title: Maori children and death: Views from parents

authors: Jacob, Juanita

subjects: Maori

abstract: Research about Maori children's experiences and perceptions of death and tangi (Maori death rituals) is sparse. What is available tends to be generalised and stems from Western paradigms of knowledge. In this study we explore Maori children's experiences of death and tangi through the eyes of Maori parents. Through semi-structured interviews with 17 Maori parents, five areas were explored: a) the childhood experiences of parents and how they learned about death and an afterlife; b) what their adult beliefs about these matters are; c) how they have communicated the death concept to their children; and d) whether their children are likely to do the same in the future. From this study we learn that death was not hidden from children, that parents talked with their children in very open and age relevant ways, and considered their children's participation in tangi an important way to grieve and ensure continuity with kinship networks and support. This study suggests that the challenge now is to ensure that these practices continue to persist between parents and their children, and future generations.

text: Maori children and death: Views from parents Research about Maori children's experiences and perceptions of death and tangi (Maori death rituals) is sparse. What is available tends to be generalised and stems from Western paradigms of knowledge. In this study we explore Maori children's experiences of death and tangi through the eyes of Maori parents. Through semi-structured interviews with 17 Maori parents, five areas were explored: a) the childhood experiences of parents and how they learned about death and an afterlife; b) what their adult beliefs about these matters are; c) how they have communicated the death concept to their children; and d) whether their children are likely to do the same in the future. From this study we learn that death was not hidden from children, that parents talked with their children in very open and age relevant ways, and considered their children's participation in tangi an important way to grieve and ensure continuity with kinship networks and support. This study suggests that the challenge now is to ensure that these practices continue to persist between parents and their children, and future generations.

year: 2011-12

title: Contrasting microbial communities across anthropogenic pollution gradients: MV Rena shipwreck versus urban pressures

authors: Reihana, Kiri

subjects: microbial

abstract: With the catastrophic environmental event that was the MV Rena ship wreck and oil spill in the Bay of Plenty area in 2011, a serendipitous opportunity to laterally explore a variety of impacts in the marine biosphere emerged. One of those opportunities is studied here; how microbial communities respond to stress in context of existing ambient local anthropogenic influences. The locational backdrop to this study is also relevant and provides an additional element of complexity as the Bay of Plenty region is located in the middle of the Taupo Volcanic Zone, hence microbial communities are likely to reflect the regional geology. Therefore a research project was possible where a pollutant gradient was selected based on a range of locations reflecting different elements of natural versus human long term and acute impact stresses. The concept was to establish a platform of preliminary study from which more detailed could follow. In addition this study aimed at providing a link between microbial environmental responses to stress in a context that could permit uptake of scientific evidence for cultural impact assessments given the strong cultural focus on MV Rena impacts by government and the public.
A significant element of the exploratory process was to identify methodologies which may be of use in ascribing microbial community composition with the microenvironment in a manner that allows comparison with research reported in the literature.
Review of all results showed that sites from widely varying geologies and environmental/stress condition were more similar than was initially predicted. This is in sharp contrast to expectations generated from the literature. 
At the sites of Astrolabe Reef (Otaiti) (impacted by the ship wreck, major oil spill and heavy metal pollution event) and Maketu (impacted by a eutrophic estuary), similar consortia transpired, despite strongly different sources of stress, substantiating the microbial biogeography theory: ‘Everything is everywhere’ and ‘the environment selects’. However at Tauranga Harbour long term human activity appears to have had a significant ‘additional’ effect on microbial communities. Our challenge has hence become one to separate out natural versus a range of anthropogenic stressors. 
Underlying the general overall trends, subtle community effects such as at Astrolabe Reef, which supported significantly different dominant communities to the other two sites. It was expected that Tauranga Harbour and Maketu Estuary (adjacent coastally), would be more similar. Of all the sites one at the impacted Maketu, site 1 (M1) and the impacted Tauranga site 2 (T2), were highly similar at 96% from statistical analysis suggesting, the original assumption of visually similar site characteristics (impacted sites with low residence time and thick algal matts) do support similar microbial communities. Substantiating the theory that ‘everything is everywhere’ at these two sites, even though the variables and elemental composition were dissimilar. 
Rare and abundant species were separated out and analysed to elucidate patterns or trends in the communities. Overall the abundant species clustered, into impacted versus non impacted sites, for the rare species Tauranga and Maketu clustered clearly following the same trend; while the Astrolabe reef sites clustered together. The clear differentiation in the rare species from the Astrolabe reef sites, suggests that those species may make up the endemic bacterial communities at Astrolabe Reef with additional effects of Rena pollution suggested at some of the sites close to the wreck.
A general discussion of the cultural and economic impacts of the Rena oil spill, gave context to the holistic human impacts sustained by the local Māori, specifically the disconnect of their precious livelihoods and unique relationship with the environment. These holistic concepts could compromise a thesis in themselves so in this report their definitions are by no means finite.     
This study attempted to interrelate both cultural, ecological biology and microbiology science components for the purpose of a more comprehensive investigation of microbial responses to the Rena oil spill and contrast these to local anthropogenic pressures. However being the first attempt to catalogue the previously unknown microbial communities in the Bay of Plenty area, meant that sample regimes, techniques, processing and analysis were all experimental. Despite this, effects attributable to the Rena were identified that lay beyond the large scale variability identified for Bay of Plenty microbial community assemblages. 
These research results provide an important primary contribution to microbial understandings in the New Zealand context, and as a baseline mapping exercise for the Bay of Plenty region.

