title: Oxytocin as an appetite suppressant that reduces feeding reward

authors: Herisson, Florence

subjects: Oxytocin

abstract: In the environment in which palatable and highly caloric foods are readily available, eating behavior is oftentimes not dictated by the necessity to replenish lacking energy, but rather by the pleasure of consumption. Centrally acting oxytocin (OT) is known to promote termination of feeding to protect internal milieu by preventing excessive stomach distension, hyperosmolality and ingestion of toxins. Initial evidence suggests that another possible role for OT in mechanisms governing food intake is to reduce consumption of select palatable tastants. This thesis explores the question whether OT is as an appetite suppressant that reduces feeding reward. 
The first set of experiments addresses whether OT affects intake of (a) all carbohydrates, (b) only sweet carbohydrates or (c) sweet non-carbohydrate saccharin in mice. In those studies, generalized injection of a blood brain barrier penetrant OT receptor antagonist, L-368,899, significantly increased the intake of sweet (sucrose, glucose, fructose, polycose) and non-sweet (cornstarch) carbohydrates and promoted a trend approaching significance in saccharin consumption. Consumption of carbohydrate-enriched foods led to an increase in OT mRNA levels in the hypothalamus.
The second set of studies identifies the nucleus accumbens core (AcbC), a key component of the reward system, as a site that mediates anorexigenic effects of OT. Rats injected with OT directly in the AcbC showed a decreased intake of sucrose and saccharin solutions as well as of standard chow. This treatment did not cause taste aversion, hence the outcome was not due to sickness/malaise. The effects of AcbC OT on feeding could be observed only in animals offered a meal in a non-social environment. Once a social setting (devoid of direct antagonistic interactions between individuals) of a meal was introduced, AcbC OT failed to reduce feeding. AcbC levels of OT receptor transcript were affected by exposure to palatable food as well as by food deprivation.
The third and final set of studies shows that aberrant integrity of neuronal circuitry within the neuroendocrine and reward systems due to genetic deletion of connexin 36 (Cx36) gap junctions leads to dysregulation of the OT system’s functioning in the Cx36 KO mouse. This dysregulation is associated with hypersensitivity to aversive properties of foods, reduced interest in feeding for reward (palatable carbohydrates and saccharin) and abnormal ingestion of energy. 
Overall, the findings suggest that OT diminishes feeding for reward, particularly the intake of palatable carbohydrates and saccharin, by acting – at least in part – via the reward system. OT appears to be part of central mechanisms that cross-link homeostasis-driven and palatability-related (i.e., flavor- and macronutrient-specific) termination of consumption.

text: Oxytocin as an appetite suppressant that reduces feeding reward In the environment in which palatable and highly caloric foods are readily available, eating behavior is oftentimes not dictated by the necessity to replenish lacking energy, but rather by the pleasure of consumption. Centrally acting oxytocin (OT) is known to promote termination of feeding to protect internal milieu by preventing excessive stomach distension, hyperosmolality and ingestion of toxins. Initial evidence suggests that another possible role for OT in mechanisms governing food intake is to reduce consumption of select palatable tastants. This thesis explores the question whether OT is as an appetite suppressant that reduces feeding reward. 
The first set of experiments addresses whether OT affects intake of (a) all carbohydrates, (b) only sweet carbohydrates or (c) sweet non-carbohydrate saccharin in mice. In those studies, generalized injection of a blood brain barrier penetrant OT receptor antagonist, L-368,899, significantly increased the intake of sweet (sucrose, glucose, fructose, polycose) and non-sweet (cornstarch) carbohydrates and promoted a trend approaching significance in saccharin consumption. Consumption of carbohydrate-enriched foods led to an increase in OT mRNA levels in the hypothalamus.
The second set of studies identifies the nucleus accumbens core (AcbC), a key component of the reward system, as a site that mediates anorexigenic effects of OT. Rats injected with OT directly in the AcbC showed a decreased intake of sucrose and saccharin solutions as well as of standard chow. This treatment did not cause taste aversion, hence the outcome was not due to sickness/malaise. The effects of AcbC OT on feeding could be observed only in animals offered a meal in a non-social environment. Once a social setting (devoid of direct antagonistic interactions between individuals) of a meal was introduced, AcbC OT failed to reduce feeding. AcbC levels of OT receptor transcript were affected by exposure to palatable food as well as by food deprivation.
The third and final set of studies shows that aberrant integrity of neuronal circuitry within the neuroendocrine and reward systems due to genetic deletion of connexin 36 (Cx36) gap junctions leads to dysregulation of the OT system’s functioning in the Cx36 KO mouse. This dysregulation is associated with hypersensitivity to aversive properties of foods, reduced interest in feeding for reward (palatable carbohydrates and saccharin) and abnormal ingestion of energy. 
Overall, the findings suggest that OT diminishes feeding for reward, particularly the intake of palatable carbohydrates and saccharin, by acting – at least in part – via the reward system. OT appears to be part of central mechanisms that cross-link homeostasis-driven and palatability-related (i.e., flavor- and macronutrient-specific) termination of consumption.

