title: Carbon dioxide exchange in lichens: Relationship between the diffusive resistance of carbon dioxide and water vapour

authors: Green, T.G. Allan

abstract: Gaseous diffusion resistances for carbon dioxide and water vapour, thallus water content and thallus water potential were experimentally determined on species of the Stictaceae. The diffusion resistance to water loss was high only at low water contents and correlated closely with thallus water potential. Carbon dioxide diffusion resistances, however, were high at both low and high water contents and, even at medium water contents, were still an order of magnitude greater than the water resistance. These results indicate that carbon dioxide and water vapour exchange occur by different pathways in these lichens. Consequently it is suggested that the lichens have structural adaptations which separate the functions of water uptake, water storage and carbon dioxide exchange.

text: Carbon dioxide exchange in lichens: Relationship between the diffusive resistance of carbon dioxide and water vapour Gaseous diffusion resistances for carbon dioxide and water vapour, thallus water content and thallus water potential were experimentally determined on species of the Stictaceae. The diffusion resistance to water loss was high only at low water contents and correlated closely with thallus water potential. Carbon dioxide diffusion resistances, however, were high at both low and high water contents and, even at medium water contents, were still an order of magnitude greater than the water resistance. These results indicate that carbon dioxide and water vapour exchange occur by different pathways in these lichens. Consequently it is suggested that the lichens have structural adaptations which separate the functions of water uptake, water storage and carbon dioxide exchange.

year: 1982

title: Prior Robustness for Bayesian Implementation of the Fault Tree Analysis

authors: Joshi, Chaitanya

subjects: Science & Technology

abstract: We propose a prior robustness approach for the Bayesian implementation of the fault tree analysis (FTA). FTA is often used to evaluate risk in large, safety critical systems but has limitations due to its static structure. Bayesian approaches have been proposed as a superior alternative to it, however, this involves prior elicitation, which is not straightforward. We show that minor misspecification of priors for elementary events can result in a significant prior misspecification for the top event. A large amount of data is required to correctly update a misspecified prior and such data may not be available for many complex, safety critical systems. In such cases, prior misspecification equals posterior misspecification. Therefore, there is a need to develop a robustness approach for FTA, which can quantify the effects of prior misspecification on the posterior analysis. Here, we propose the first prior robustness approach specifically developed for FTA. We not only prove a few important mathematical properties of this approach, but also develop easy to use Monte Carlo sampling algorithms to implement this approach on any given fault tree with and and/or or gates. We then implement this Bayesian robustness approach on two real-life examples: a spacecraft re-entry example and a feeding control system example. We also provide a step-by-step illustration of how this approach can be applied to a real-life problem.

text: Prior Robustness for Bayesian Implementation of the Fault Tree Analysis We propose a prior robustness approach for the Bayesian implementation of the fault tree analysis (FTA). FTA is often used to evaluate risk in large, safety critical systems but has limitations due to its static structure. Bayesian approaches have been proposed as a superior alternative to it, however, this involves prior elicitation, which is not straightforward. We show that minor misspecification of priors for elementary events can result in a significant prior misspecification for the top event. A large amount of data is required to correctly update a misspecified prior and such data may not be available for many complex, safety critical systems. In such cases, prior misspecification equals posterior misspecification. Therefore, there is a need to develop a robustness approach for FTA, which can quantify the effects of prior misspecification on the posterior analysis. Here, we propose the first prior robustness approach specifically developed for FTA. We not only prove a few important mathematical properties of this approach, but also develop easy to use Monte Carlo sampling algorithms to implement this approach on any given fault tree with and and/or or gates. We then implement this Bayesian robustness approach on two real-life examples: a spacecraft re-entry example and a feeding control system example. We also provide a step-by-step illustration of how this approach can be applied to a real-life problem.

year: 2018

title: Upsetting Geographies: Sacred Spaces of Matata

authors: Brown, Keri Aroha Michelle

subjects: sacred

abstract: My research focuses on the emotional experience of the unearthing of ancestral bones for local Māori of Matata. The coastal town of Matata in the Eastern Bay of Plenty provides a central case study location as it is a town that is facing the pressure of coastal residential development as well the added strain of dealing with the 2005 flood which has compounded issues over local waahi tapu.  Local iwi have continued to actively advocate for the protection of these sites especially with regard to the ongoing discovery of ancestral bones.

