title: Rapid time-domain simulation of fractional capacitors with SPICE

authors: Wilson, Marcus T.

abstract: Fractional capacitors, commonly called constant-phase elements or CPEs, are used in modeling and control applications, for example, for rechargeable batteries. Unfortunately, they are not natively supported in the well-used circuit simulator SPICE. This manuscript presents and demonstrates a modeling approach that allows users to incorporate these elements in circuits and model the response in the time domain. The novelty is that we implement for the first time a particular configuration of RC elements in parallel in a Foster-type network with SPICE in order to simulate a constant-phase element across a defined frequency range. We demonstrate that the circuit produces the required impedance spectrum in the frequency domain, and shows a power-law voltage response to a step change in current in the time domain, consistent with theory, and is able to reproduce the experimental voltage response to a complicated current profile in the time domain. The error depends on the chosen frequency limits and the number of RC branches, in addition to very small SPICE numerical errors. We are able to define an optimum circuit description that minimizes error while maintaining a short computation time. The scientific value is that the work permits rapid and accurate evaluation of the response of CPEs in the time domain, faster than other methods, using open source tools.

text: Rapid time-domain simulation of fractional capacitors with SPICE Fractional capacitors, commonly called constant-phase elements or CPEs, are used in modeling and control applications, for example, for rechargeable batteries. Unfortunately, they are not natively supported in the well-used circuit simulator SPICE. This manuscript presents and demonstrates a modeling approach that allows users to incorporate these elements in circuits and model the response in the time domain. The novelty is that we implement for the first time a particular configuration of RC elements in parallel in a Foster-type network with SPICE in order to simulate a constant-phase element across a defined frequency range. We demonstrate that the circuit produces the required impedance spectrum in the frequency domain, and shows a power-law voltage response to a step change in current in the time domain, consistent with theory, and is able to reproduce the experimental voltage response to a complicated current profile in the time domain. The error depends on the chosen frequency limits and the number of RC branches, in addition to very small SPICE numerical errors. We are able to define an optimum circuit description that minimizes error while maintaining a short computation time. The scientific value is that the work permits rapid and accurate evaluation of the response of CPEs in the time domain, faster than other methods, using open source tools.

year: 2024-01-01

title: “Not another patient through the revolving door”: A case study analysis of six women’s experiences with pregnancy terminations in New Zealand.

authors: Lee, Katherine Louise

subjects: Pregnancy termination

abstract: This thesis investigates an under-researched and largely ignored area in New Zealand, specifically six young women’s experiences of pregnancy termination in a New Zealand context. The aim of this research is twofold: to investigate the interconnection between intimate relationships and pregnancy terminations, and to describe and analyse the experiences of quality of care provided in New Zealand pregnancy termination settings. 

This research is conducted using a narrative methodology that allows each participant to have their own unique ‘voice’ and to offer valuable and rich insights into their personal experiences of pregnancy termination. Six participants were selected who met the criteria of being under 25 years of age at the time of their terminations. These participants were interviewed individually on three separate occasions using a qualitative semi-structured interview schedule with themes that included life before falling pregnant, culture and religion, intimate relationship pre- and post-termination, intimate relationship education (if any) provided at school, interaction with health professionals, accessibility, experiences on the day of the procedure, and participants’ advice for young women contemplating a termination. 

The findings from this thesis demonstrate a plethora of consequences for intimate relationships and the delivery of quality of care throughout the termination process. In terms of intimate relationships, the dissolution of the ‘honeymoon period’ exacerbated issues for women undergoing terminations. The quality of the relationship was found to be an important contributor to decision-making, particularly when the intimate partner was invited to share this responsibility. Problems arose in those relationships where there were incongruent experiences concerning the termination — for example, when one individual in the relationship was coping but the other was not. Irrespective of the quality of the relationship one key finding is that terminations appear to have a significant negative impact on future relationships. Interestingly, some participants chose to conceal their terminations from future intimate partners when then knew their partners were opposed to pregnancy terminations on ethical grounds. 

This thesis also highlights the considerable barriers to accessing termination clinics because they are located in the main centres and required most participants to travel to these clinics. Many participants struggled to ‘get a foot in the door’ and this often resulted in delayed entry to the service. Participants were aware of the role of the health professionals as the legal gatekeepers to the termination process and this led some to conceal their emotions, further heightening their stress on the day of the termination. The participants’ experiences of simply being a ‘number’ and part of the ‘revolving door’ process contributed towards their negative perceptions about, and experiences of, quality of care. The combination of their desire for but absence of tangibility, coupled with the non-alignment of participants’ expectations with the quality of care service they received, led some participants to have negative experiences of the termination process. 

