Overfitting Bayesian mixture models with an unknown number of components

This paper proposes solutions to three issues pertaining to the estimation of finite mixture models with an unknown number of components: the non-identifiability induced by overfitting the number of components, the mixing limitations of standard Markov Chain Monte Carlo (MCMC) sampling techniques, and the related label switching problem. An overfitting approach is used to estimate the number of components in a finite mixture model via a Zmix algorithm. Zmix provides a bridge between multidimensional samplers and test based estimation methods, whereby priors are chosen to encourage extra groups to have weights approaching zero. MCMC sampling is made possible by the implementation of prior parallel tempering, an extension of parallel tempering. Zmix can accurately estimate the number of components, posterior parameter estimates and allocation probabilities given a sufficiently large sample size. The results will reflect uncertainty in the final model and will report the range of possible candidate models and their respective estimated probabilities from a single run. Label switching is resolved with a computationally light-weight method, Zswitch, developed for overfitted mixtures by exploiting the intuitiveness of allocation-based relabelling algorithms and the precision of label-invariant loss functions. Four simulation studies are included to illustrate Zmix and Zswitch, as well as three case studies from the literature. All methods are available as part of the R package Zmix, which can currently be applied to univariate Gaussian mixture models.

Growth and meaning from negotiating the complex journey of being an Emergency Medical Dispatcher

Emergency Medical Dispatchers (EMDs) are charged with taking the calls of those who ring the national emergency number for urgent medical assistance, for dispatching paramedical crews, and for providing as much assistance as can be offered remotely until paramedics arrive. In a job role which is filled with vicarious trauma, emergency situations, pressure, abuse, grief and loss, EMDs are often challenged in maintaining their mental health. The seemingly senseless death of a teenager who commits suicide, the devastating loss of a baby to Sudden Infant Death Syndrome, lives lost through natural disasters, and multiple vehicle fatalities are only a few of the types of experiences EMDs are faced with in the course of their work. However, amongst the horror are positive stories such as coaching a caller to negotiate the birth of a baby and saving a life in jeopardy from heart failure. EMD’s need to cope with the daily challenges of the role; make sense of their work and create meaning in order to have a fulfilled and sustainable career. Although some people in this work struggle greatly to withstand the impacts of vicarious trauma, there are also stories of personal growth. In this Chapter we use a case study to explore how meaning is made for those who are an auditory witness to a continual flux of trauma for others and how the traumatic experiences EMDs bear witness to can also be a catalyst for posttraumatic growth.

The use of a synthetic prostaglandin-E1 analog (misoprostol) as an adjunct to pancreatic-enzyme replacement in cystic-fibrosis

Eleven cystic fibrosis children (mean age, 9.6 years) were chosen at random to participate in a study to observe the effects of concurrently stimulating gastric/duodenal bicarbonate secretion and inhibiting gastric acid secretion, using a methylated prostaglandin E1 analogue in patients with pancreatic insufficiency and taking pancreatic enzymes. Percentage fat absorption in 3-day stool collections were calculated before and after commencing therapy with misoprostol, 400 μg/day in divided doses. We found a significant reduction in fat output (14.7 ± 11.7 versus 7.5 ± 3.5 g/day, p < 0.05) in the study group as a whole and a significant reduction in steatorrhoeic level as a percentage of fat intake in all of the patients with abnormal base-line collections (23.1% versus 9.2%, p < 0.002). We conclude that misoprostol should be considered in cystic fibrosis patients with steatorrhoea as a means of improving nutrient absorption.

J.W.Lindt’s Colonial man and Aborigine image from the GRAFTON ALBUM : “On chemistry and optics all does not depend, art must with these in triple union blend”

J.W.Lindt’s Colonial man and Aborigine image from the GRAFTON ALBUM: “On chemistry and optics all does not depend, art must with these in triple union blend” (text from J.W. Lindt’s photographic backing card) In this paper, I follow an argument that Lindt held a position in his particular colonial environment where he was simultaneously both an insider and an outsider and that such a position may be considered prerequisite in stimulating exchange. A study of the transition of J.W. Lindt in Grafton, N.S.W. in the 1860s from a traveller to a migrant and subsequently to a professional photographer, as well as Lindt’s photographic career, which evolved through strategic action and technical approaches to photography, bears witness to his cultural relativity. One untitled photograph from this period of work constructs a unique commentary of Australian colonial life that illustrates a non-hegemonic position, particularly as it was included in one of the first albums of photographs of Aborigines that Lindt gifted to an illustrious person (in this case the Mayor of Grafton). As in his other studio constructions, props and backdrops were arranged and sitters were positioned with care, but this photograph is the only one in the album that includes a non-Aborigine in a relationship to an Aborigine. An analysis of the props, technical details of the album and the image suggests a reconciliatory aspect that thwarts the predominant attitudes towards Aborigines in the area at that time.

