title: The sleep cycle modelled as a cortical phase transition

authors: Steyn-Ross, D. Alistair

subjects: cortical model

abstract: We present a mean-field model of the cortex that attempts to describe the gross changes in brain electrical activity for the cycles of natural sleep. We incorporate within the model two major sleep modulatory effects: slow changes in both synaptic efficiency and in neuron resting voltage caused by the ∼90-min cycling in acetylcholine, together with even slower changes in resting voltage caused by gradual elimination during sleep of somnogens (fatigue agents) such as adenosine. We argue that the change from slow-wave sleep (SWS) to rapid-eye-movement (REM) sleep can be understood as a first-order phase transition from a low-firing, coherent state to a high-firing, desychronized cortical state. We show that the model predictions for changes in EEG power, spectral distribution, and correlation time at the SWS-to-REM transition are consistent not only with those observed in clinical recordings of a sleeping human subject, but also with the on-cortex EEG patterns recently reported by Destexhe et al. [J. Neurosci. 19(11), (1999) 4595–4608] for the sleeping cat.

text: The sleep cycle modelled as a cortical phase transition We present a mean-field model of the cortex that attempts to describe the gross changes in brain electrical activity for the cycles of natural sleep. We incorporate within the model two major sleep modulatory effects: slow changes in both synaptic efficiency and in neuron resting voltage caused by the ∼90-min cycling in acetylcholine, together with even slower changes in resting voltage caused by gradual elimination during sleep of somnogens (fatigue agents) such as adenosine. We argue that the change from slow-wave sleep (SWS) to rapid-eye-movement (REM) sleep can be understood as a first-order phase transition from a low-firing, coherent state to a high-firing, desychronized cortical state. We show that the model predictions for changes in EEG power, spectral distribution, and correlation time at the SWS-to-REM transition are consistent not only with those observed in clinical recordings of a sleeping human subject, but also with the on-cortex EEG patterns recently reported by Destexhe et al. [J. Neurosci. 19(11), (1999) 4595–4608] for the sleeping cat.

year: 2005-12

title: The operation of public benefit in New Zealand - meeting contemporary challenges?

authors: Chevalier-Watts, Juliet

abstract: Much has been written about the concept of public benefit in charity law, and the quantity of judicial and academic commentary on this concept is indicative of its challenging and often nebulous character. This article considers public benefit and charity law from a New Zealand perspective and it will illustrate that the New Zealand courts are not afraid to address controversial or challenging circumstances relating to these matters. Indeed, such cases reflect the ability of the courts to meet the contemporary challenges of determining public benefit.

text: The operation of public benefit in New Zealand - meeting contemporary challenges? Much has been written about the concept of public benefit in charity law, and the quantity of judicial and academic commentary on this concept is indicative of its challenging and often nebulous character. This article considers public benefit and charity law from a New Zealand perspective and it will illustrate that the New Zealand courts are not afraid to address controversial or challenging circumstances relating to these matters. Indeed, such cases reflect the ability of the courts to meet the contemporary challenges of determining public benefit.

year: 2015

title: Te Whakatōhea Maurua

authors: Maxwell, Te Kahautu

abstract: Te Whakatōhea Maurua is a Whakaeke item that was composed to commemorate the rangatira of Te Whakatōhea that lost their lives in the colonial wars of the mid nineteenth century at the hands of the Te Arawa people who were loyalists to the Crown. This composition was composed also to bury the hatchet between Te Whakatōhea and Te Arawa. This composition was performed by Ōpōtiki Mai Tawhiti at the Te Matatini World Championship Kapa Haka Competition 2013

text: Te Whakatōhea Maurua Te Whakatōhea Maurua is a Whakaeke item that was composed to commemorate the rangatira of Te Whakatōhea that lost their lives in the colonial wars of the mid nineteenth century at the hands of the Te Arawa people who were loyalists to the Crown. This composition was composed also to bury the hatchet between Te Whakatōhea and Te Arawa. This composition was performed by Ōpōtiki Mai Tawhiti at the Te Matatini World Championship Kapa Haka Competition 2013

year: 2013