title: Cortical entropy changes with general anaesthesia: theory and experiment

authors: Sleigh, James W.

subjects: electroencephalography

abstract: Commonly used general anaesthetics cause a decrease in the spectral entropy of the electroencephalogram as the patient transits from the conscious to the unconscious state. Although the spectral entropy is a configurational entropy, it is plausible that the spectral entropy may be acting as a reliable indicator of real changes in cortical neuronal interactions. Using a mean field theory, the activity of the cerebral cortex may be modelled as fluctuations in mean soma potential around equilibrium states. In the adiabatic limit, the stochastic differential equations take the form of an Ornstein–Uhlenbeck process. It can be shown that spectral entropy is a logarithmic measure of the rate of synaptic interaction. This model predicts that the spectral entropy should decrease abruptly from values ~1.0 to values of ~0.7 as the patient becomes unconscious during induction of general anaesthesia, and then not decrease significantly on further deepening of anaesthesia. These predictions were compared with experimental results in which electrocorticograms and brain concentrations of propofol were recorded in seven sheep during induction of anaesthesia with intravenous propofol. The observed changes in spectral entropy agreed with the theoretical predictions. We conclude that spectral entropy may be a sensitive monitor of the consciousness–unconsciousness transition, rather than a progressive indicator of anaesthetic drug effect.

text: Cortical entropy changes with general anaesthesia: theory and experiment Commonly used general anaesthetics cause a decrease in the spectral entropy of the electroencephalogram as the patient transits from the conscious to the unconscious state. Although the spectral entropy is a configurational entropy, it is plausible that the spectral entropy may be acting as a reliable indicator of real changes in cortical neuronal interactions. Using a mean field theory, the activity of the cerebral cortex may be modelled as fluctuations in mean soma potential around equilibrium states. In the adiabatic limit, the stochastic differential equations take the form of an Ornstein–Uhlenbeck process. It can be shown that spectral entropy is a logarithmic measure of the rate of synaptic interaction. This model predicts that the spectral entropy should decrease abruptly from values ~1.0 to values of ~0.7 as the patient becomes unconscious during induction of general anaesthesia, and then not decrease significantly on further deepening of anaesthesia. These predictions were compared with experimental results in which electrocorticograms and brain concentrations of propofol were recorded in seven sheep during induction of anaesthesia with intravenous propofol. The observed changes in spectral entropy agreed with the theoretical predictions. We conclude that spectral entropy may be a sensitive monitor of the consciousness–unconsciousness transition, rather than a progressive indicator of anaesthetic drug effect.

year: 2004

title: Perceptions of Chinese Hotels

authors: Ryan, Chris

subjects: Chinese hotels

abstract: The evaluations of 941 respondents who had recently stayed in a Chinese hotel revealed that guests' satisfaction with the hotels were influenced by hotels' star ratings. By comparing the importance-evaluation matrices for each category of hotel, a clear trend emerges in which higher levels of satisfaction are discernable for five-star and deluxe hotels than for one- and two-star hotels. At all levels, however, respondents gave high ratings to the key attributes of cleanliness and bed comfort. The findings raise a question of how to ensure satisfaction for China's one- and two-star hotels.

text: Perceptions of Chinese Hotels The evaluations of 941 respondents who had recently stayed in a Chinese hotel revealed that guests' satisfaction with the hotels were influenced by hotels' star ratings. By comparing the importance-evaluation matrices for each category of hotel, a clear trend emerges in which higher levels of satisfaction are discernable for five-star and deluxe hotels than for one- and two-star hotels. At all levels, however, respondents gave high ratings to the key attributes of cleanliness and bed comfort. The findings raise a question of how to ensure satisfaction for China's one- and two-star hotels.

year: 2007

title: Nga taonga o Te Urewera

authors: Te Awekotuku, Ngahuia

subjects: Maori

abstract: This report sets out to establish that Te Urewera and Tuhoe - the place, the people -
are synonymous. It is argued by two discrete approaches - cultural property and the
significance of place. These are both enmeshed in the Tuhoe concept of
matemateaone, which is defined and demonstrated throughout the text. Issues of
Tuhoe heritage and cultural property are positioned within the international
indigenous context, and considered in detail with reference to the United Nations
Report on the Protection of the Heritage of Indigenous Peoples tabled in June 1995.
A Tuhoe response to the nine sections of this document form the basis of this
submission, as they clearly reflect the intentions and principles that configure the
articles of the Treaty of Waitangi.

text: Nga taonga o Te Urewera This report sets out to establish that Te Urewera and Tuhoe - the place, the people -
are synonymous. It is argued by two discrete approaches - cultural property and the
significance of place. These are both enmeshed in the Tuhoe concept of
matemateaone, which is defined and demonstrated throughout the text. Issues of
Tuhoe heritage and cultural property are positioned within the international
indigenous context, and considered in detail with reference to the United Nations
Report on the Protection of the Heritage of Indigenous Peoples tabled in June 1995.
A Tuhoe response to the nine sections of this document form the basis of this
submission, as they clearly reflect the intentions and principles that configure the
articles of the Treaty of Waitangi.

year: 2003-08