text: Contrasting microbial communities across anthropogenic pollution gradients: MV Rena shipwreck versus urban pressures With the catastrophic environmental event that was the MV Rena ship wreck and oil spill in the Bay of Plenty area in 2011, a serendipitous opportunity to laterally explore a variety of impacts in the marine biosphere emerged. One of those opportunities is studied here; how microbial communities respond to stress in context of existing ambient local anthropogenic influences. The locational backdrop to this study is also relevant and provides an additional element of complexity as the Bay of Plenty region is located in the middle of the Taupo Volcanic Zone, hence microbial communities are likely to reflect the regional geology. Therefore a research project was possible where a pollutant gradient was selected based on a range of locations reflecting different elements of natural versus human long term and acute impact stresses. The concept was to establish a platform of preliminary study from which more detailed could follow. In addition this study aimed at providing a link between microbial environmental responses to stress in a context that could permit uptake of scientific evidence for cultural impact assessments given the strong cultural focus on MV Rena impacts by government and the public.
A significant element of the exploratory process was to identify methodologies which may be of use in ascribing microbial community composition with the microenvironment in a manner that allows comparison with research reported in the literature.
Review of all results showed that sites from widely varying geologies and environmental/stress condition were more similar than was initially predicted. This is in sharp contrast to expectations generated from the literature. 
At the sites of Astrolabe Reef (Otaiti) (impacted by the ship wreck, major oil spill and heavy metal pollution event) and Maketu (impacted by a eutrophic estuary), similar consortia transpired, despite strongly different sources of stress, substantiating the microbial biogeography theory: ‘Everything is everywhere’ and ‘the environment selects’. However at Tauranga Harbour long term human activity appears to have had a significant ‘additional’ effect on microbial communities. Our challenge has hence become one to separate out natural versus a range of anthropogenic stressors. 
Underlying the general overall trends, subtle community effects such as at Astrolabe Reef, which supported significantly different dominant communities to the other two sites. It was expected that Tauranga Harbour and Maketu Estuary (adjacent coastally), would be more similar. Of all the sites one at the impacted Maketu, site 1 (M1) and the impacted Tauranga site 2 (T2), were highly similar at 96% from statistical analysis suggesting, the original assumption of visually similar site characteristics (impacted sites with low residence time and thick algal matts) do support similar microbial communities. Substantiating the theory that ‘everything is everywhere’ at these two sites, even though the variables and elemental composition were dissimilar. 
Rare and abundant species were separated out and analysed to elucidate patterns or trends in the communities. Overall the abundant species clustered, into impacted versus non impacted sites, for the rare species Tauranga and Maketu clustered clearly following the same trend; while the Astrolabe reef sites clustered together. The clear differentiation in the rare species from the Astrolabe reef sites, suggests that those species may make up the endemic bacterial communities at Astrolabe Reef with additional effects of Rena pollution suggested at some of the sites close to the wreck.
A general discussion of the cultural and economic impacts of the Rena oil spill, gave context to the holistic human impacts sustained by the local Māori, specifically the disconnect of their precious livelihoods and unique relationship with the environment. These holistic concepts could compromise a thesis in themselves so in this report their definitions are by no means finite.     
This study attempted to interrelate both cultural, ecological biology and microbiology science components for the purpose of a more comprehensive investigation of microbial responses to the Rena oil spill and contrast these to local anthropogenic pressures. However being the first attempt to catalogue the previously unknown microbial communities in the Bay of Plenty area, meant that sample regimes, techniques, processing and analysis were all experimental. Despite this, effects attributable to the Rena were identified that lay beyond the large scale variability identified for Bay of Plenty microbial community assemblages. 
These research results provide an important primary contribution to microbial understandings in the New Zealand context, and as a baseline mapping exercise for the Bay of Plenty region.

