title: EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory.

authors: Wang, Kaier

subjects: Turing–Hopf instabilities

abstract: The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing-Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05-1.5 Hz) slow-wave coherence between frontal, occipital, and frontal-occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex.

text: EEG slow-wave coherence changes in propofol-induced general anesthesia: experiment and theory. The electroencephalogram (EEG) patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. (2013) proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing) and time (Hopf), modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing-Hopf balance (wake) to Hopf-dominated chaotic slow-waves (unconsciousness). Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05-1.5 Hz) slow-wave coherence between frontal, occipital, and frontal-occipital electrode pairs, with the most pronounced wake-vs.-unconscious coherence changes occurring at the frontal cortex.

year: 2014

title: Combining Capabilities: A Resource Based Model of ICT Advantage

authors: Rastrick, Karyn Christine

subjects: resource based view

abstract: Significant levels of interest and organisational spending on information and communication technologies (ICT's) have triggered debate as to whether these investments are worthwhile.  While there has been some acknowledgement that investments result in positive returns, little is known about how ICT's may lead to competitive advantage.  This thesis starts to inform this gap, by investigating how ICT's are combined with other organisational resources in the context of an exemplar organisation.  The resource based view (RBV) is used as a framework to guide this study.  The RBV is an appropriate lens to guide this research due to its focus on resources and capabilities as sources of advantage.  This research employs an interpretive case study design based in an organisation with a long history of innovation and success with regard to ICT's.  

A grounded integrated model of advantage is presented based on two distinct groupings of integrated capabilities: lifecycle and embedded foundational capabilities.  The integrated model of advantage, along with key actions outlined to support such capabilities, provides researchers and practitioners with a new way of understanding ICT based advantages.  In essence, this research demonstrates how the total ownership of ICT's, within the case studied, presents a potential advantage.  The advantage is realised through the combination of capabilities and the inclusive approach to ICT development employed in the case organisation.  The research finds support from propositions of the RBV, in that the model demonstrates sources of advantage are based on organisational capabilities which are valuable, firm specific, and socially complex.  As such, the integration of capabilities evident in the integrated model of advantage is a likely source of sustained competitive advantage.  This means advantages gained from the integration of capabilities are not easily imitated or competed away.  Furthermore, advantages have an even greater potential to be a source of sustained advantage than any single resource or capability.  The research has important implications for theory and practice.  While many individual sources of advantage have been empirically examined, this research provides one of the first in-depth case studies which identify integrated capabilities.  Understanding such sources of advantage will help practitioners better understand and protect key organisational capabilities to sustain or extend competitive advantages.

text: Combining Capabilities: A Resource Based Model of ICT Advantage Significant levels of interest and organisational spending on information and communication technologies (ICT's) have triggered debate as to whether these investments are worthwhile.  While there has been some acknowledgement that investments result in positive returns, little is known about how ICT's may lead to competitive advantage.  This thesis starts to inform this gap, by investigating how ICT's are combined with other organisational resources in the context of an exemplar organisation.  The resource based view (RBV) is used as a framework to guide this study.  The RBV is an appropriate lens to guide this research due to its focus on resources and capabilities as sources of advantage.  This research employs an interpretive case study design based in an organisation with a long history of innovation and success with regard to ICT's.  

A grounded integrated model of advantage is presented based on two distinct groupings of integrated capabilities: lifecycle and embedded foundational capabilities.  The integrated model of advantage, along with key actions outlined to support such capabilities, provides researchers and practitioners with a new way of understanding ICT based advantages.  In essence, this research demonstrates how the total ownership of ICT's, within the case studied, presents a potential advantage.  The advantage is realised through the combination of capabilities and the inclusive approach to ICT development employed in the case organisation.  The research finds support from propositions of the RBV, in that the model demonstrates sources of advantage are based on organisational capabilities which are valuable, firm specific, and socially complex.  As such, the integration of capabilities evident in the integrated model of advantage is a likely source of sustained competitive advantage.  This means advantages gained from the integration of capabilities are not easily imitated or competed away.  Furthermore, advantages have an even greater potential to be a source of sustained advantage than any single resource or capability.  The research has important implications for theory and practice.  While many individual sources of advantage have been empirically examined, this research provides one of the first in-depth case studies which identify integrated capabilities.  Understanding such sources of advantage will help practitioners better understand and protect key organisational capabilities to sustain or extend competitive advantages.

year: 2008

title: The Te Aroha hot springs (mainly in the nineteenth century)

authors: Hart, Philip

abstract: Unique amongst New Zealand mining districts, the hot springs sited at the base of the mountain were popular with miners, residents, and an increasing number of visitors. Highly valued by Maori for their medicinal qualities, Pakeha visited them well before gold was discovered. Acquired by the Crown as part of the purchase of the Aroha Block, contention arose over whether the springs had been gifted to the Crown and whether Maori should be charged for using them. The provision of a small but free bath to Ngati Rahiri did not satisfy them.
 After Pakeha settled, the springs were developed and the surrounding domain was landscaped. Analysis of the water by experts produced claims about its curative qualities and many miracle cures were claimed, and the water was bottled until more recent analyses traced the existence of arsenic. Men reputedly skilled in hydropathy and similar ‘sciences’ were appointed to assist those suffering from rheumatism and the like. A local board beautified the area until the domain was taken over by the Tourist Department. Many tourists from throughout New Zealand and abroad were attracted by the facilities, which included a library, but some noticed a lack of cleanliness and were annoyed by larrikins. Despite such problems, as mining faded Te Aroha profited from becoming a tourist destination and sanatorium.

text: The Te Aroha hot springs (mainly in the nineteenth century) Unique amongst New Zealand mining districts, the hot springs sited at the base of the mountain were popular with miners, residents, and an increasing number of visitors. Highly valued by Maori for their medicinal qualities, Pakeha visited them well before gold was discovered. Acquired by the Crown as part of the purchase of the Aroha Block, contention arose over whether the springs had been gifted to the Crown and whether Maori should be charged for using them. The provision of a small but free bath to Ngati Rahiri did not satisfy them.
 After Pakeha settled, the springs were developed and the surrounding domain was landscaped. Analysis of the water by experts produced claims about its curative qualities and many miracle cures were claimed, and the water was bottled until more recent analyses traced the existence of arsenic. Men reputedly skilled in hydropathy and similar ‘sciences’ were appointed to assist those suffering from rheumatism and the like. A local board beautified the area until the domain was taken over by the Tourist Department. Many tourists from throughout New Zealand and abroad were attracted by the facilities, which included a library, but some noticed a lack of cleanliness and were annoyed by larrikins. Despite such problems, as mining faded Te Aroha profited from becoming a tourist destination and sanatorium.

year: 2016