Pull factors attracting residents to Finnish senior houses

Most elderly Finnish residents prefer to age in place, but some relocate because of push factors that create stress in their current homes and pull factors that attract them to a new dwelling. This survey examines the important pull factors that attract seniors to senior houses. Grocery nearby is the strongest pull factor followed by hospital or medical center and public transportation. A factor analysis reveals that attributes can be grouped into three factors: onsite services that allow the residents to maintain an active lifestyle with some luxury, everyday services and facilities that would enable aging in place, and physical activity facilities. Residents have chosen the type of senior housing that supports their lifestyle. Meanwhile, socioeconomic characteristics do not explain the differences in the types of features that attract residents.

Violence against the adolescents of Kolkata: A study in relation to the socio-economic background and mental health

This study attempts to understand the nature of violence suffered by the adolescents of Kolkata (erstwhile Calcutta) and to identify its relation with their socio-economic background and mental health variables such as anxiety, adjustment, and self-concept. It is a cross-sectional study covering a total of 370 adolescents (182 boys and 188 girls) from six higher secondary schools in Kolkata. The data was gathered by way of a semi-structured questionnaire and three standard psychological tests. Findings revealed that 52.4%, 25.1%, and 12.7% adolescents suffered psychological, physical, and sexual violence in the last year. Older adolescents (aged 17–18 years) suffered more psychological violence than the younger ones (15–16 years) (p < 0.05). Sixty nine (18.6%) adolescent students stood witness to violence between adult members in the family. More than three-fifth (61.9%) adolescents experienced at least one type of violence, while one-third (32.7%) experienced physical or sexual violence or both. Whatever its nature is, violence leaves a scar on the mental health of the victims. Those who have been through regular psychological violence reported high anxiety, emotional adjustment problem, and low self-concept. Sexual abuse left a damaging effect on self-concept (p < 0.05), while psychological violence or the witnessing of violence prompted high anxiety scores (p < 0.05), poor emotional adjustment (p < 0.05), and low self-concept (p < 0.05). This study stresses the need to provide individual counselling services to the maltreated adolescents of Kolkata so that their psychological traumas can heal and that they can move on in life with new hopes and dreams.

What are you doing?

Shot on locations in Sydney, Brisbane and at Screen Australia studios, this film surveys social inclusion strategies and seeks to influence the way school age young people interact with their peers with autism spectrum disorder. The film explores these interactions in a range of social environments ranging from classroom, playground and home-based settings. Following a brief cinema release in Australian capital cities, the film was packaged and made available for sale on DVD in Australia and North America. The film was chosen to be screened at the United Nations in New York to launch activities for World Autism Day in April 2013.

Equilibrium studies of ammonium exchange with Australian natural zeolites

This paper is concerned with the study of the equilibrium exchange of ammonium ions with two natural zeolite samples sourced in Australia from Castle Mountain Zeolites and Zeolite Australia. A range of sorption models including Langmuir Vageler, Competitive Langmuir, Freundlich, Temkin, Dubinin Astakhov and Brouers–Sotolongo were applied in order to gain an insight as to the exchange process. In contrast to most previous studies, non-linear regression was used in all instances to determine the best fit of the experimental data. Castle Mountain natural zeolite was found to exhibit higher ammonium capacity than Zeolite Australia material when in the freshly received state, and this behavior was related to the greater amount of sodium ions present relative to calcium ions on the zeolite exchange sites. The zeolite capacity for ammonium ions was also found to be dependent on the solution normality, with 35–60% increase inuptake noted when increasing the ammonium concentration from 250 to 1000 mg/L. The optimal fit ofthe equilibrium data was achieved by the Freundlich expression as confirmed by use of Akaikes Information Criteria. It was emphasized that the bottle-point method chosen influenced the isotherm profile in several ways, and could lead to misleading interpretation of experiments, especially if the constant zeolite mass approach was followed. Pre-treatment of natural zeolite with acid and subsequently sodium hydroxide promoted the uptake of ammonium species by at least 90%. This paper highlighted the factors which should be taken into account when investigating ammonium ion exchange with natural zeolites.

Applying the principles of interpretive field research: An example of an IS case study on shared services

All sound research commence with the selection of a research paradigm. The chosen research paradigm is significant in shaping the researcher’s perspectives of the world and it is a vital step in any study’s’ research design. There are different paradigms that IS researchers can choose from; amongst which the interpretive paradigm is growing in acceptance.. Though interpretive research has emerged as an important strand in Information Systems (IS), guidelines on how to conduct interpretive research and how to evaluate them have been scarce. Klein and Myers presented seven principles with examples for each from three case examples. While these principles are much valued, there is a lack of support for novice researchers on how to embed these principles in an overall research design, which could help with the aid of a detailed example that has done so. Thus, this paper aims to address this gap, and presents how Klein and Myers’s principles were applied within an example study that investigated shared services in the Malaysian Higher Education context. The example study adopted the interpretive paradigm as the most suited approach that fitted their research questions and goals. More details about the selection and adoption of the Klein and Myers’s guidelines in the context of the shared services research case study are presented in the paper.

