title: Temperature Sensitivity of Soil Respiration

authors: Robinson, Jasmine May

subjects: Soil respiration

abstract: Biogeochemical cycles, such as the carbon (C) cycle, are being continuously affected by anthropogenic activities such as carbon dioxide (CO₂) release from fossil fuels and the decomposition of soil organic C following some land management practices. The C cycle consists of four C pools: atmospheric CO₂, biota (mostly in vegetation), the ocean and soil organic matter (SOM), this being the largest actively cycling C pool. Respiration is the main driver of CO₂ release into the atmosphere, and is extremely sensitive to changes in moisture and temperature with small changes in these variables having a major influence on C cycling. Studies have argued in favour of both positive and negative feedbacks between CO₂ and global warming, where increasing temperatures could either increase CO₂ production, or enhance C storage. These contradicting arguments about how temperature changes will affect C exchanges, makes the understanding of how temperature change will affect temperature sensitivity of the C cycle dynamics (including respiration) critical for C modelling and budgeting.
Studies have attempted to measure temperature sensitivity of respiration when trying to understand soil response variation in temperatures. However, synthesis of current literature highlighted that laboratory methods can be problematic and introduce artefacts that obscure true temperature sensitivity. Problems highlighted included, too few temperatures treatments at which respiration was measured, use of long-term incubations that do not control microbial adaptation, lack of seasonal measurements and accounting for variability in moisture content. 
A new laboratory method was developed for this thesis, which allowed for rapid determination of soil respiration rate at a wide range and number of temperatures to overcome some of the observed drawbacks frequently seen in the literature. A temperature block allowed simultaneous measurements of soil respiration rates over five hours at 44 different temperatures between ~4 and 50 °C. The objective of this thesis was to test this method on a variety of conditions (including different soil types, sampling season, range of moisture contents and pre-incubation temperatures) to understand how temperature sensitivity (Tm_sens) of soil respiration might change with different sample collection and processing approaches.
Seasonal measurements of respiration rates from different soil types collected from a single farm found a significant interaction for Tm_sens between soil type and season over the year. This interaction indicated that temperature sensitivity of soil respiration differed between soil types depending on season and thus in order to assess temperature sensitivity of soil respiration from a site, samples should be taken from all soil types at the location. Tm_sens was not dependent on season alone suggesting that a single sampling per year may be sufficient to estimate temperature sensitivity for a soil type, at least at a site with moderate changes in temperature during the year. Surprisingly, respiration rate response to temperature was not very sensitive to variations in soil moisture. Pre-incubated soils sampled for 10 months at different temperatures similarly resulted in no significant change in Tm_sens suggesting that temperature sensitivity of soil respiration can be accurately determined using soils stored at various temperatures and that microbial populations are relatively stable in response to incubation temperature. 
Overall the developed method was able to rapidly assess temperature sensitivity of several soils through time under a variety of treatments and suggested overall the microbial population did not change rapidly and retained its temperature sensitivity. The success of this method allows for future testing of other hypothesis with regard to temperature sensitivity of respiration.

text: Temperature Sensitivity of Soil Respiration Biogeochemical cycles, such as the carbon (C) cycle, are being continuously affected by anthropogenic activities such as carbon dioxide (CO₂) release from fossil fuels and the decomposition of soil organic C following some land management practices. The C cycle consists of four C pools: atmospheric CO₂, biota (mostly in vegetation), the ocean and soil organic matter (SOM), this being the largest actively cycling C pool. Respiration is the main driver of CO₂ release into the atmosphere, and is extremely sensitive to changes in moisture and temperature with small changes in these variables having a major influence on C cycling. Studies have argued in favour of both positive and negative feedbacks between CO₂ and global warming, where increasing temperatures could either increase CO₂ production, or enhance C storage. These contradicting arguments about how temperature changes will affect C exchanges, makes the understanding of how temperature change will affect temperature sensitivity of the C cycle dynamics (including respiration) critical for C modelling and budgeting.
Studies have attempted to measure temperature sensitivity of respiration when trying to understand soil response variation in temperatures. However, synthesis of current literature highlighted that laboratory methods can be problematic and introduce artefacts that obscure true temperature sensitivity. Problems highlighted included, too few temperatures treatments at which respiration was measured, use of long-term incubations that do not control microbial adaptation, lack of seasonal measurements and accounting for variability in moisture content. 
A new laboratory method was developed for this thesis, which allowed for rapid determination of soil respiration rate at a wide range and number of temperatures to overcome some of the observed drawbacks frequently seen in the literature. A temperature block allowed simultaneous measurements of soil respiration rates over five hours at 44 different temperatures between ~4 and 50 °C. The objective of this thesis was to test this method on a variety of conditions (including different soil types, sampling season, range of moisture contents and pre-incubation temperatures) to understand how temperature sensitivity (Tm_sens) of soil respiration might change with different sample collection and processing approaches.
Seasonal measurements of respiration rates from different soil types collected from a single farm found a significant interaction for Tm_sens between soil type and season over the year. This interaction indicated that temperature sensitivity of soil respiration differed between soil types depending on season and thus in order to assess temperature sensitivity of soil respiration from a site, samples should be taken from all soil types at the location. Tm_sens was not dependent on season alone suggesting that a single sampling per year may be sufficient to estimate temperature sensitivity for a soil type, at least at a site with moderate changes in temperature during the year. Surprisingly, respiration rate response to temperature was not very sensitive to variations in soil moisture. Pre-incubated soils sampled for 10 months at different temperatures similarly resulted in no significant change in Tm_sens suggesting that temperature sensitivity of soil respiration can be accurately determined using soils stored at various temperatures and that microbial populations are relatively stable in response to incubation temperature. 
Overall the developed method was able to rapidly assess temperature sensitivity of several soils through time under a variety of treatments and suggested overall the microbial population did not change rapidly and retained its temperature sensitivity. The success of this method allows for future testing of other hypothesis with regard to temperature sensitivity of respiration.