year: 2016

title: Ensembles of restricted Hoeffding trees

authors: Bifet, Albert

subjects: design

abstract: The success of simple methods for classification shows that is is often not necessary to model complex attribute interactions to obtain good classification accuracy on practical problems. In this article, we propose to exploit this phenomenon in the data stream context by building an ensemble of Hoeffding trees that are each limited to a small subset of attributes. In this way, each tree is restricted to model interactions between attributes in its corresponding subset. Because it is not known a priori which attribute subsets are relevant for prediction, we build exhaustive ensembles that consider all possible attribute subsets of a given size. As the resulting Hoeffding trees are not all equally important, we weigh them in a suitable manner to obtain accurate classifications. This is done by combining the log-odds of their probability estimates using sigmoid perceptrons, with one perceptron per class. We propose a mechanism for setting the perceptrons' learning rate using the ADWIN change detection method for data streams, and also use ADWIN to reset ensemble members (i.e., Hoeffding trees) when they no longer perform well. Our experiments show that the resulting ensemble classifier outperforms bagging for data streams in terms of accuracy when both are used in conjunction with adaptive naive Bayes Hoeffding trees, at the expense of runtime and memory consumption. We also show that our stacking method can improve the performance of a bagged ensemble.

text: Ensembles of restricted Hoeffding trees The success of simple methods for classification shows that is is often not necessary to model complex attribute interactions to obtain good classification accuracy on practical problems. In this article, we propose to exploit this phenomenon in the data stream context by building an ensemble of Hoeffding trees that are each limited to a small subset of attributes. In this way, each tree is restricted to model interactions between attributes in its corresponding subset. Because it is not known a priori which attribute subsets are relevant for prediction, we build exhaustive ensembles that consider all possible attribute subsets of a given size. As the resulting Hoeffding trees are not all equally important, we weigh them in a suitable manner to obtain accurate classifications. This is done by combining the log-odds of their probability estimates using sigmoid perceptrons, with one perceptron per class. We propose a mechanism for setting the perceptrons' learning rate using the ADWIN change detection method for data streams, and also use ADWIN to reset ensemble members (i.e., Hoeffding trees) when they no longer perform well. Our experiments show that the resulting ensemble classifier outperforms bagging for data streams in terms of accuracy when both are used in conjunction with adaptive naive Bayes Hoeffding trees, at the expense of runtime and memory consumption. We also show that our stacking method can improve the performance of a bagged ensemble.

year: 2012