title: μ-Chart-based specification and refinement

authors: Goldson, Doug

subjects: computer science

abstract: We introduce two new notions of refinement for μ-charts and compare them with the existing notion due to Scholz. The two notions are interesting and important because one gives rise (via a logic) to a calculus for constructing refinements and the other gives rise (via model checking) to a way of checking that refinements hold. Thus we bring together the two competing worlds of model checking and proof.

text: μ-Chart-based specification and refinement We introduce two new notions of refinement for μ-charts and compare them with the existing notion due to Scholz. The two notions are interesting and important because one gives rise (via a logic) to a calculus for constructing refinements and the other gives rise (via model checking) to a way of checking that refinements hold. Thus we bring together the two competing worlds of model checking and proof.

year: 2002

title: Relationship between meteoric ¹⁰Be and NO₃⁻ concentrations in soils along Shackleton Glacier, Antarctica

authors: Diaz, Melisa A.

abstract: Outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced changes in ice thickness greater than other coastal regions of Antarctica during glacial maxima. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, complicating our understanding of ecological succession in TAM soils. Our knowledge of glacial extent on small spatial scales is limited for the TAM, and studies of soil exposure duration and disturbance, in particular, are rare. We collected surface soil samples and, in some places, depth profiles every 5 cm to refusal (up to 30 cm) from 11 ice-free areas along Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet. We explored the relationship between meteoric ¹⁰Be and NO₃⁻ in these soils as a tool for understanding landscape disturbance and wetting history and as exposure proxies. Concentrations of meteoric ¹⁰Be spanned more than an order of magnitude across the region (2.9×10⁸ to 73×10⁸ atoms g⁻¹) and are among the highest measured in polar regions. The concentrations of NO₃⁻ were similarly variable and ranged from ∼ μg g⁻¹ to 15 mg g⁻¹. In examining differences and similarities in the concentrations of ¹⁰Be and NO₃⁻ with depth, we suggest that much of the southern portion of the Shackleton Glacier region has likely developed under a hyper-arid climate regime with minimal disturbance. Finally, we inferred exposure time using ¹⁰Be concentrations. This analysis indicates that the soils we analyzed likely range from recent exposure (following the Last Glacial Maximum) to possibly >6 Myr. We suggest that further testing and interrogation of meteoric ¹⁰Be and NO₃⁻ concentrations and relationships in soils can provide important information regarding landscape development, soil evolution processes, and inferred exposure durations of surfaces in the TAM.

text: Relationship between meteoric ¹⁰Be and NO₃⁻ concentrations in soils along Shackleton Glacier, Antarctica Outlet glaciers that flow through the Transantarctic Mountains (TAM) experienced changes in ice thickness greater than other coastal regions of Antarctica during glacial maxima. As a result, ice-free areas that are currently exposed may have been covered by ice at various points during the Cenozoic, complicating our understanding of ecological succession in TAM soils. Our knowledge of glacial extent on small spatial scales is limited for the TAM, and studies of soil exposure duration and disturbance, in particular, are rare. We collected surface soil samples and, in some places, depth profiles every 5 cm to refusal (up to 30 cm) from 11 ice-free areas along Shackleton Glacier, a major outlet glacier of the East Antarctic Ice Sheet. We explored the relationship between meteoric ¹⁰Be and NO₃⁻ in these soils as a tool for understanding landscape disturbance and wetting history and as exposure proxies. Concentrations of meteoric ¹⁰Be spanned more than an order of magnitude across the region (2.9×10⁸ to 73×10⁸ atoms g⁻¹) and are among the highest measured in polar regions. The concentrations of NO₃⁻ were similarly variable and ranged from ∼ μg g⁻¹ to 15 mg g⁻¹. In examining differences and similarities in the concentrations of ¹⁰Be and NO₃⁻ with depth, we suggest that much of the southern portion of the Shackleton Glacier region has likely developed under a hyper-arid climate regime with minimal disturbance. Finally, we inferred exposure time using ¹⁰Be concentrations. This analysis indicates that the soils we analyzed likely range from recent exposure (following the Last Glacial Maximum) to possibly >6 Myr. We suggest that further testing and interrogation of meteoric ¹⁰Be and NO₃⁻ concentrations and relationships in soils can provide important information regarding landscape development, soil evolution processes, and inferred exposure durations of surfaces in the TAM.

year: 2021

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