Cultural and emotional geographies provide the theoretical framework for this research. This framework has been particularly useful as it encourages reflexive commentary and alternative ways of approaching and thinking about, and understanding knowledge. I have incorporated the research paradigm of kaupapa Māori which complements my theoretical framework by producing a research design that is organised and shaped according to tikanga Māori while (in) advertently critiquing and challenging traditional ways of conducting research. The overall aim is to explore the current issues surrounding the discovery of ancestral bones through korero with local iwi members. It is through their perspectives, stories, beliefs and opinions that provide a better understanding of the meanings attributed to waahi tapu and the influence of certain events such as the 2005 flood. I examine, critically the relationship between power, sacred sites, bones and the body. 

It is from these objectives that I contribute to an area of scholarship that has been largely left out from geographical enquiry. I suggest that the importance of sacredness and spirituality has been relatively overlooked as an influential factor in people's perceptions of the world around them. This thesis is intended to demonstrate the value of indigenous perspectives of bones, the body and sacredness as a way of better understanding some of the complexities that can arise when cross-cultural approaches collide in environmental planning.  

There are three main themes that have emerged from this research. The first theme has to do with competing knowledges. To Māori, the location and knowledge of ancestral bones is culturally important and is in its self sacred, therefore certain tikanga is applied as a means of a protection mechanism. However this ideologically clashes with traditional scientific western approaches which are privileged over other alternative ways of understanding knowledge, in this case Māori knowledge. The second related theme concerns the process of boundary making and cross-cultural ways of perceiving 'sacred' and 'everyday' spaces. To better understand these perspectives involves acknowledging the embodied and emotional experience of wāhi tapu to Māori, and the active role of kaitiaki in the protection and careful management of these culturally important spaces.

text: Upsetting Geographies: Sacred Spaces of Matata My research focuses on the emotional experience of the unearthing of ancestral bones for local Māori of Matata. The coastal town of Matata in the Eastern Bay of Plenty provides a central case study location as it is a town that is facing the pressure of coastal residential development as well the added strain of dealing with the 2005 flood which has compounded issues over local waahi tapu.  Local iwi have continued to actively advocate for the protection of these sites especially with regard to the ongoing discovery of ancestral bones.

Cultural and emotional geographies provide the theoretical framework for this research. This framework has been particularly useful as it encourages reflexive commentary and alternative ways of approaching and thinking about, and understanding knowledge. I have incorporated the research paradigm of kaupapa Māori which complements my theoretical framework by producing a research design that is organised and shaped according to tikanga Māori while (in) advertently critiquing and challenging traditional ways of conducting research. The overall aim is to explore the current issues surrounding the discovery of ancestral bones through korero with local iwi members. It is through their perspectives, stories, beliefs and opinions that provide a better understanding of the meanings attributed to waahi tapu and the influence of certain events such as the 2005 flood. I examine, critically the relationship between power, sacred sites, bones and the body. 

It is from these objectives that I contribute to an area of scholarship that has been largely left out from geographical enquiry. I suggest that the importance of sacredness and spirituality has been relatively overlooked as an influential factor in people's perceptions of the world around them. This thesis is intended to demonstrate the value of indigenous perspectives of bones, the body and sacredness as a way of better understanding some of the complexities that can arise when cross-cultural approaches collide in environmental planning.  

There are three main themes that have emerged from this research. The first theme has to do with competing knowledges. To Māori, the location and knowledge of ancestral bones is culturally important and is in its self sacred, therefore certain tikanga is applied as a means of a protection mechanism. However this ideologically clashes with traditional scientific western approaches which are privileged over other alternative ways of understanding knowledge, in this case Māori knowledge. The second related theme concerns the process of boundary making and cross-cultural ways of perceiving 'sacred' and 'everyday' spaces. To better understand these perspectives involves acknowledging the embodied and emotional experience of wāhi tapu to Māori, and the active role of kaitiaki in the protection and careful management of these culturally important spaces.

year: 2008