title: Understanding the causes and consequences of variability in infant ERP editing practices.

authors: Monroy, Claire

subjects: ERP methodology

abstract: The current study examined the effects of variability on infant event-related potential (ERP) data editing methods. A widespread approach for analyzing infant ERPs is through a trial-by-trial editing process. Researchers identify electroencephalogram (EEG) channels containing artifacts and reject trials that are judged to contain excessive noise. This process can be performed manually by experienced researchers, partially automated by specialized software, or completely automated using an artifact-detection algorithm. Here, we compared the editing process from four different editors-three human experts and an automated algorithm-on the final ERP from an existing infant EEG dataset. Findings reveal that agreement between editors was low, for both the numbers of included trials and of interpolated channels. Critically, variability resulted in differences in the final ERP morphology and in the statistical results of the target ERP that each editor obtained. We also analyzed sources of disagreement by estimating the EEG characteristics that each human editor considered for accepting an ERP trial. In sum, our study reveals significant variability in ERP data editing pipelines, which has important consequences for the final ERP results. These findings represent an important step toward developing best practices for ERP editing methods in infancy research.

text: Understanding the causes and consequences of variability in infant ERP editing practices. The current study examined the effects of variability on infant event-related potential (ERP) data editing methods. A widespread approach for analyzing infant ERPs is through a trial-by-trial editing process. Researchers identify electroencephalogram (EEG) channels containing artifacts and reject trials that are judged to contain excessive noise. This process can be performed manually by experienced researchers, partially automated by specialized software, or completely automated using an artifact-detection algorithm. Here, we compared the editing process from four different editors-three human experts and an automated algorithm-on the final ERP from an existing infant EEG dataset. Findings reveal that agreement between editors was low, for both the numbers of included trials and of interpolated channels. Critically, variability resulted in differences in the final ERP morphology and in the statistical results of the target ERP that each editor obtained. We also analyzed sources of disagreement by estimating the EEG characteristics that each human editor considered for accepting an ERP trial. In sum, our study reveals significant variability in ERP data editing pipelines, which has important consequences for the final ERP results. These findings represent an important step toward developing best practices for ERP editing methods in infancy research.

year: 2021

title: Does the bipolar seesaw extend to the terrestrial southern mid-latitudes?

authors: Newnham, Rewi M.

subjects: bipolar seesaw

abstract: High precision comparison of Greenland and Antarctic ice cores, suggesting a pervasive antiphased temperature relationship between the polar hemispheres during the last glaciation, lends strong support to the bipolar seesaw model (EPICA, 2006). The extent to which reorganisation of ocean-heat transport during abrupt climate change events affected the southern mid-latitudes remains unclear, however, owing to a paucity of well-dated records with robust climate proxies, variability between some records, and varying interpretations of their significance. Here we present temperature reconstructions for three key pollen records recognised by the NZ-INTIMATE (NZ-I) group which, along with the preliminary NZ-I climate event stratigraphy (Alloway et al., 2007) and published marine records, are compared with polar ice core records for the interval 30–10 cal. ka. We focus on key events within the context of Dansgard Oeschger cycles 4–1 and The Antarctic Cold Reversal/Younger Dryas intervals. The New Zealand records are broadly consistent with an extended bipolar seesaw whereby the oceanic southern mid-latitudes are warmed at times of MOC weakening or cessation in the North Atlantic, and vice versa. Variability between records indicate that other factors must be involved, however, and nor do these records refute alternative models that predict an antiphased inter-hemispheric pattern. Nevertheless an extended bipolar model may explain an early onset of LGM conditions in New Zealand and elsewhere in the Southern Hemisphere at a time when interstadials GI3 and GI4 kept Greenland warm. Similar inter-hemispheric dynamics have been invoked to explain an earlier termination of the LGM in Antarctica than in Greenland (Wolff et al., 2009) which is also evident in the New Zealand records. A prominent mid-LGM interstadial complex observed in several New Zealand records, connected by tephrochronology may represent another antiphased event although stronger chronological control is needed to support this assertion. By comparison, the variability evident between New Zealand Lateglacial records cannot be explained simply by chronological imprecision and there may be latitudinal controls on the extent to which the Antarctic pattern is registered, as has been suggested from other records from the southern mid-high latitudes. Consolidation of these patterns is needed from more precise climate reconstructions at sites spread across latitudinal gradients in both the marine and terrestrial realms.

