title: Enhanced sample preparation for quantitation of microcystins by matrix-assisted laser desorption/ionisation–time of flight mass spectrometry

authors: Puddick, Jonathan

subjects: MALDI–TOF mass spectrometry

abstract: Introduction: Microcystins (MCs) are a group of cyanotoxins which pose a serious health threat when present in aquatic systems. Quantitative analysis of MCs by matrix-assisted laser desorption/ionisation–time of flight (MALDI–TOF) mass spectrometry has potential for the processing of large numbers of samples quickly and economically. The existing method uses an expensive internal standard and protocols that are incompatible with automated sample preparation and data acquisition.
Objective: To produce a MALDI–TOF sample preparation technique for the quantitation of MCs that not only maintains reproducibility and sensitivity, but is also compatible with an automated work-flow.
Methodology: Seven different MALDI–TOF sample preparations were assessed for signal reproducibility (coefficient of variation) and sensitivity (method detection limit) using a cost-effective internal standard (angiotensin I). The best preparation was then assessed for its quantitative performance using three different MC congeners ([Dha7] MC-LR, MC-RR and MC-YR).
Results: The sensitivity of six of the preparations was acceptable, as was the reproducibility for two thin-layer preparations performed on a polished steel target. Both thin-layer preparations could be used with a MALDI-TOF mass spectrometer that automatically acquires data, and one could be used in an automated sample preparation work-flow. Further investigation using the thin-layer spot preparation demonstrated that linear quantification of three different MC congeners was possible.
Conclusion: The study demonstrates that with different sample preparation methods and modern instrumentation, large numbers of samples can be analysed rapidly for MCs at low cost.

text: Enhanced sample preparation for quantitation of microcystins by matrix-assisted laser desorption/ionisation–time of flight mass spectrometry Introduction: Microcystins (MCs) are a group of cyanotoxins which pose a serious health threat when present in aquatic systems. Quantitative analysis of MCs by matrix-assisted laser desorption/ionisation–time of flight (MALDI–TOF) mass spectrometry has potential for the processing of large numbers of samples quickly and economically. The existing method uses an expensive internal standard and protocols that are incompatible with automated sample preparation and data acquisition.
Objective: To produce a MALDI–TOF sample preparation technique for the quantitation of MCs that not only maintains reproducibility and sensitivity, but is also compatible with an automated work-flow.
Methodology: Seven different MALDI–TOF sample preparations were assessed for signal reproducibility (coefficient of variation) and sensitivity (method detection limit) using a cost-effective internal standard (angiotensin I). The best preparation was then assessed for its quantitative performance using three different MC congeners ([Dha7] MC-LR, MC-RR and MC-YR).
Results: The sensitivity of six of the preparations was acceptable, as was the reproducibility for two thin-layer preparations performed on a polished steel target. Both thin-layer preparations could be used with a MALDI-TOF mass spectrometer that automatically acquires data, and one could be used in an automated sample preparation work-flow. Further investigation using the thin-layer spot preparation demonstrated that linear quantification of three different MC congeners was possible.
Conclusion: The study demonstrates that with different sample preparation methods and modern instrumentation, large numbers of samples can be analysed rapidly for MCs at low cost.

year: 2011

title: How topography-dependent are topographic effects? Complementary numerical modeling of centrifuge experiments

