title: Theoretical Investigation of NMDA Effect on the Cerebral Cortex

authors: AL Saidi, Waleed Hamdan Khalfan

subjects: NMDA  Effect

abstract: This thesis examines the dynamical behaviour of incorporating NMDA (an excitatory
neurotransmitter) for the electrodynamic model of the cerebral cortex. The
model used is the mean-field model developed by Steyn-Ross et al. (2005) which
describes the behaviour of the cortex in terms of parameters averaged over spatially
localised populations. The behaviour of the model is determined by the four control
parameters: inhibitory effect li, subcortical drive s, and NMDA neurotransmitter
e ect set by an excitatory factor le and the magnesium concentration C. Adopting
this model could give a better understanding of the cortex functionality and the
anaesthetic mechanism.
The model predicts that there are either one or three stationary states available to
the cortex. We identify two of these with highly activated state and a quiescent
state and focus on the transition between the two. Theoretical stability predictions
(eigenvalue analysis) verified by a numerical simulation show that the system is
unstable between the two Hopf bifurcations. In addition, in the stable region the
steady states remains stable under a small perturbation, while in the unstable region
either a transition between states or a limit cycle (oscillation) occurs depending on
the position of the steady state.

text: Theoretical Investigation of NMDA Effect on the Cerebral Cortex This thesis examines the dynamical behaviour of incorporating NMDA (an excitatory
neurotransmitter) for the electrodynamic model of the cerebral cortex. The
model used is the mean-field model developed by Steyn-Ross et al. (2005) which
describes the behaviour of the cortex in terms of parameters averaged over spatially
localised populations. The behaviour of the model is determined by the four control
parameters: inhibitory effect li, subcortical drive s, and NMDA neurotransmitter
e ect set by an excitatory factor le and the magnesium concentration C. Adopting
this model could give a better understanding of the cortex functionality and the
anaesthetic mechanism.
The model predicts that there are either one or three stationary states available to
the cortex. We identify two of these with highly activated state and a quiescent
state and focus on the transition between the two. Theoretical stability predictions
(eigenvalue analysis) verified by a numerical simulation show that the system is
unstable between the two Hopf bifurcations. In addition, in the stable region the
steady states remains stable under a small perturbation, while in the unstable region
either a transition between states or a limit cycle (oscillation) occurs depending on
the position of the steady state.

year: 2008

title: Not so scholarly but certainly on-message: the leadership BES and its significant silences

authors: Thrupp, Martin

subjects: New Zealand

abstract: This article suggests that the Leadership BES is intended to provide the intellectual underpinning for the Ministry of Education's preferred model of school leadership in New Zealand. Nevertheless, the instrumental 'what works' approach taken by the BES represents only a constrained and conservative research agenda which leaves out structural and political perspectives on school leadership. A number of points drawn from the introductory and main chapters of the BES are used to illustrate the problem. The article concludes by noting topics and authors which would have provided balance if included in the BES.

text: Not so scholarly but certainly on-message: the leadership BES and its significant silences This article suggests that the Leadership BES is intended to provide the intellectual underpinning for the Ministry of Education's preferred model of school leadership in New Zealand. Nevertheless, the instrumental 'what works' approach taken by the BES represents only a constrained and conservative research agenda which leaves out structural and political perspectives on school leadership. A number of points drawn from the introductory and main chapters of the BES are used to illustrate the problem. The article concludes by noting topics and authors which would have provided balance if included in the BES.

year: 2010

title: "Thereness": Implications of Heidegger's "presence" for Māori

authors: Mika, Carl Te Hira

abstract: For Māori, the philosophical consequences of colonization are a hugely important issue, due to both the subtlety and the omnipresence of Western metaphysics. In this article I refer to the “meta-physics of presence” through one major Western thinker—Martin Heidegger—who identified “presence” as a problem for the West. He proposes that the metaphysics of presence underpins every perception in the West and that it is the fundamental mistake of philosophers since Plato but becoming ascendant with Aristotle. I identify the points of relevance within their claims and refer them to a Māori understanding of absence. I also consider the more affective nature of Western presence, which Heidegger refers to but which must be theorized by Māori. In the first instance I place particular emphasis on the ironies implicit in writing about metaphysics for the Māori writer in the academy and for the things being represented in that writing. Finally, the metaphysics of presence opens up possibilities for its own instability; this Heideggerean “saving power” is discussed in Māori terms.

text: "Thereness": Implications of Heidegger's "presence" for Māori For Māori, the philosophical consequences of colonization are a hugely important issue, due to both the subtlety and the omnipresence of Western metaphysics. In this article I refer to the “meta-physics of presence” through one major Western thinker—Martin Heidegger—who identified “presence” as a problem for the West. He proposes that the metaphysics of presence underpins every perception in the West and that it is the fundamental mistake of philosophers since Plato but becoming ascendant with Aristotle. I identify the points of relevance within their claims and refer them to a Māori understanding of absence. I also consider the more affective nature of Western presence, which Heidegger refers to but which must be theorized by Māori. In the first instance I place particular emphasis on the ironies implicit in writing about metaphysics for the Māori writer in the academy and for the things being represented in that writing. Finally, the metaphysics of presence opens up possibilities for its own instability; this Heideggerean “saving power” is discussed in Māori terms.

year: 2015