year: 2016

title: An assessment of base load concentrating solar thermal power generation for New Zealand

authors: Anderson, Timothy Nicholas

abstract: With increasing pressure being placed on traditional energy sources, both in terms of supply and also regulatory, there is an increasing need to explore alternative generation technologies. In global terms, solar energy has the potential to make a significant contribution to worldwide energy demands in the future. This study examines recent developments in the emerging field of concentrating solar thermal power generation and explores the potential for base load electricity generation using this technology in New Zealand.

text: An assessment of base load concentrating solar thermal power generation for New Zealand With increasing pressure being placed on traditional energy sources, both in terms of supply and also regulatory, there is an increasing need to explore alternative generation technologies. In global terms, solar energy has the potential to make a significant contribution to worldwide energy demands in the future. This study examines recent developments in the emerging field of concentrating solar thermal power generation and explores the potential for base load electricity generation using this technology in New Zealand.

year: 2011

title: Volunteering at the edge of chaos: A case study on the self-organising of younger volunteers during the Rena oil spill crisis

authors: Lockwood, Sarah Jane

subjects: volunteer

abstract: This thesis investigates the self-organising of younger volunteers during the 2011 Rena oil spill crisis in Aotearoa/New Zealand. It builds on emerging research that considers the relationships between volunteering and activism and focuses on the ways in which younger volunteers carved out a ‘volunteer-activist’ space for themselves on the edge of the formal crisis responses.  
The research adopts a case study approach and uses an interpretive lens to investigate three research questions: (1) How was volunteering conceptualised by younger volunteers involved in the Rena crisis?; (2) How did the generational dynamics of younger volunteers affect the various organising responses to the Rena event?; and, (3) How was self-organising conceptualised by younger volunteers involved in the Rena crisis?
The data comprised interviews with 53 participants, 38 of whom were classified as younger volunteers (16-29 years of age) and 15 who held positions of authority in the Rena crisis response and who had high levels of engagement with the younger volunteers. By examining the intersections and overlaps of self-organising, younger generations of volunteers, and crisis events through a social constructionist methodology combined with an interpretive lens and reflexive position, the thesis makes several theoretical and practical contributions.
At a theoretical level, the thesis challenges traditional crisis management approaches dominated by command and control, formal, or top down organisational structures and arrangements. The thesis demonstrates how, as active members of society, younger volunteers developed alternate forms of participation to strengthen crisis response. 
Power tensions between younger volunteers and crisis officials were grounded in a deep sense of frustration resulting from negative societal views toward younger generational cohorts and the structural workings of a risk society. By reconciling social and institutional grievances through self-organising, younger volunteers could take advantage of their marginalised position and enact self-reflexive responses in ways that were not readily available to them in everyday life. This sense of empowerment helped younger volunteers navigate the structural uncertainties they faced as they transitioned towards a competitive labour market and also to take greater control of their lives during a crisis.
From an Aotearoa/New Zealand, perspective, the thesis also provides insights into how younger Māori participants made sense of and enacted their ‘volunteer’ experience and how this experience was influenced by culturally embedded principles. Importantly, there appeared to be no generational differences between how younger and older Māori participants made sense of their ‘volunteer’ experience. Both groups were driven by collectivist orientations, which highlights the importance of contextualising culture in volunteer sector research. 
The social constructedness of the media technologies used by participants exposed broader power structures that existed within their generation-specific social worlds. To this end, media multiplexity showed how use of different communication technologies (1) supported the maintenance of relationships between participants and (2) was fundamental to the meaning participants attached to the different forms of technologies. These findings indicate the need to move away from the current literature’s focus on the tools of communication technologies used by younger people during crisis events, towards the meanings that exist behind the use of such technologies as well as the digital relationships fostered among volunteers. 
This thesis contributes to the scholarship on volunteering and activism by showing how self-organising emerged as an alternative form of activist—or activator—approach to volunteer participation within a crisis response. This approach enabled young volunteer-activators to move beyond their perceived sense of marginalisation and avoid those formal organisational forces that limit their sense of freedom and personal development. The result was an alternative crisis response of self-organised volunteering on the edge of chaos.