authors: Jeong, Seokho

subjects: Science & Technology

abstract: Topographic effects, the modification of seismic shaking by irregular topographies compared to flat ground, have been extensively studied. Very few studies, however, have investigated the effects of the stratigraphy and nonlinear response of the underlying geology on topographic amplification. Furthermore, most experimental studies have been performed in the field, where it is often difficult to establish an ideal flat-ground reference station, as well as to characterize the soil properties and their spatial variability in sufficient detail. Dafni [1] recently tested the seismic response of step-like slopes in a series of centrifuge experiments, where the incident motion, reference station and material properties were characterized in detail. In this study, we investigated the influence of the container boundary on topographic effects observed in the centrifuge experiments by performing numerical simulations with and without the container boundary. Our analysis suggested that the rigid-body rocking motion of the centrifuge container likely increased the experimental topographic spectral ratios, contributing to the discrepancy between the simulated and observed spectral ratios. We also found that although the laminar box lateral boundaries caused spurious reflections, they didn’t qualitatively affect the ground surface amplification pattern compared to numerical predictions of the same configuration without boundaries. At the same time, and most importantly, however, we found that the baseplate –by trapping waves scattered and distracted by the slope– amplified the ground motion at the crest up to one order of magnitude compared to numerical predictions of the response in absence of the baseplate. Our results show that topographic effects can be significantly affected by the underlying soil stratigraphy; and allude to the potentially significant role of this phenomenon in elevating seismic risk in regions with strong topographic relief. The findings of this study also suggest that future studies will benefit from clear understanding and careful considerations of capabilities and limitations of different investigation methods and that the numerical modelling and the lab testing (or the field testing) methods should complement each other.

text: How topography-dependent are topographic effects? Complementary numerical modeling of centrifuge experiments Topographic effects, the modification of seismic shaking by irregular topographies compared to flat ground, have been extensively studied. Very few studies, however, have investigated the effects of the stratigraphy and nonlinear response of the underlying geology on topographic amplification. Furthermore, most experimental studies have been performed in the field, where it is often difficult to establish an ideal flat-ground reference station, as well as to characterize the soil properties and their spatial variability in sufficient detail. Dafni [1] recently tested the seismic response of step-like slopes in a series of centrifuge experiments, where the incident motion, reference station and material properties were characterized in detail. In this study, we investigated the influence of the container boundary on topographic effects observed in the centrifuge experiments by performing numerical simulations with and without the container boundary. Our analysis suggested that the rigid-body rocking motion of the centrifuge container likely increased the experimental topographic spectral ratios, contributing to the discrepancy between the simulated and observed spectral ratios. We also found that although the laminar box lateral boundaries caused spurious reflections, they didn’t qualitatively affect the ground surface amplification pattern compared to numerical predictions of the same configuration without boundaries. At the same time, and most importantly, however, we found that the baseplate –by trapping waves scattered and distracted by the slope– amplified the ground motion at the crest up to one order of magnitude compared to numerical predictions of the response in absence of the baseplate. Our results show that topographic effects can be significantly affected by the underlying soil stratigraphy; and allude to the potentially significant role of this phenomenon in elevating seismic risk in regions with strong topographic relief. The findings of this study also suggest that future studies will benefit from clear understanding and careful considerations of capabilities and limitations of different investigation methods and that the numerical modelling and the lab testing (or the field testing) methods should complement each other.

year: 2019

title: Health reform and the impact on Mäori 1983-1997

authors: Ferguson, Lisa Arleen.

abstract: This study investigates the New Zealand health sector reforms from 1983 to 1997and examines whether the reform process has been consistent with the principles of the Treaty of Waitangi. It evaluates the impact of the reforms on Mäori from that perspective. 

The study introduces the health sector reforms generally and then their specific effects on Mäori. It draws on two research exercises undertaken by the author, being research for the Wai 692 Napier Hospital and Health Services claim to the Waitangi Tribunal and on improving Mäori Health outcomes for the National Health Committee. The methodologies used are those from the discipline of history.

The study outlines the argument for Crown responsibilities under the Treaty and draws out the distinctions between Article 2 and Article 3 of the Treaty. It provides a historical background to the place of the Treaty in the health sector, and forms the basis for a Treaty based analysis of the health reforms and their impact. 

The New Zealand health sector has undergone massive government initiated structural change throughout the period under study. During this time the neo-liberal reforms have had a key role in reshaping health service structures. The process of change, the international influences on the changes, and the resulting entities are described. An example from Tainui Iwi of the effect of structural health reform illustrates the changes in Mäori health service provision by Mäori.
Since 1983 successive governments have produced copious Mäori health policy. The key policy documents, and their recommendations, are identified, as is the degree to which they were implemented. The cyclical nature of such policy making suggests that it is not always followed by policy implementation. While Mäori are identified as a health gain priority, the evidence reviewed shows that the responsibility to implement and monitor the policy is diffuse and ineffective.

