title: Hall current effects in dynamic magnetic reconnection solutions

authors: Craig, Ian J.D.

subjects: mathematics

abstract: The impact of Hall current contributions on flow driven planar magnetic merging solutions is discussed. The Hall current is important if the dimensionless Hall parameter (or normalized ion skin depth) satisfies cH>η where η is the inverse Lundquist number for the plasma. A dynamic analysis of the problem shows, however, that the Hall current initially manifests itself, not by modifying the planar reconnection field, but by inducing a non-reconnecting perpendicular "separator" component in the magnetic field. Only if the stronger condition c2/H > η is satisfied can Hall currents be expected to affect the planar merging. These analytic predictions are then tested by performing a series of numerical experiments in periodic geometry, using the full system of planar magnetohydrodynamic (MHD) equations. The numerical results confirm that the nature of the merging changes dramatically when the Hall coupling satisfies c2/H > η. In line with the analytic treatment of sheared reconnection, the coupling provided by the Hall term leads to the emergence of multiple current layers that can enhance the global Ohmic dissipation at the expense of the reconnection rate. However, the details of the dissipation depend critically on the symmetries of the simulation, and when the merging is "head-on" (i.e., comprises fourfold symmetry) the reconnection rate can be enhanced.

text: Hall current effects in dynamic magnetic reconnection solutions The impact of Hall current contributions on flow driven planar magnetic merging solutions is discussed. The Hall current is important if the dimensionless Hall parameter (or normalized ion skin depth) satisfies cH>η where η is the inverse Lundquist number for the plasma. A dynamic analysis of the problem shows, however, that the Hall current initially manifests itself, not by modifying the planar reconnection field, but by inducing a non-reconnecting perpendicular "separator" component in the magnetic field. Only if the stronger condition c2/H > η is satisfied can Hall currents be expected to affect the planar merging. These analytic predictions are then tested by performing a series of numerical experiments in periodic geometry, using the full system of planar magnetohydrodynamic (MHD) equations. The numerical results confirm that the nature of the merging changes dramatically when the Hall coupling satisfies c2/H > η. In line with the analytic treatment of sheared reconnection, the coupling provided by the Hall term leads to the emergence of multiple current layers that can enhance the global Ohmic dissipation at the expense of the reconnection rate. However, the details of the dissipation depend critically on the symmetries of the simulation, and when the merging is "head-on" (i.e., comprises fourfold symmetry) the reconnection rate can be enhanced.

year: 2003-04-16

title: The efficacy of systematic desensitization for treating the separation-related problem behaviour of domestic dogs

authors: Butler, Rynae

subjects: systematic desensitization

abstract: The evaluation of systematic desensitization to treat separation-related problem behaviours, such as destruction of property, excessive barking, or house-soiling, has tended to rely on single case-studies. Eight dogs exhibiting separation-related behaviour, and their owners, participated in a controlled experiment using a within-subjects design to evaluate the efficacy of a combination of systematic desensitization and counter-conditioning. Treatment produced significant reductions in both the frequency (T(9)) = 0.0, P = 0.008) and the severity (T(9)) = 0.0, P = 0.008) of separation-related behaviours compared to baseline. Six dogs, for which follow-up data were obtained three months after treatment ended, showed almost complete elimination of the problem behaviour. The use of counter-conditioning, and other behavioural advice, did not appear to be related to the success of the treatment, suggesting that systematic desensitization was the critical element. Speed of progress and final success was not related to the consistency with which the owners applied systematic desensitization, indicating that even when owners apply systematic desensitization haphazardly, it can still be successful in treating separation-related behaviour in dogs.

text: The efficacy of systematic desensitization for treating the separation-related problem behaviour of domestic dogs The evaluation of systematic desensitization to treat separation-related problem behaviours, such as destruction of property, excessive barking, or house-soiling, has tended to rely on single case-studies. Eight dogs exhibiting separation-related behaviour, and their owners, participated in a controlled experiment using a within-subjects design to evaluate the efficacy of a combination of systematic desensitization and counter-conditioning. Treatment produced significant reductions in both the frequency (T(9)) = 0.0, P = 0.008) and the severity (T(9)) = 0.0, P = 0.008) of separation-related behaviours compared to baseline. Six dogs, for which follow-up data were obtained three months after treatment ended, showed almost complete elimination of the problem behaviour. The use of counter-conditioning, and other behavioural advice, did not appear to be related to the success of the treatment, suggesting that systematic desensitization was the critical element. Speed of progress and final success was not related to the consistency with which the owners applied systematic desensitization, indicating that even when owners apply systematic desensitization haphazardly, it can still be successful in treating separation-related behaviour in dogs.

year: 2010

title: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism

authors: Marsh, Tuihana M.

subjects: Partner Terrorism

abstract: Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

text: Violation of te whare tangata - the maternal body: Young women's journeys through pregnancy and partner terrorism Partner terrorism is a leading social issue in Aotearoa. It occurs with such frequency and ferocity that it is often considered an epidemic. This has placed us in the shameful position of being the highest ranked nation in the western world for the prevalence of intimate partner violence. This research explored young women’s experiences of intimate partner violence during pregnancy. Eleven women aged 14 - 17 years when pregnant were interviewed. A mana wāhine theoretical perspective was employed, guided by a kaupapa Māori research methodology. Pūrākau was used as a method to present and validate the women’s voices.
The key findings identified that these relationships began with the potential of any other relationship. However, they typically followed a pattern of co-habituation and entrapment through pregnancy and financial dependence. It was evident the partner terrorism was brought into these relationships by the terrorist partners, and was the first experience of this violence for many of the women. The terrorism continued to escalate. Separating from their terrorist partners did not result in the women being any safer, with some continuing to experience life-threatening acts of terrorism post separation. Pregnancy did not serve as a protective factor: the violation of te whare tangata generally occurred before, during and after pregnancy. Often, the acts of terrorism escalated following the birth of their pēpī, with their partner’s terrorism being a direct assault on ūkaipō, disrupting bonding and mothering practices. Many of the women were able to recognise the terrorism to which they were subjected only in hindsight. Despite this, they showed ingenuity and resilience in the ways they resisted the terrorism in efforts to keep themselves and their pēpī safe. Breaking free of these relationships demanded intervention and support from outsiders. The women remain strongly committed to the welfare of their pēpī.

year: 2019