text: Does the bipolar seesaw extend to the terrestrial southern mid-latitudes? High precision comparison of Greenland and Antarctic ice cores, suggesting a pervasive antiphased temperature relationship between the polar hemispheres during the last glaciation, lends strong support to the bipolar seesaw model (EPICA, 2006). The extent to which reorganisation of ocean-heat transport during abrupt climate change events affected the southern mid-latitudes remains unclear, however, owing to a paucity of well-dated records with robust climate proxies, variability between some records, and varying interpretations of their significance. Here we present temperature reconstructions for three key pollen records recognised by the NZ-INTIMATE (NZ-I) group which, along with the preliminary NZ-I climate event stratigraphy (Alloway et al., 2007) and published marine records, are compared with polar ice core records for the interval 30–10 cal. ka. We focus on key events within the context of Dansgard Oeschger cycles 4–1 and The Antarctic Cold Reversal/Younger Dryas intervals. The New Zealand records are broadly consistent with an extended bipolar seesaw whereby the oceanic southern mid-latitudes are warmed at times of MOC weakening or cessation in the North Atlantic, and vice versa. Variability between records indicate that other factors must be involved, however, and nor do these records refute alternative models that predict an antiphased inter-hemispheric pattern. Nevertheless an extended bipolar model may explain an early onset of LGM conditions in New Zealand and elsewhere in the Southern Hemisphere at a time when interstadials GI3 and GI4 kept Greenland warm. Similar inter-hemispheric dynamics have been invoked to explain an earlier termination of the LGM in Antarctica than in Greenland (Wolff et al., 2009) which is also evident in the New Zealand records. A prominent mid-LGM interstadial complex observed in several New Zealand records, connected by tephrochronology may represent another antiphased event although stronger chronological control is needed to support this assertion. By comparison, the variability evident between New Zealand Lateglacial records cannot be explained simply by chronological imprecision and there may be latitudinal controls on the extent to which the Antarctic pattern is registered, as has been suggested from other records from the southern mid-high latitudes. Consolidation of these patterns is needed from more precise climate reconstructions at sites spread across latitudinal gradients in both the marine and terrestrial realms.

year: 2011

title: Poipoia te tamaiti ki te ūkaipō

authors: Gabel, Kirsten

abstract: This thesis explores traditional philosophies of Māori motherhood. Drawing from traditional accounts of our cosmologies, from mōteatea, whakatauki and pakiwaitara, it seeks to uncover aspects of our maternities that for many Māori mothers today have become buried under the plethora of Western maternal knowledges.
Māori maternities represent a conflicted space for Māori women and whānau in contemporary Aotearoa/New Zealand. Colonisation has acted to significantly corrupt a traditionally empowering and healthy philosophy of Māori motherhood. Successive legislative and social interventions have, over many generations, served to undermine the powerful position of the maternal in Māori society, to denigrate the sanctity of the Māori maternal body and to destroy a collective and supportive approach to raising children.
This thesis draws on Māori and indigenous legal theories, on mana wahine theories and on kaupapa Māori theories in its analysis. It unpacks some of the specific legislative and policy initiatives introduced by the state that have served to undermine traditional Māori maternities.
In the face of a comprehensive and targeted colonisation process, Māori maternities have survived and continue to be a site of resistance and empowerment for Māori whānau. Despite the best attempts of the state to undermine Māori maternities, Māori whānau have continued to mother in ways that reflect our traditional philosophies of mothering.
Finally, this thesis also proposes a theory of Māori motherhood that is grounded in our traditions, philosophies and ideologies. It concludes that Māori maternities are a significant space of resistance and tino rangatiratanga for Māori today.

text: Poipoia te tamaiti ki te ūkaipō This thesis explores traditional philosophies of Māori motherhood. Drawing from traditional accounts of our cosmologies, from mōteatea, whakatauki and pakiwaitara, it seeks to uncover aspects of our maternities that for many Māori mothers today have become buried under the plethora of Western maternal knowledges.
Māori maternities represent a conflicted space for Māori women and whānau in contemporary Aotearoa/New Zealand. Colonisation has acted to significantly corrupt a traditionally empowering and healthy philosophy of Māori motherhood. Successive legislative and social interventions have, over many generations, served to undermine the powerful position of the maternal in Māori society, to denigrate the sanctity of the Māori maternal body and to destroy a collective and supportive approach to raising children.
This thesis draws on Māori and indigenous legal theories, on mana wahine theories and on kaupapa Māori theories in its analysis. It unpacks some of the specific legislative and policy initiatives introduced by the state that have served to undermine traditional Māori maternities.
In the face of a comprehensive and targeted colonisation process, Māori maternities have survived and continue to be a site of resistance and empowerment for Māori whānau. Despite the best attempts of the state to undermine Māori maternities, Māori whānau have continued to mother in ways that reflect our traditional philosophies of mothering.
Finally, this thesis also proposes a theory of Māori motherhood that is grounded in our traditions, philosophies and ideologies. It concludes that Māori maternities are a significant space of resistance and tino rangatiratanga for Māori today.

year: 2013