year: 2016

title: A passively adaptive screwdriver: a novel concept for controlling off-diagonal stiffness

authors: Ilanko, Sinniah

subjects: adaptive screwdriver

abstract: A concept for an automated screw driving mechanism is presented. The proposed mechanism has a self-adjusting axial stiffness that depends on the torsional resistance against screwing. It delivers a greater axial thrust when the torsional resistance is greater, for example, towards the final stage of a screwing operation.

text: A passively adaptive screwdriver: a novel concept for controlling off-diagonal stiffness A concept for an automated screw driving mechanism is presented. The proposed mechanism has a self-adjusting axial stiffness that depends on the torsional resistance against screwing. It delivers a greater axial thrust when the torsional resistance is greater, for example, towards the final stage of a screwing operation.

year: 2006

title: Institutional Racism and the Dynamics of Privilege in Public Health

authors: Came, Heather

subjects: Institutional racism

abstract: Institutional racism, a pattern of differential access to material resources and power determined by race, advantages one sector of the population while disadvantaging another. Such racism is not only about conspicuous acts of violence but can be carried in the hold of mono-cultural perspectives. Overt state violation of principles contributes to the backdrop against which much less overt yet insidious violations occur. New Zealand health policy is one such mono-cultural domain. It is dominated by western bio-medical discourses that preclude and under-value Māori,  the indigenous peoples of this land, in the conceptualisation, structure, content, and processes of health policies, despite Te Tiriti o Waitangi  guarantees to protect Māori interests.

Since the 1980s, the Department of Health has committed to honouring the Treaty of Waitangi as the founding document of Māori-settler relationships and governance arrangements. Subsequent Waitangi Tribunal reports, produced by an independent Commission of Inquiry have documented the often-illegal actions of successive governments advancing the interests of Pākehā  at the expense of Māori. Institutional controls have not prevented inequities between Māori and non-Māori across a plethora of social and economic indicators.

Activist scholars work to expose and transform perceived inequities. My research interest lies in how Crown Ministers and officials within the public health sector practice institutional racism and privilege and how it can be transformed. Through dialogue with Māori working within the health sector, fuelled by critical analysis and strategic advice from a research whānau (family) of Māori health leaders and a Pākehā Tiriti worker, and embracing the traditions of feminist and critical race theory  I provide evidence of racism that can invoke strong emotional reactions. More disturbing is its normalisation to nigh imperceptibility within ones personal and professional life. The exposure of racism as a socially created phenomenon is a strength of the research presented here. 

My action orientation is my ethical response. Honouring Te Tiriti o Waitangi is a pathway to transforming racism. Such change is likely to be resisted by the Pākehā majority. This anticipated resistance is not a credible reason to weaken responsibility for such necessary change. Transforming institutional racism needs to be driven by senior managers, professional bodies, unions, and by communities. Policies, practices and leadership that enable institutional racism need to be systematically eliminated from the health sector. Crown officials must be supported to strengthen their professional accountabilities and to embrace ethical bicultural practice. Greater transparency could enable more effective monitoring of Crown behaviour and support transformed practice.

text: Institutional Racism and the Dynamics of Privilege in Public Health Institutional racism, a pattern of differential access to material resources and power determined by race, advantages one sector of the population while disadvantaging another. Such racism is not only about conspicuous acts of violence but can be carried in the hold of mono-cultural perspectives. Overt state violation of principles contributes to the backdrop against which much less overt yet insidious violations occur. New Zealand health policy is one such mono-cultural domain. It is dominated by western bio-medical discourses that preclude and under-value Māori,  the indigenous peoples of this land, in the conceptualisation, structure, content, and processes of health policies, despite Te Tiriti o Waitangi  guarantees to protect Māori interests.

Since the 1980s, the Department of Health has committed to honouring the Treaty of Waitangi as the founding document of Māori-settler relationships and governance arrangements. Subsequent Waitangi Tribunal reports, produced by an independent Commission of Inquiry have documented the often-illegal actions of successive governments advancing the interests of Pākehā  at the expense of Māori. Institutional controls have not prevented inequities between Māori and non-Māori across a plethora of social and economic indicators.

Activist scholars work to expose and transform perceived inequities. My research interest lies in how Crown Ministers and officials within the public health sector practice institutional racism and privilege and how it can be transformed. Through dialogue with Māori working within the health sector, fuelled by critical analysis and strategic advice from a research whānau (family) of Māori health leaders and a Pākehā Tiriti worker, and embracing the traditions of feminist and critical race theory  I provide evidence of racism that can invoke strong emotional reactions. More disturbing is its normalisation to nigh imperceptibility within ones personal and professional life. The exposure of racism as a socially created phenomenon is a strength of the research presented here. 

My action orientation is my ethical response. Honouring Te Tiriti o Waitangi is a pathway to transforming racism. Such change is likely to be resisted by the Pākehā majority. This anticipated resistance is not a credible reason to weaken responsibility for such necessary change. Transforming institutional racism needs to be driven by senior managers, professional bodies, unions, and by communities. Policies, practices and leadership that enable institutional racism need to be systematically eliminated from the health sector. Crown officials must be supported to strengthen their professional accountabilities and to embrace ethical bicultural practice. Greater transparency could enable more effective monitoring of Crown behaviour and support transformed practice.

year: 2012