title: Anisotropic viscous dissipation in compressible magnetic X-points

authors: Craig, Ian J.D.

subjects: magnetohydrodynamics

abstract: Context:  Visco-resistive damping in line-tied magnetic X-points is examined.
Aims:  The goal is to determine whether fast, Alfvénic energy dissipation is possible for X-point disturbances damped by the plasma resistivity and non-isotropic viscosity.
Methods:  The response of X-points to planar and axial perturbations is explored numerically by solving the linearized compressible MHD equations in two and a half dimensions.
Results:  It is demonstrated that fast dissipation is possible in the case of non-reconnective planar disturbances damped by anisotropic viscosity in weakly resistive plasmas. Although perturbations which change the initial X-point topology decay slowly at large times when viscous effects are dominant, there is an initial phase in which a significant fraction of the disturbance energy is removed on an Alfvénic timescale. The decay of incompressive axial field disturbances occurs by a different mechanism, however, that is always formally slow (i.e. dependent on the small viscous and resistive damping coefficients).
Conclusions:  Computations suggest that fast, visco-resistive energy release in coronal plasmas is possible for compressive X-point disturbances. This result could have important implications for understanding rapid energy release in coronal active regions.

text: Anisotropic viscous dissipation in compressible magnetic X-points Context:  Visco-resistive damping in line-tied magnetic X-points is examined.
Aims:  The goal is to determine whether fast, Alfvénic energy dissipation is possible for X-point disturbances damped by the plasma resistivity and non-isotropic viscosity.
Methods:  The response of X-points to planar and axial perturbations is explored numerically by solving the linearized compressible MHD equations in two and a half dimensions.
Results:  It is demonstrated that fast dissipation is possible in the case of non-reconnective planar disturbances damped by anisotropic viscosity in weakly resistive plasmas. Although perturbations which change the initial X-point topology decay slowly at large times when viscous effects are dominant, there is an initial phase in which a significant fraction of the disturbance energy is removed on an Alfvénic timescale. The decay of incompressive axial field disturbances occurs by a different mechanism, however, that is always formally slow (i.e. dependent on the small viscous and resistive damping coefficients).
Conclusions:  Computations suggest that fast, visco-resistive energy release in coronal plasmas is possible for compressive X-point disturbances. This result could have important implications for understanding rapid energy release in coronal active regions.

year: 2008

title: Digital management and retrieval of physical documents

authors: Jervis, Matthew Geoffrey

subjects: computer science

abstract: Although in today's everyday work environments digital and paper documents co-exist, the systems used to manage them are often completely separate; digital documents are managed using computer systems, while paper documents are organised and managed using manual systems. Since it is unlikely that the widespread use of paper documents will cease to exist in the foreseeable future, digital systems are needed for managing the storage and retrieval of paper documents which better integrate with existing systems for management of digital documents. This paper presents an architecture for a system to digitally manage paper document containers, such as folders, which has been used as the design basis for a prototype system we have developed. This prototype system aims to resolve some of the problems associated with an earlier prototype we have developed to integrate filing of physical folders with digital document management systems.

text: Digital management and retrieval of physical documents Although in today's everyday work environments digital and paper documents co-exist, the systems used to manage them are often completely separate; digital documents are managed using computer systems, while paper documents are organised and managed using manual systems. Since it is unlikely that the widespread use of paper documents will cease to exist in the foreseeable future, digital systems are needed for managing the storage and retrieval of paper documents which better integrate with existing systems for management of digital documents. This paper presents an architecture for a system to digitally manage paper document containers, such as folders, which has been used as the design basis for a prototype system we have developed. This prototype system aims to resolve some of the problems associated with an earlier prototype we have developed to integrate filing of physical folders with digital document management systems.

year: 2009

title: Kōura in the Rotorua Te Arawa Lakes and potential effects of catfish

authors: Kusabs, Ian

abstract: I am going to talk about kōura and the novel sampling method we are using, then talk about the population characteristics of kōura in the Rotorua Te Arawa Lakes, including results from my PhD research, the Lake Taupō experience with catfish, which Michel Dedual has more than adequately described, and also future work.

text: Kōura in the Rotorua Te Arawa Lakes and potential effects of catfish I am going to talk about kōura and the novel sampling method we are using, then talk about the population characteristics of kōura in the Rotorua Te Arawa Lakes, including results from my PhD research, the Lake Taupō experience with catfish, which Michel Dedual has more than adequately described, and also future work.

year: 2017