title: Islands in the sand: are all hypolithic microbial communities the same?

authors: Lebre, Pedro H.

subjects: hypolithon

abstract: Hypolithic microbial communities (hypolithons) are complex assemblages of phototrophic and heterotrophic organisms associated with the ventral surfaces of translucent minerals embedded in soil surfaces. Past studies on the assembly, structure and function of hypolithic communities have tended to use composite samples (i.e. bulked hypolithic biomass) with the underlying assumption that samples collected from within a ‘homogeneous’ locality are phylogenetically homogeneous. In this study, we question this assumption by analysing the prokaryote phylogenetic diversity of multiple individual hypolithons: i.e. asking the seemingly simple question of ‘Are all hypolithons the same’? Using 16S rRNA gene-based phylogenetic analysis of hypolithons recovered for a localized moraine region in the Taylor Valley, McMurdo Dry Valleys, Antarctica, we demonstrate that these communities are heterogeneous at very small spatial scales (&amp;lt;5 m). Using null models of phylogenetic turnover, we showed that this heterogeneity between hypolithons is probably due to stochastic effects such as dispersal limitations, which is entirely consistent with the physically isolated nature of the hypolithic communities (‘islands in the sand’) and the almost complete absence of a liquid continuum as a mode of microbial transport between communities.

text: Islands in the sand: are all hypolithic microbial communities the same? Hypolithic microbial communities (hypolithons) are complex assemblages of phototrophic and heterotrophic organisms associated with the ventral surfaces of translucent minerals embedded in soil surfaces. Past studies on the assembly, structure and function of hypolithic communities have tended to use composite samples (i.e. bulked hypolithic biomass) with the underlying assumption that samples collected from within a ‘homogeneous’ locality are phylogenetically homogeneous. In this study, we question this assumption by analysing the prokaryote phylogenetic diversity of multiple individual hypolithons: i.e. asking the seemingly simple question of ‘Are all hypolithons the same’? Using 16S rRNA gene-based phylogenetic analysis of hypolithons recovered for a localized moraine region in the Taylor Valley, McMurdo Dry Valleys, Antarctica, we demonstrate that these communities are heterogeneous at very small spatial scales (&amp;lt;5 m). Using null models of phylogenetic turnover, we showed that this heterogeneity between hypolithons is probably due to stochastic effects such as dispersal limitations, which is entirely consistent with the physically isolated nature of the hypolithic communities (‘islands in the sand’) and the almost complete absence of a liquid continuum as a mode of microbial transport between communities.

year: 2021

title: Digital libraries and minority languages

authors: Nichols, David M.

subjects: computer science

abstract: Digital libraries have a pivotal role to play in the preservation and maintenance of international cultures in general and minority languages in particular. This paper outlines a software tool for building digital libraries that is well adapted for creating and distributing local information collections in minority languages, and describes some contexts in which it is used. The system can make multilingual documents available in structured collections and allows them to be accessed via multilingual interfaces. It is issued under a free open-source licence, which encourages participatory design of the software, and an end-user interface allows community-based localization of the various language interfaces - of which there are many.

text: Digital libraries and minority languages Digital libraries have a pivotal role to play in the preservation and maintenance of international cultures in general and minority languages in particular. This paper outlines a software tool for building digital libraries that is well adapted for creating and distributing local information collections in minority languages, and describes some contexts in which it is used. The system can make multilingual documents available in structured collections and allows them to be accessed via multilingual interfaces. It is issued under a free open-source licence, which encourages participatory design of the software, and an end-user interface allows community-based localization of the various language interfaces - of which there are many.

year: 2005

title: A cohort history of mortality in New Zealand

authors: Pool, Ian

abstract: This paper uses the generational life tables to track historical mortality experience for New Zealand Pakeha and Māori. The key research questions we seek to explore concern with why was Pakeha life expectation so high so early, and why did this survival advantage disappeared by the mid 20th century and what has happened since? For the Māori population what was the impact of contact on Māori mortality, what were the changes that have occurred and why, and what has happened to Māori mortality recently? A key finding from the cohort mortality analysis is that gains in survivorship have momentum effects that propel this advantage forward as survivors move up through the age-groups. That said, however, periods of gain may be followed later by cohort deterioration occurring among the same generations later in their life cycle, and even by further cycles of reprise and deterioration. These cycles of gain, deterioration, reprise etc are more evident for males, and particularly for Māori. Policy implications of these findings are discussed.

text: A cohort history of mortality in New Zealand This paper uses the generational life tables to track historical mortality experience for New Zealand Pakeha and Māori. The key research questions we seek to explore concern with why was Pakeha life expectation so high so early, and why did this survival advantage disappeared by the mid 20th century and what has happened since? For the Māori population what was the impact of contact on Māori mortality, what were the changes that have occurred and why, and what has happened to Māori mortality recently? A key finding from the cohort mortality analysis is that gains in survivorship have momentum effects that propel this advantage forward as survivors move up through the age-groups. That said, however, periods of gain may be followed later by cohort deterioration occurring among the same generations later in their life cycle, and even by further cycles of reprise and deterioration. These cycles of gain, deterioration, reprise etc are more evident for males, and particularly for Māori. Policy implications of these findings are discussed.

year: 2003