘difference’ in employment policies. These accounts of field studies are intended as a series of experiments with theorising ‘organisational communication’ in different ways. I complete the thesis with a ‘Review’ (Chapter 13) in which I reflect on key theoretical threads, and on further questions that emerged during the project.

text: Possibilities of transformation: discourses of difference in organisational communication In this thesis I set out to create an interdisciplinary location from which to address the relationship between gender and communication in an organisational context. I draw on feminist and post-structuralist theory to ask the question: How is ‘difference’ constructed in organisational communication? I use the term ‘difference’ here to indicate that I am interested in how ‘gender’ works in relationship with other kinds of difference, especially in relation to ethnic difference.

My thesis is intended as a contribution to feminist communication theory, and specifically, to the emerging field of feminist organisational communication. Because of the approach I take to ‘communication’, this project addresses broad issues of identity, agency and discourse in organisations. In this sense, I also see the thesis as a contribution to organisational studies, and particularly to the study of organisational discourse, which opens up new relationships between ‘organisation’ and ‘communication’. Interdisciplinarity itself is a key issue in my thesis, as I set out to create connections between disciplinary fields in the service of contesting them, rather than seeking to create new boundaries. A second key focus is the development of theoretical sophistication in the field of gender and communication. I draw on feminist/post-structuralist theory, especially feminist readings of Michel Foucault’s work to generate this development. My third key focus is the issue of agency, which I see as central to theorising organisational transformation, and also as central to re-thinking communication theory.

My writing strategies demonstrate my commitments to reflexivity in developing feminist/post-structuralist research epistemologies, and I experiment with ways of paying attention to issues of authority throughout the thesis. This thesis is divided into two main parts. In Chapters 2 to 6, I set up a theoretical framework for feminist/post-structuralist accounts of gender and ethnicity, and weave this theory through the literatures of ‘gender and communication’, ‘cross-cultural communication’, and ‘organisational communication’. I set out to produce an ‘autocritique’, an opportunity to draw on developments in post-structuralist theory to think differently about feminist ‘organisational communication’, putting it within a broader framework of ‘difference’.

In the second part of the thesis, Chapters 7 to 12, I put issues generated by this theoretical framework in a specific organisational context, asking: How are gender and ethnic differences constructed in the discourses of Equal Employment Opportunities (EEO) and Biculturalism in New Zealand government organisations? Chapters 7 and 8 introduce my field studies methodology and research subjects, and provide background narratives which frame the historical and cultural context in which they were carried out. In Chapters 9 to 12 I carry out a discourse analysis of interviews with EEO and Biculturalism practitioners, and also analyse published and unpublished documents associated with ‘difference’ in employment policies. These accounts of field studies are intended as a series of experiments with theorising ‘organisational communication’ in different ways. I complete the thesis with a ‘Review’ (Chapter 13) in which I reflect on key theoretical threads, and on further questions that emerged during the project.

year: 1998