The physiological stress response to amputation in the eleven-armed sea star (Coscinasterias muricata) : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Zoology, Massey University, Palmerston North, New Zealand

The eleven-armed sea star, Coscinasterias muricata, is subject to human-induced stressors, such as invasive fishing activities, that can cause limb loss (amputation), and heavy metal discharge into their habitat. The well-being and survival of a keystone predator such as C. muricata has important ecological implications as their presence influences community structure in the marine environment. Understanding the stress physiology of an animal can provide insight into their overall health and survival. While the stress physiology of northern asteroid species (such as Asterias rubens) has been well documented, this has not been well studied with C. muricata. In this thesis, I was able to identify time-dependent changes in two physiological parameters (total coelomocyte count and dopamine levels in the coelomic fluid) in C. muricata subjected to amputation. There was a synchronous increase in both of these parameters 24 hours post amputation. Dopamine in the coelomic fluid was measured by using high performance liquid chromatography (HPLC). I adapted a pre-existing method involving pre-column derivatisation and fluorescent detection, which was initially developed for the detection of dopamine in porcine muscle. However, this method requires further development as it could not detect dopamine to the same sensitivity as previously reported HPLC methods using electrochemical detection. Lastly, the initial attempts at developing an in vitro cytotoxicity bioassay using C. muricata coelomocytes is described in detail. The initial aim of this experiment was to understand the effect of heavy metals on cellular parameters. However the experiment was hampered by unusually low cell counts in this species, which has not been previously reported. The knowledge gleaned from this study may provide the groundwork for future studies that use C. muricata coelomocytes for cytotoxicity testing or as a biomarker

Towards a Computational Model of Narrative on Social Media

This thesis describes a variety of approaches to developing a computational model of narrative on social media. Our goal is to use such a narrative model to identify efforts to manipulate public opinion on social media platforms like Twitter. We present a model in which narratives in a collection of tweets are represented as a graph. Elements from each tweet that are relevant to potential narratives are made into nodes in the graph; for this thesis, we populate graph nodes with tweets’ authors, hashtags, named entities (people, locations, organizations, etc.,), and moral foundations (central moral values framing the discussion). Two nodes are connected with an edge if the narrative elements they represent appear together in one or more tweets, with the edge weight corresponding to the number of tweets in which these elements coincide. We then explore multiple possible deep learning and graph analysis methods for identifying narratives in a collection of tweets, including clustering of language embeddings, topic modeling, community detection and random walks on our narrative graph, training a graph neural network to identify narratives in the graph, and training a graph embedding model to generate vector embeddings of graph nodes. While much work still remains to be done in this area, several of our techniques, especially the generation and clustering of graph embeddings, were able to identify groups of related and connected nodes that might form the beginnings of narratives. Further study of these or other techniques could allow for the reliable identification of full narratives and information operations on social media

Inference from randomized (factorial) experiments

This is a contribution to the discussion of the interesting paper by Ding [Statist. Sci. 32 (2017) 331–345], which contrasts approaches attributed to Neyman and Fisher. I believe that Fisher’s usual assumption was unit-treatment additivity, rather than the “sharp null hypothesis” attributed to him. Fisher also developed the notion of interaction in factorial experiments. His explanation leads directly to the concept of marginality, which is essential for the interpretation of data from any factorial experiment.Publisher PDFPeer reviewe

A V-grooved AlGaAs/GaAs passivated PN junction

A passivated, V-grooved GaAs solar cell offers important advantages in terms of improved optical coupling, higher short circuit current, and increased tolerance to particle radiation when compared to the planar cell configuration. An AlGaAs epilayer has been deposited on a p-type GaAs epilayer grown on an n-type V-grooved GaAs surface using MOCVD. A wet chemical etching process was used to produce a V-pattern with a 7.0 micron periodicity. Reflectivity measurements substantiate the expected decrease in solar reflectance. Scanning electron microscopy techniques were used to confirm the presence of the AlGaAs layer and verify the existence of a pn junction

The psychological wellbeing of women operating mining machinery in a fly-in fly-out capacity

The present study aimed to address the gap in the current mining research by investigating women’s experiences of working in the mining industry in a “bluecollar” work role and the impact of fly-in fly-out (FIFO) mining on their wellbeing. An Interpretative Phenomenological Approach (IPA) was used as a framework to explore the experiences of 19 female machine operators through in-depth interviewing at one mineral mine site in Queensland, Australia. IPA analysis revealed three themes as identified by the participants. The first theme described how workplace barriers to job progression were salient issues for the women, particularly in respect to discrimination from male supervisors and hematite restrictions unique to this mine. The second theme titled, suspension of short term living for long term gain resulted in women putting their home responsibilities and relationships on hold. However, women with children in the study were able to describe how they could manage their family and work responsibilities with the aid of a significant other. Adaptation to the lifestyle was the third theme and women were also able to utilise adaptation and coping mechanisms to manage the discrimination and obtain a sense of belonging. As a part of adapting to the FIFO lifestyle, the women spoke of the need for time out for solitude as a response to living and working in close proximity to colleagues and partners. Further research exploring women’s capacity to juggle child and family needs with FIFO is suggested