The Wai 692 claim provides a detailed look at the impact of the 1990s health reform for Mäori. The claim was precipitated by the threatened closure of Napier Hospital, but was broadened to include a wide-ranging look at the impact of health reform on Mäori. As a case study it provides a specific example of one Iwi’s experience of the reality of policy implementation at that time versus policy making.

Crown evaluation of the effectiveness of its own policies, and the extent to which its own agencies breach those policies is explored. The lack of control and accountability measures, plus the inability of the Crown to monitor (let alone sanction) success or failure, is highlighted. A contrast is drawn between the health and local government sectors, using the operation of the Resource Management Act (1991). 

The latest health sector reforms consequent on the 1999 Labour/Alliance coalition government are briefly considered, together with an overview of the Crown’s effectiveness in delivering improved Mäori health outcomes. The study suggests that the use of the Treaty as a cornerstone for Maori health policy formation and delivery may lead to more effective engagement between the Crown and Mäori in addressing Mäori health issues. The study concludes by asking the question, has the health sector reform process of the 1980s and 1990s itself been a Treaty breach?

A brief postscript considers the further reform of the health sector beyond the period of study.

text: Health reform and the impact on Mäori 1983-1997 This study investigates the New Zealand health sector reforms from 1983 to 1997and examines whether the reform process has been consistent with the principles of the Treaty of Waitangi. It evaluates the impact of the reforms on Mäori from that perspective. 

The study introduces the health sector reforms generally and then their specific effects on Mäori. It draws on two research exercises undertaken by the author, being research for the Wai 692 Napier Hospital and Health Services claim to the Waitangi Tribunal and on improving Mäori Health outcomes for the National Health Committee. The methodologies used are those from the discipline of history.

The study outlines the argument for Crown responsibilities under the Treaty and draws out the distinctions between Article 2 and Article 3 of the Treaty. It provides a historical background to the place of the Treaty in the health sector, and forms the basis for a Treaty based analysis of the health reforms and their impact. 

The New Zealand health sector has undergone massive government initiated structural change throughout the period under study. During this time the neo-liberal reforms have had a key role in reshaping health service structures. The process of change, the international influences on the changes, and the resulting entities are described. An example from Tainui Iwi of the effect of structural health reform illustrates the changes in Mäori health service provision by Mäori.
Since 1983 successive governments have produced copious Mäori health policy. The key policy documents, and their recommendations, are identified, as is the degree to which they were implemented. The cyclical nature of such policy making suggests that it is not always followed by policy implementation. While Mäori are identified as a health gain priority, the evidence reviewed shows that the responsibility to implement and monitor the policy is diffuse and ineffective.

The Wai 692 claim provides a detailed look at the impact of the 1990s health reform for Mäori. The claim was precipitated by the threatened closure of Napier Hospital, but was broadened to include a wide-ranging look at the impact of health reform on Mäori. As a case study it provides a specific example of one Iwi’s experience of the reality of policy implementation at that time versus policy making.

Crown evaluation of the effectiveness of its own policies, and the extent to which its own agencies breach those policies is explored. The lack of control and accountability measures, plus the inability of the Crown to monitor (let alone sanction) success or failure, is highlighted. A contrast is drawn between the health and local government sectors, using the operation of the Resource Management Act (1991). 

The latest health sector reforms consequent on the 1999 Labour/Alliance coalition government are briefly considered, together with an overview of the Crown’s effectiveness in delivering improved Mäori health outcomes. The study suggests that the use of the Treaty as a cornerstone for Maori health policy formation and delivery may lead to more effective engagement between the Crown and Mäori in addressing Mäori health issues. The study concludes by asking the question, has the health sector reform process of the 1980s and 1990s itself been a Treaty breach?

A brief postscript considers the further reform of the health sector beyond the period of study.

year: 2002