text: Volunteering at the edge of chaos: A case study on the self-organising of younger volunteers during the Rena oil spill crisis This thesis investigates the self-organising of younger volunteers during the 2011 Rena oil spill crisis in Aotearoa/New Zealand. It builds on emerging research that considers the relationships between volunteering and activism and focuses on the ways in which younger volunteers carved out a ‘volunteer-activist’ space for themselves on the edge of the formal crisis responses.  
The research adopts a case study approach and uses an interpretive lens to investigate three research questions: (1) How was volunteering conceptualised by younger volunteers involved in the Rena crisis?; (2) How did the generational dynamics of younger volunteers affect the various organising responses to the Rena event?; and, (3) How was self-organising conceptualised by younger volunteers involved in the Rena crisis?
The data comprised interviews with 53 participants, 38 of whom were classified as younger volunteers (16-29 years of age) and 15 who held positions of authority in the Rena crisis response and who had high levels of engagement with the younger volunteers. By examining the intersections and overlaps of self-organising, younger generations of volunteers, and crisis events through a social constructionist methodology combined with an interpretive lens and reflexive position, the thesis makes several theoretical and practical contributions.
At a theoretical level, the thesis challenges traditional crisis management approaches dominated by command and control, formal, or top down organisational structures and arrangements. The thesis demonstrates how, as active members of society, younger volunteers developed alternate forms of participation to strengthen crisis response. 
Power tensions between younger volunteers and crisis officials were grounded in a deep sense of frustration resulting from negative societal views toward younger generational cohorts and the structural workings of a risk society. By reconciling social and institutional grievances through self-organising, younger volunteers could take advantage of their marginalised position and enact self-reflexive responses in ways that were not readily available to them in everyday life. This sense of empowerment helped younger volunteers navigate the structural uncertainties they faced as they transitioned towards a competitive labour market and also to take greater control of their lives during a crisis.
From an Aotearoa/New Zealand, perspective, the thesis also provides insights into how younger Māori participants made sense of and enacted their ‘volunteer’ experience and how this experience was influenced by culturally embedded principles. Importantly, there appeared to be no generational differences between how younger and older Māori participants made sense of their ‘volunteer’ experience. Both groups were driven by collectivist orientations, which highlights the importance of contextualising culture in volunteer sector research. 
The social constructedness of the media technologies used by participants exposed broader power structures that existed within their generation-specific social worlds. To this end, media multiplexity showed how use of different communication technologies (1) supported the maintenance of relationships between participants and (2) was fundamental to the meaning participants attached to the different forms of technologies. These findings indicate the need to move away from the current literature’s focus on the tools of communication technologies used by younger people during crisis events, towards the meanings that exist behind the use of such technologies as well as the digital relationships fostered among volunteers. 
This thesis contributes to the scholarship on volunteering and activism by showing how self-organising emerged as an alternative form of activist—or activator—approach to volunteer participation within a crisis response. This approach enabled young volunteer-activators to move beyond their perceived sense of marginalisation and avoid those formal organisational forces that limit their sense of freedom and personal development. The result was an alternative crisis response of self-organised volunteering on the edge of chaos.

year: 2019