title: Toward a reconnection model for solar flare statistics

authors: Wheatland, M.S.

subjects: MHD—sun

abstract: A model to account for observed solar flare statistics in terms of a superposition of independent random flaring elements (assumed to be sites of magnetic reconnection in the coronal magnetic field and hence termed “separators”) is described. A separator of length  is assumed to flare as a Poisson process in time, with a rate v(l) inversely proportional to the Alfvén transit time for the structure. It is shown that a relationship ξ∞lk between the mean energy of events ξ at a separator and the separator length implies a relationship E∞Tk between individual waiting times τ and energies E of events at the separator. The most plausible K=2 model is found to be compatible with simple pictures for magnetohydrodynamic energy storage prior to magnetic reconnection in a current sheet with anomalous (turbulent) resistivity. Formal inversion of the observed flare frequency-energy distribution is shown to imply a distribution P(l) ∞l-1 of the separator lengths in active regions. A simulation confirms the basic results of the model. It is also demonstrated that a model comprising time-dependent separator numbers N=N(t) can reproduce an observed power-law tail in the flare waiting-time distribution, for large waiting times.

text: Toward a reconnection model for solar flare statistics A model to account for observed solar flare statistics in terms of a superposition of independent random flaring elements (assumed to be sites of magnetic reconnection in the coronal magnetic field and hence termed “separators”) is described. A separator of length  is assumed to flare as a Poisson process in time, with a rate v(l) inversely proportional to the Alfvén transit time for the structure. It is shown that a relationship ξ∞lk between the mean energy of events ξ at a separator and the separator length implies a relationship E∞Tk between individual waiting times τ and energies E of events at the separator. The most plausible K=2 model is found to be compatible with simple pictures for magnetohydrodynamic energy storage prior to magnetic reconnection in a current sheet with anomalous (turbulent) resistivity. Formal inversion of the observed flare frequency-energy distribution is shown to imply a distribution P(l) ∞l-1 of the separator lengths in active regions. A simulation confirms the basic results of the model. It is also demonstrated that a model comprising time-dependent separator numbers N=N(t) can reproduce an observed power-law tail in the flare waiting-time distribution, for large waiting times.

year: 2003-09

title: Drying curves and apparent diffusivity of New Zealand chestnut variety ‘1015’

authors: Biju Cletus, Anila

subjects: chestnuts

abstract: New Zealand chestnuts grow relatively large by comparison with Asian or American varieties and have the potential to be a lucrative crop. However they are susceptible to fungal rots and need to be dried at relatively low temperatures in order to prevent significant spoilage. Drying curves for New Zealand chestnut variety ‘1015’ were obtained at 30 °C, which was the maximum drying temperature that did not cause significant quality degradation. Two distinct falling-rate drying periods were observed: an initial period during which a relatively high drying rate decreased rapidly, followed by a period of lower drying rates which decreased only gradually. The first period most likely corresponded to the time required for the surface region to reach moisture equilibrium, since it was clearly affected by external factors such as air movement and the absence or presence of moisture barrier(s). The second period represented the diffusion-controlled process, and was largely unaffected by external factors. The mean apparent diffusivity of whole chestnuts at 30 °C was 5.1 × 10⁻¹¹ m² s⁻¹.

text: Drying curves and apparent diffusivity of New Zealand chestnut variety ‘1015’ New Zealand chestnuts grow relatively large by comparison with Asian or American varieties and have the potential to be a lucrative crop. However they are susceptible to fungal rots and need to be dried at relatively low temperatures in order to prevent significant spoilage. Drying curves for New Zealand chestnut variety ‘1015’ were obtained at 30 °C, which was the maximum drying temperature that did not cause significant quality degradation. Two distinct falling-rate drying periods were observed: an initial period during which a relatively high drying rate decreased rapidly, followed by a period of lower drying rates which decreased only gradually. The first period most likely corresponded to the time required for the surface region to reach moisture equilibrium, since it was clearly affected by external factors such as air movement and the absence or presence of moisture barrier(s). The second period represented the diffusion-controlled process, and was largely unaffected by external factors. The mean apparent diffusivity of whole chestnuts at 30 °C was 5.1 × 10⁻¹¹ m² s⁻¹.

year: 2008

title: Photography within te ao Māori: Decolonising the photographic lens

authors: Hill, Rodrigo

abstract: Ūkaipō: Wānanga, places of origin and photographic representation. 
Ūkaipō recognises the cultural, emotional, and spiritual along with the physical ties a Māori has with their place of origin, even if it is not their place of birth, emphasising grounded forms of connection between people and place and subsequent understandings of places and spaces.  Hence the importance today of people asserting their pēpeha, tohu whenua landmarks with which they most strongly identify, consolidating their ‘birth of place’ or ‘place of birth’.

text: Photography within te ao Māori: Decolonising the photographic lens Ūkaipō: Wānanga, places of origin and photographic representation. 
Ūkaipō recognises the cultural, emotional, and spiritual along with the physical ties a Māori has with their place of origin, even if it is not their place of birth, emphasising grounded forms of connection between people and place and subsequent understandings of places and spaces.  Hence the importance today of people asserting their pēpeha, tohu whenua landmarks with which they most strongly identify, consolidating their ‘birth of place’ or ‘place of birth’.

year: 2024