title: Growth and magmatic evolution of Tongariro and Raupehu volcanoes, New Zealand

authors: Hobden, Barbara J.

abstract: The aim of this excursion is to examine new work on the eruptive and magmatic histories of Tongariro and Ruapehu Volcanoes. By integrating geochemical and isotopic analyses within a well-constrained framework of geochronology and volcanic stratigraphy, our studies have shown that growth of these andesite cone volcanoes involves multiple small batches of magma whose compositions are strongly modified in complex, probably polybaric plumbing systems on time scales as short as a year. Rapid production and ascent of magma is a characteristic of the Quaternary history of both the silicic and andesitic portions of Taupo Volcanic Zone (TVZ). Central TVZ is dominated by two exceptionally active rhyolitic calderas, Okataina and Taupo, while the landscape of the southem TVZ is dominated by two highly active composite volcanoes, Tonga1iro and Ruapehu. There are strong similarities between Tongariro and Ruapehu (compare for example Hobden et al., 1999 with Gamble et al., 1999).

text: Growth and magmatic evolution of Tongariro and Raupehu volcanoes, New Zealand The aim of this excursion is to examine new work on the eruptive and magmatic histories of Tongariro and Ruapehu Volcanoes. By integrating geochemical and isotopic analyses within a well-constrained framework of geochronology and volcanic stratigraphy, our studies have shown that growth of these andesite cone volcanoes involves multiple small batches of magma whose compositions are strongly modified in complex, probably polybaric plumbing systems on time scales as short as a year. Rapid production and ascent of magma is a characteristic of the Quaternary history of both the silicic and andesitic portions of Taupo Volcanic Zone (TVZ). Central TVZ is dominated by two exceptionally active rhyolitic calderas, Okataina and Taupo, while the landscape of the southem TVZ is dominated by two highly active composite volcanoes, Tonga1iro and Ruapehu. There are strong similarities between Tongariro and Ruapehu (compare for example Hobden et al., 1999 with Gamble et al., 1999).

year: 2001

title: Characteristics of temporal fluctuations in the hyperpolarized state of the cortical slow oscillation

authors: Wilson, Marcus T.

subjects: bioelectric potentials

abstract: We present evidence for the hypothesis that transitions between the low- and high-firing states of the cortical slow oscillation correspond to neuronal phase transitions. By analyzing intracellular recordings of the membrane potential during the cortical slow oscillation in rats, we quantify the temporal fluctuations in power and the frequency centroid of the power spectrum in the period of time before “down” to “up” transitions. By taking appropriate averages over such events, we present these statistics as a function of time before transition. The results demonstrate an increase in fluctuation power and time scale broadly consistent with the slowing of systems close to phase transitions. The analysis is complicated and limited by the difficulty in identifying when transitions begin, and removing dc trends in membrane potential.

text: Characteristics of temporal fluctuations in the hyperpolarized state of the cortical slow oscillation We present evidence for the hypothesis that transitions between the low- and high-firing states of the cortical slow oscillation correspond to neuronal phase transitions. By analyzing intracellular recordings of the membrane potential during the cortical slow oscillation in rats, we quantify the temporal fluctuations in power and the frequency centroid of the power spectrum in the period of time before “down” to “up” transitions. By taking appropriate averages over such events, we present these statistics as a function of time before transition. The results demonstrate an increase in fluctuation power and time scale broadly consistent with the slowing of systems close to phase transitions. The analysis is complicated and limited by the difficulty in identifying when transitions begin, and removing dc trends in membrane potential.

year: 2008

title: When loanwords are not lone words: Using networks and hypergraphs to explore Māori loanwords in New Zealand English

authors: Trye, David

abstract: Networks are being used to model an increasingly diverse range of realworld phenomena. This paper introduces an exploratory approach to studying loanwords in relation to one another, using networks of co-occurrence. While traditional studies treat individual loanwords as discrete items, we show that insights can be gained by focusing on the various loanwords that co-occur within each text in a corpus, especially when leveraging the notion of a hypergraph. Our research involves a case-study of New Zealand English (NZE), which borrows Indigenous Māori words on a large scale. We use a topic-constrained corpus to show that: (i) Māori loanword types tend not to occur by themselves in a text; (ii) infrequent loanwords are nearly always accompanied by frequent loanwords; and (iii) it is not uncommon for texts to contain a mixture of listed and unlisted loanwords, suggesting that NZE is still riding a wave of borrowing importation from Māori.

text: When loanwords are not lone words: Using networks and hypergraphs to explore Māori loanwords in New Zealand English Networks are being used to model an increasingly diverse range of realworld phenomena. This paper introduces an exploratory approach to studying loanwords in relation to one another, using networks of co-occurrence. While traditional studies treat individual loanwords as discrete items, we show that insights can be gained by focusing on the various loanwords that co-occur within each text in a corpus, especially when leveraging the notion of a hypergraph. Our research involves a case-study of New Zealand English (NZE), which borrows Indigenous Māori words on a large scale. We use a topic-constrained corpus to show that: (i) Māori loanword types tend not to occur by themselves in a text; (ii) infrequent loanwords are nearly always accompanied by frequent loanwords; and (iii) it is not uncommon for texts to contain a mixture of listed and unlisted loanwords, suggesting that NZE is still riding a wave of borrowing importation from Māori.

year: 2023