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: Travel recommendations in a mobile tourist information system

authors: Hinze, Annika

subjects: computer science

abstract: An advanced mobile tourist information system delivers information about sights and events on a tourists travel route. The system should be personalized in its interaction with the tourist. Data that can be used for personalization are: the tourists interest profile, an analysis of their travel history, and the tourists feedback about sights. Existing mobile information systems for tourists do not tailor their information delivery to the tourists interests. In this paper, we propose the use of personalised recommendations that consider all of the personal information a tourist provides. We adopt and modify techniques from recommended systems to the new application area of mobile tourist information. We propose a number of methods for personalised recommendations; and select a subset of these for implementation. This paper then presents the implemented recommended component of our TIP system for mobile tourist information

text: Travel recommendations in a mobile tourist information system An advanced mobile tourist information system delivers information about sights and events on a tourists travel route. The system should be personalized in its interaction with the tourist. Data that can be used for personalization are: the tourists interest profile, an analysis of their travel history, and the tourists feedback about sights. Existing mobile information systems for tourists do not tailor their information delivery to the tourists interests. In this paper, we propose the use of personalised recommendations that consider all of the personal information a tourist provides. We adopt and modify techniques from recommended systems to the new application area of mobile tourist information. We propose a number of methods for personalised recommendations; and select a subset of these for implementation. This paper then presents the implemented recommended component of our TIP system for mobile tourist information

year: 2005-05-23

title: Hauora and physical education in New Zealand: perspectives of Māori and Pasifika

authors: Fitzpatrick, Katie

subjects: physical education

abstract: Discussion surrounding the concept of Hauora (Durie, 1994) in the document Health and Physical Education in the New Zealand Curriculum (Ministry of Education, 1999) has been controversial. Some writers have praised or justified its inclusion (Culpan, 1996/1997; Tasker, 1996/1997; Tinning, MacDonald, Wright & Hickey, 2001), while others accuse the writers of tokenism and misappropriation of indigenous knowledge (Hokowhitu, 2004; Salter, 2000). While existing at a political level, these debates have generally ignored student responses to and interactions with Hauora. Thus, this article intervenes in the existing debate and makes the case for the inclusion of student perspectives. My claims are made on the basis of a study into the perspectives of Māori and Pasifika students of physical education in New Zealand. The experiences of these students are related to the theory of hybridity (Besley, 2002; Bhabha, 1994), which suggests that young people actively negotiate and make critical decisions about what they think is relevant to them. I argue that the debate surrounding the concept of Hauora needs to include students' perspectives and consideration of the agency of young people in interactions with curriculum concepts.

text: Hauora and physical education in New Zealand: perspectives of Māori and Pasifika Discussion surrounding the concept of Hauora (Durie, 1994) in the document Health and Physical Education in the New Zealand Curriculum (Ministry of Education, 1999) has been controversial. Some writers have praised or justified its inclusion (Culpan, 1996/1997; Tasker, 1996/1997; Tinning, MacDonald, Wright & Hickey, 2001), while others accuse the writers of tokenism and misappropriation of indigenous knowledge (Hokowhitu, 2004; Salter, 2000). While existing at a political level, these debates have generally ignored student responses to and interactions with Hauora. Thus, this article intervenes in the existing debate and makes the case for the inclusion of student perspectives. My claims are made on the basis of a study into the perspectives of Māori and Pasifika students of physical education in New Zealand. The experiences of these students are related to the theory of hybridity (Besley, 2002; Bhabha, 1994), which suggests that young people actively negotiate and make critical decisions about what they think is relevant to them. I argue that the debate surrounding the concept of Hauora needs to include students' perspectives and consideration of the agency of young people in interactions with curriculum concepts.

year: 2005