title: Development of an Intraruminal Controlled-Release Device

authors: McLellan, Bradley John

subjects: gas-producing cell

abstract: Slow-release devices retained in the rumen, are a simple method for continuous administration of bioactives to ruminant animals.  To satisfy regulatory requirements and avoid waste of bioactive due to under- or over-dosing, it is advantageous to have a constant and predictable release rate.  Existing intraruminal controlled-release technologies cannot easily be adapted for different bioactives or rates of release and can be influenced by the variable physiological environment in the rumen.  Some existing commercial products use the pressure generated by a hydrogen gas-producing cell to extrude fluids from a syringe-like device.  This technology may provide advantages for ruminal controlled-release as the gas production rate is unaffected by environment in the rumen and can be easily adjusted using electrical resistance applied to the gas cell.  This technology was adapted for use in the rumen in these studies.
Initial experiments identified the need for greater understanding of the rate that hydrogen is produced by the gas cell and the rate that gas diffuses through the barrel walls.  Gas production rate was found to be inversely proportional to the resistance applied to the gas-producing cell.  Factors affecting gas diffusion rate from the device were studied and a polymer was identified that reduced hydrogen diffusion to 5% of that for the initial components used.  A relationship was developed to predict the release profile of a device.  Controlled-release devices were constructed from selected materials.  They released blank formulation at in vitro at a constant rate, which was within experimental variation of predicted values.  Release rates from the devices used in vivo were slightly higher than predicted.  The presence of rumen gases inside in vivo devices suggested that the difference may be due to inward diffusion of these gases; these may be eliminated by further study of barrel materials.  Recommendations on the redesign of this technology for use as a generic intraruminal delivery system are given.

text: Development of an Intraruminal Controlled-Release Device Slow-release devices retained in the rumen, are a simple method for continuous administration of bioactives to ruminant animals.  To satisfy regulatory requirements and avoid waste of bioactive due to under- or over-dosing, it is advantageous to have a constant and predictable release rate.  Existing intraruminal controlled-release technologies cannot easily be adapted for different bioactives or rates of release and can be influenced by the variable physiological environment in the rumen.  Some existing commercial products use the pressure generated by a hydrogen gas-producing cell to extrude fluids from a syringe-like device.  This technology may provide advantages for ruminal controlled-release as the gas production rate is unaffected by environment in the rumen and can be easily adjusted using electrical resistance applied to the gas cell.  This technology was adapted for use in the rumen in these studies.
Initial experiments identified the need for greater understanding of the rate that hydrogen is produced by the gas cell and the rate that gas diffuses through the barrel walls.  Gas production rate was found to be inversely proportional to the resistance applied to the gas-producing cell.  Factors affecting gas diffusion rate from the device were studied and a polymer was identified that reduced hydrogen diffusion to 5% of that for the initial components used.  A relationship was developed to predict the release profile of a device.  Controlled-release devices were constructed from selected materials.  They released blank formulation at in vitro at a constant rate, which was within experimental variation of predicted values.  Release rates from the devices used in vivo were slightly higher than predicted.  The presence of rumen gases inside in vivo devices suggested that the difference may be due to inward diffusion of these gases; these may be eliminated by further study of barrel materials.  Recommendations on the redesign of this technology for use as a generic intraruminal delivery system are given.

year: 2007

title: The transition to parenthood in New Zealand and a developmental conceptual framework for the study of family change

authors: Swain, David

abstract: The research and reflection reported in this thesis was initially centred on parenthood as ‘crisis’ or ‘transition’. A prospective longitudinal survey of a representative or ‘normal’ cohort of 241 primiparae in Hamilton, New Zealand, was carried out. Data were collected by means of four structured interviews (two antenatal and two post-partum) based on largely pre-coded questionnaires. The Hobbs Checklist (Hobbs, 1965; 1968) was used to measure ‘crisis’. It was found that this New Zealand sample did not experience crisis at or around the birth of their first child. 
The originally-planned data analysis was a multivariate search for statistical predictors of ‘crisis’, together with an examination of the short- and medium-term consequences of that ‘crisis’. As a result of the finding of no crisis attention was refocussed on more conceptual, theoretical and epistemological issues. 
A conceptual framework or ‘model’ for handling developmental changes in families was devised. This framework brings together a variety of concepts and ideas from ‘the literature’ together with some original concepts and ideas developed in the course of this project. 
The conceptual framework is organised around four main dimensions of structure, interaction, transactions and norms. Attention is focussed on the transitions which families may be understood to make between family career categories, especially from ‘couple’ to ‘childbearing’ categories. Ideas of homeostasis, morphogenesis and conflict are integrated into the conceptual framework. 
The original dataset was then used to investigate the conceptual framework, and areas for both further conceptualisation and further empirical investigation were identified.
Some issues remaining from the earlier substantive literature were further considered. In particular, the question of whether a ‘crisis group’ is better understood as the researcher’s construct or a ‘real’ social grouping was considered. It was found to be the former. 
It is concluded that theoretical orientations and approaches to conceptualisation, as well as a concern with practical issues (social problems, parent education, social work etc.), have strongly influenced research on parenthood in the past towards a focus on ‘crisis’. It is argued that a more comprehensive conceptual framework for the study of developmental change in families is needed. A first draft of such a framework is offered, and the need for further conceptual, theoretical and empirical work is emphasised.