The narratives that have been offered by the six young women who have had a termination provide valuable insights into, and reflections about, their personal experiences with a legal process that for many New Zealanders still remains ‘behind closed doors’.

text: “Not another patient through the revolving door”: A case study analysis of six women’s experiences with pregnancy terminations in New Zealand. This thesis investigates an under-researched and largely ignored area in New Zealand, specifically six young women’s experiences of pregnancy termination in a New Zealand context. The aim of this research is twofold: to investigate the interconnection between intimate relationships and pregnancy terminations, and to describe and analyse the experiences of quality of care provided in New Zealand pregnancy termination settings. 

This research is conducted using a narrative methodology that allows each participant to have their own unique ‘voice’ and to offer valuable and rich insights into their personal experiences of pregnancy termination. Six participants were selected who met the criteria of being under 25 years of age at the time of their terminations. These participants were interviewed individually on three separate occasions using a qualitative semi-structured interview schedule with themes that included life before falling pregnant, culture and religion, intimate relationship pre- and post-termination, intimate relationship education (if any) provided at school, interaction with health professionals, accessibility, experiences on the day of the procedure, and participants’ advice for young women contemplating a termination. 

The findings from this thesis demonstrate a plethora of consequences for intimate relationships and the delivery of quality of care throughout the termination process. In terms of intimate relationships, the dissolution of the ‘honeymoon period’ exacerbated issues for women undergoing terminations. The quality of the relationship was found to be an important contributor to decision-making, particularly when the intimate partner was invited to share this responsibility. Problems arose in those relationships where there were incongruent experiences concerning the termination — for example, when one individual in the relationship was coping but the other was not. Irrespective of the quality of the relationship one key finding is that terminations appear to have a significant negative impact on future relationships. Interestingly, some participants chose to conceal their terminations from future intimate partners when then knew their partners were opposed to pregnancy terminations on ethical grounds. 

This thesis also highlights the considerable barriers to accessing termination clinics because they are located in the main centres and required most participants to travel to these clinics. Many participants struggled to ‘get a foot in the door’ and this often resulted in delayed entry to the service. Participants were aware of the role of the health professionals as the legal gatekeepers to the termination process and this led some to conceal their emotions, further heightening their stress on the day of the termination. The participants’ experiences of simply being a ‘number’ and part of the ‘revolving door’ process contributed towards their negative perceptions about, and experiences of, quality of care. The combination of their desire for but absence of tangibility, coupled with the non-alignment of participants’ expectations with the quality of care service they received, led some participants to have negative experiences of the termination process. 

The narratives that have been offered by the six young women who have had a termination provide valuable insights into, and reflections about, their personal experiences with a legal process that for many New Zealanders still remains ‘behind closed doors’.

year: 2016

title: Tephras and New Zealand archaeology

authors: Lowe, David J.

subjects: tephrochronology

abstract: Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD  1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD  1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement.
The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

text: Tephras and New Zealand archaeology Establishing an accurate date for earliest Polynesian settlement in New Zealand is essential for understanding patterns of settlement and associated environmental impacts, and the processes and rates of cultural change in Eastern Polynesia. Tephra deposits from five volcanic centres, together with exotic sea-rafted pumice, provide isochronous constraints on the timing of earliest settlement and human impacts in northern New Zealand. A local basaltic tephra from Rangitoto Island (Auckland) and locally distributed andesitic tephras from Egmont volcano directly date human occupation to c. AD 1400–1450. Distal andesitic tephras (Tufa Trig Formation) from Mt Ruapehu, Tongariro volcanic centre, help constrain the timing of earliest anthropogenic deforestation signals in Hawke's Bay. Sea-rafted Loisels Pumice(s), although of uncertain stratigraphic reliability in places, overlies cultural remains that can be no younger than c. AD 1350 along the east coast, North Island. The regionally extensive rhyolitic Kaharoa Tephra, which erupted from Okataina volcano between c. AD  1300–1390, is the critical “settlement layer” datum for dating prehistory in the North Island: no human artefacts are recorded beneath it and the earliest inferred environmental impacts by humans are dated to c. AD  1280, just prior to its deposition. This maximum date matches the earliest radiocarbon dates derived for both settlement and human impacts from archaeological and natural sites (c. AD 1250), and implies that the onset of deforestation was essentially contemporaneous with initial settlement.
The widespread rhyolitic Taupo Tephra, which erupted from Taupo volcano c. AD 200, provides an isochronous benchmark well before earliest settlement. The tephra may coincide approximately with a putative earlier transient contact in New Zealand based on Pacific rat-bone (Rattus exulans) dates. More precise calendrical dates on the tephras—via dendrochronology or ice-core records or other dating methods—would help refine assessment of the timing of earliest settlement, while extending the distributional range of critical tephra layers, through application of crypto-tephra analysis, could lead to a greater understanding of settlement patterns.

year: 2000