title: Modelling general anaesthesia as a first-order phase transition in the cortex

authors: Steyn-Ross, Moira L.

subjects: anaesthesia

abstract: Since 1997 we have been developing a theoretical foundation for general anaesthesia. We have been able to demonstrate that the abrupt change in brain state broughton by anaesthetic drugs can be characterized as a first-order phase transition in the population-average membrane voltage of the cortical neurons. The theory predicts that, as the critical point of phase-change into unconsciousness is approached, the electrical fluctuations in cortical activity will grow strongly in amplitude while slowing in frequency, becoming more correlated both in time and in space. Thus the bio-electrical change of brain-state has deep similarities with thermodynamic phase changes of classical physics. The theory further predicts the existence of a second critical point, hysteretically separated from the first, corresponding to the return path from comatose unconsciousness back to normal responsiveness. There is a steadily accumulating body of clinical evidence in support of all of the phasetransition predictions: low-frequency power surge in EEG activity; increased correlation time and correlation length in EEG fluctuations; hysteresis separation, with respect to drug concentration, between the point of induction and the point of emergence.

text: Modelling general anaesthesia as a first-order phase transition in the cortex Since 1997 we have been developing a theoretical foundation for general anaesthesia. We have been able to demonstrate that the abrupt change in brain state broughton by anaesthetic drugs can be characterized as a first-order phase transition in the population-average membrane voltage of the cortical neurons. The theory predicts that, as the critical point of phase-change into unconsciousness is approached, the electrical fluctuations in cortical activity will grow strongly in amplitude while slowing in frequency, becoming more correlated both in time and in space. Thus the bio-electrical change of brain-state has deep similarities with thermodynamic phase changes of classical physics. The theory further predicts the existence of a second critical point, hysteretically separated from the first, corresponding to the return path from comatose unconsciousness back to normal responsiveness. There is a steadily accumulating body of clinical evidence in support of all of the phasetransition predictions: low-frequency power surge in EEG activity; increased correlation time and correlation length in EEG fluctuations; hysteresis separation, with respect to drug concentration, between the point of induction and the point of emergence.

year: 2004-01

title: Do loyalty programs really enhance behavioral loyalty? An empirical analysis accounting for self-selecting members

authors: Leenheer, Jorna

subjects: loyalty programs

abstract: One of the pressing issues in marketing is whether loyalty programs really enhance behavioral loyalty. Loyalty program members may have a much higher share-of-wallet at the firm with the loyalty program than non-members have, but this does not necessarily imply that loyalty programs are effective. Loyal customers may select themselves to become members in order to benefit from the program. Since this implies that program membership is endogenous, we estimate models for both the membership decision (using instrumental variables) and for the effect of membership on share-of-wallet, our measure of behavioral loyalty. We use panel data from a representative sample of Dutch households who report their loyalty program memberships for all seven loyalty programs in grocery retailing as well as their expenditures at each of the 20 major supermarket chains. We find a small positive yet significant effect of loyalty program membership on share-of-wallet. This effect is seven times smaller than is suggested by a naïve model that ignores the endogeneity of program membership. The predictive validity of the proposed model is much better than for the naïve model. Our results show that creating loyalty program membership is a crucial step to enhance share-of-wallet, and we provide guidelines on how to achieve this.

text: Do loyalty programs really enhance behavioral loyalty? An empirical analysis accounting for self-selecting members One of the pressing issues in marketing is whether loyalty programs really enhance behavioral loyalty. Loyalty program members may have a much higher share-of-wallet at the firm with the loyalty program than non-members have, but this does not necessarily imply that loyalty programs are effective. Loyal customers may select themselves to become members in order to benefit from the program. Since this implies that program membership is endogenous, we estimate models for both the membership decision (using instrumental variables) and for the effect of membership on share-of-wallet, our measure of behavioral loyalty. We use panel data from a representative sample of Dutch households who report their loyalty program memberships for all seven loyalty programs in grocery retailing as well as their expenditures at each of the 20 major supermarket chains. We find a small positive yet significant effect of loyalty program membership on share-of-wallet. This effect is seven times smaller than is suggested by a naïve model that ignores the endogeneity of program membership. The predictive validity of the proposed model is much better than for the naïve model. Our results show that creating loyalty program membership is a crucial step to enhance share-of-wallet, and we provide guidelines on how to achieve this.

year: 2007

title: Kia Maanu, Kia Ora: Stay Afloat, Stay Alive – Acknowledging the significance of tikanga Māori in formulating and communicating water safety policies and practices

authors: Haimona, Mark

subjects: New Zealand

abstract: The traditional beliefs and practices of Māori demonstrate great respect for water, for its dangers as well as its life-giving properties, and Māori have, along with other Polynesian peoples, been known for their skill in swimming, fishing and canoeing. However, Māori now outnumber others in New Zealand in terms of the proportion involved in drowning and water-related injury. In seeking to promote water safety among Māori, Water Safety New Zealand has enlisted the help of Māori communities. Its message - Kia Maanu, Kia Ora (Stay Afloat, Stay Alive) - is underpinned by an acknowledgment of the need to reinforce the traditional respect for water that permeates the Māori worldview.

text: Kia Maanu, Kia Ora: Stay Afloat, Stay Alive – Acknowledging the significance of tikanga Māori in formulating and communicating water safety policies and practices The traditional beliefs and practices of Māori demonstrate great respect for water, for its dangers as well as its life-giving properties, and Māori have, along with other Polynesian peoples, been known for their skill in swimming, fishing and canoeing. However, Māori now outnumber others in New Zealand in terms of the proportion involved in drowning and water-related injury. In seeking to promote water safety among Māori, Water Safety New Zealand has enlisted the help of Māori communities. Its message - Kia Maanu, Kia Ora (Stay Afloat, Stay Alive) - is underpinned by an acknowledgment of the need to reinforce the traditional respect for water that permeates the Māori worldview.

year: 2007