text: The transition to parenthood in New Zealand and a developmental conceptual framework for the study of family change The research and reflection reported in this thesis was initially centred on parenthood as ‘crisis’ or ‘transition’. A prospective longitudinal survey of a representative or ‘normal’ cohort of 241 primiparae in Hamilton, New Zealand, was carried out. Data were collected by means of four structured interviews (two antenatal and two post-partum) based on largely pre-coded questionnaires. The Hobbs Checklist (Hobbs, 1965; 1968) was used to measure ‘crisis’. It was found that this New Zealand sample did not experience crisis at or around the birth of their first child. 
The originally-planned data analysis was a multivariate search for statistical predictors of ‘crisis’, together with an examination of the short- and medium-term consequences of that ‘crisis’. As a result of the finding of no crisis attention was refocussed on more conceptual, theoretical and epistemological issues. 
A conceptual framework or ‘model’ for handling developmental changes in families was devised. This framework brings together a variety of concepts and ideas from ‘the literature’ together with some original concepts and ideas developed in the course of this project. 
The conceptual framework is organised around four main dimensions of structure, interaction, transactions and norms. Attention is focussed on the transitions which families may be understood to make between family career categories, especially from ‘couple’ to ‘childbearing’ categories. Ideas of homeostasis, morphogenesis and conflict are integrated into the conceptual framework. 
The original dataset was then used to investigate the conceptual framework, and areas for both further conceptualisation and further empirical investigation were identified.
Some issues remaining from the earlier substantive literature were further considered. In particular, the question of whether a ‘crisis group’ is better understood as the researcher’s construct or a ‘real’ social grouping was considered. It was found to be the former. 
It is concluded that theoretical orientations and approaches to conceptualisation, as well as a concern with practical issues (social problems, parent education, social work etc.), have strongly influenced research on parenthood in the past towards a focus on ‘crisis’. It is argued that a more comprehensive conceptual framework for the study of developmental change in families is needed. A first draft of such a framework is offered, and the need for further conceptual, theoretical and empirical work is emphasised.

year: 1985

title: Māori women and intimate partner violence: Some sociocultural influences

authors: Hoeata, Chloe

subjects: intimate partner violence

abstract: Intimate partner violence (IPV) has recently been acknowledged as a worldwide phenomenon, with approximately one in four intimate relationships containing some form of violence. This study explores the interaction between relationship dynamics, IPV and whānau and community influences. We completed narrative interviews with two Māori women in December 2010. Our findings confirm the results of earlier studies which have found that childhood experiences of violence, actual or witnessed, have a powerful effect that reverberate within adult lives and into the formation of intimate relationships. Our interviews show that Māori whānau and women are textured by the same patriarchal expectations that privilege men in the Pākehā world. We also found that seeking help from whānau to escape a violent relationship may not be the most welcomed course of action. We conclude with a discussion of future research directions.

text: Māori women and intimate partner violence: Some sociocultural influences Intimate partner violence (IPV) has recently been acknowledged as a worldwide phenomenon, with approximately one in four intimate relationships containing some form of violence. This study explores the interaction between relationship dynamics, IPV and whānau and community influences. We completed narrative interviews with two Māori women in December 2010. Our findings confirm the results of earlier studies which have found that childhood experiences of violence, actual or witnessed, have a powerful effect that reverberate within adult lives and into the formation of intimate relationships. Our interviews show that Māori whānau and women are textured by the same patriarchal expectations that privilege men in the Pākehā world. We also found that seeking help from whānau to escape a violent relationship may not be the most welcomed course of action. We conclude with a discussion of future research directions.

year: 2011