title: Analytic solutions of the magnetic annihilation and reconnection problems. I. Planar flow profiles

authors: Watson, P.G.

subjects: mathematics

abstract: The phenomena of steady-state magnetic annihilation and reconnection in the vicinity of magnetic nulls are considered. It is shown that reconnective solutions can be derived by superposing the velocity and magnetic fields of simple magnetic annihilation models. These solutions contain most of the previous models for magnetic merging and reconnection, as well as introducing several new solutions. The various magnetic dissipation mechanisms are classified by examining the scaling of the Ohmic diffusion rate with plasma resistivity. Reconnection solutions generally allow more favorable "fast" dissipation scalings than annihilation models. In particular, reconnection models involving the advection of planar field components have the potential to satisfy the severe energy release requirements of the solar flare. The present paper is mainly concerned with magnetic fields embedded in strictly planar flows—a discussion of the more complicated three-dimensional flow patterns is presented in Part II [Phys. Plasmas 4, 110 (1997)].

text: Analytic solutions of the magnetic annihilation and reconnection problems. I. Planar flow profiles The phenomena of steady-state magnetic annihilation and reconnection in the vicinity of magnetic nulls are considered. It is shown that reconnective solutions can be derived by superposing the velocity and magnetic fields of simple magnetic annihilation models. These solutions contain most of the previous models for magnetic merging and reconnection, as well as introducing several new solutions. The various magnetic dissipation mechanisms are classified by examining the scaling of the Ohmic diffusion rate with plasma resistivity. Reconnection solutions generally allow more favorable "fast" dissipation scalings than annihilation models. In particular, reconnection models involving the advection of planar field components have the potential to satisfy the severe energy release requirements of the solar flare. The present paper is mainly concerned with magnetic fields embedded in strictly planar flows—a discussion of the more complicated three-dimensional flow patterns is presented in Part II [Phys. Plasmas 4, 110 (1997)].

year: 1997-01

title: Neutron frequency windows and the protein dynamical transition

authors: Becker, Torsten

abstract: Proteins undergo an apparent dynamical transition on temperature variation that has been correlated with the onset of function. The transition in the mean-square displacement, ∆r2 , that is observed using a spectrometer or computer simulation, depends on the relationship between the timescales of the relaxation processes activated and the timescale accessible to the instrument or simulation. Models are described of two extreme situations—an "equilibrium" model, in which the long-time dynamics changes with temperature and all motions are resolved by the instrument used; and a "frequency window" model, in which there is no change in the long-time dynamics but as the temperature increases, the relaxation frequencies move into the instrumental range. Here we demonstrate that the latter, frequency-window model can describe the temperature and timescale dependences of both the intermediate neutron scattering function and  ∆r2  derived from molecular dynamics simulations of a small protein in a cryosolution. The frequency-window model also describes the energy-resolution and temperature-dependences of  ∆r2  obtained from experimental neutron scattering on glutamate dehydrogenase in the same solvent. Although equilibrium effects should also contribute to dynamical transitions in proteins, the present results suggests that frequency-window effects can play a role in the simulations and experiments examined. Finally, misquotations of previous findings are discussed in the context of solvent activation of protein dynamics and the possible relationship of this to activity.

text: Neutron frequency windows and the protein dynamical transition Proteins undergo an apparent dynamical transition on temperature variation that has been correlated with the onset of function. The transition in the mean-square displacement, ∆r2 , that is observed using a spectrometer or computer simulation, depends on the relationship between the timescales of the relaxation processes activated and the timescale accessible to the instrument or simulation. Models are described of two extreme situations—an "equilibrium" model, in which the long-time dynamics changes with temperature and all motions are resolved by the instrument used; and a "frequency window" model, in which there is no change in the long-time dynamics but as the temperature increases, the relaxation frequencies move into the instrumental range. Here we demonstrate that the latter, frequency-window model can describe the temperature and timescale dependences of both the intermediate neutron scattering function and  ∆r2  derived from molecular dynamics simulations of a small protein in a cryosolution. The frequency-window model also describes the energy-resolution and temperature-dependences of  ∆r2  obtained from experimental neutron scattering on glutamate dehydrogenase in the same solvent. Although equilibrium effects should also contribute to dynamical transitions in proteins, the present results suggests that frequency-window effects can play a role in the simulations and experiments examined. Finally, misquotations of previous findings are discussed in the context of solvent activation of protein dynamics and the possible relationship of this to activity.

year: 2004-09

title: Arts Festival: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary'

authors: Perrott, Lisa

subjects: Art

abstract: Research presentation - an audiovisual presentation drawing upon my published research (book chapter: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary'). This presentation presented a Matuaranga Maori perspective of the temporal travels of music video and documentary, framed by the concept of whakapap. This presentation took place as part of a panel of 4 presenters who represented Te Kura Toi at the Arts Festival during the University of Waikato Open Day, 2023. This was an oral presentation, which included projected slides and videos from a PPT presentation. The audience included prospective students, their teachers and family members, community members, and current students and academic staff from the University of Waikato. My presentation was documented and photographed.

text: Arts Festival: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary' Research presentation - an audiovisual presentation drawing upon my published research (book chapter: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary'). This presentation presented a Matuaranga Maori perspective of the temporal travels of music video and documentary, framed by the concept of whakapap. This presentation took place as part of a panel of 4 presenters who represented Te Kura Toi at the Arts Festival during the University of Waikato Open Day, 2023. This was an oral presentation, which included projected slides and videos from a PPT presentation. The audience included prospective students, their teachers and family members, community members, and current students and academic staff from the University of Waikato. My presentation was documented and photographed.

year: 2023-05-26