Job-related diversity and team performance: An empirical analysis of the US music industry

A significant amount of research has been carried out to investigate the existing bonds between team characteristics and team outcomes in contexts of social creativity. Specifically, how work group diversity affects its performance is of great relevance but unfortunately, there is no clear understanding of the diversity-performance relationship. Therefore, to improve our understanding of this phenomenon, it would be worthwhile to investigate further empirical settings. For this reason, we decided to study the music industry that, to our knowledge, has never been chosen as empirical setting for the application of the theoretical constructs linked to the topic of team diversity and performance. Our research aims at analyze the US music industry to study the relationship between job-related characteristics of team diversity and team performances.

Fabrication and characterization of plasma polymer thin films from monoterpene alcohols for applications in organic electronics and biotechnology

After more than twenty years of basic and applied research, the use of nanotechnology in the design and manufacture of nanoscale materials is rapidly increasing, particularly in commercial applications that span from electronics across renewable energy areas, and biomedical devices. Novel polymers are attracting significant attention for they promise to provide a low−cost high−performance alternative to existing materials. Furthermore, these polymers have the potential to overcome limitations imposed by currently available materials thus enabling the development of new technologies and applications that are currently beyond our reach. This work focuses on the development of a range of new low−cost environmentally−friendly polymer materials for applications in areas of organic (flexible) electronics, optics, and biomaterials. The choice of the monomer reflects the environmentally−conscious focus of this project. Terpinen−4−ol is a major constituent of Australian grown Melaleuca alternifolia (tea tree) oil, attributed with the oil's antimicrobial and anti−inflammatory properties. Plasma polymerisation was chosen as a deposition technique for it requires minimal use of harmful chemicals and produces no hazardous by−products. Polymer thin films were fabricated under varied process conditions to attain materials with distinct physico−chemical, optoelectrical, biological and degradation characteristics. The resultant materials, named polyterpenol, were extensively characterised using a number of well−accepted and novel techniques, and their fundamental properties were defined. Polyterpenol films were demonstrated to be hydrocarbon rich, with variable content of oxygen moieties, primarily in the form of hydroxyl and carboxyl functionalities. The level of preservation of original monomer functionality was shown to be strongly dependent on the deposition energy, with higher applied power increasing the molecular fragmentation and substrate temperature. Polyterpenol water contact angle contact angle increased from 62.7° for the 10 W samples to 76.3° for the films deposited at 100 W. Polymers were determined to resist solubilisation by water, due to the extensive intermolecular and intramolecular hydrogen bonds present, and other solvents commonly employed in electronics and biomedical processing. Independent of deposition power, the surface topography of the polymers was shown to be smooth (Rq <0.5 nm), uniform and defect free. Hardness of polyterpenol coatings increased from 0.33 GPa for 10 W to 0.51 GPa for 100 W (at 500 μN load). Coatings deposited at higher input RF powers showed less mechanical deformation during nanoscratch testing, with no considerable damage, cracking or delamination observed. Independent of the substrate, the quality of film adhesion improved with RF power, suggesting these coatings are likely to be more stable and less susceptible to wear. Independent of fabrication conditions, polyterpenol thin films were optically transparent, with refractive index approximating that of glass. Refractive index increased slightly with deposition power, from 1.54 (10 W) to 1.56 (100 W) at 500 nm. The optical band gap values declined with increasing power, from 2.95 eV to 2.64 eV, placing the material within the range for semiconductors. Introduction of iodine impurity reduced the band gap of polyterpenol, from 2.8 eV to 1.64 eV, by extending the density of states more into the visible region of the electromagnetic spectrum. Doping decreased the transparency and increased the refractive index from 1.54 to 1.70 (at 500 nm). At optical frequencies, the real part of permittivity (k) was determined to be between 2.34 and 2.65, indicating a potential low-k material. These permittivity values were confirmed at microwave frequencies, where permittivity increased with input RF energy – from 2.32 to 2.53 (at 10 GHz ) and from 2.65 to 2.83 (at 20 GHz). At low frequencies, the dielectric constant was determined from current−voltage characteristics of Al−polyterpenol−Al devices. At frequencies below 100 kHz, the dielectric constant varied with RF power, from 3.86 to 4.42 at 1 kHz. For all samples, the resistivity was in order of 10⁸−10⁹ _m (at 6 V), confirming the insulating nature of polyterpenol material. In situ iodine doping was demonstrated to increase the conductivity of polyterpenol, from 5.05 × 10⁻⁸ S/cm to 1.20 × 10⁻⁶ S/cm (at 20 V). Exposed to ambient conditions over extended period of time, polyterpenol thin films were demonstrated to be optically, physically and chemically stable. The bulk of ageing occurred within first 150 h after deposition and was attributed to oxidation and volumetric relaxation. Thermal ageing studies indicated thermal stability increased for the films manufactured at higher RF powers, with degradation onset temperature associated with weight loss shifting from 150 ºC to 205 ºC for 10 W and 100 W polyterpenol, respectively. Annealing the films to 405 °C resulted in full dissociation of the polymer, with minimal residue. Given the outcomes of the fundamental characterisation, a number of potential applications for polyterpenol have been identified. Flexibility, tunable permittivity and loss tangent properties of polyterpenol suggest the material can be used as an insulating layer in plastic electronics. Implementation of polyterpenol as a surface modification of the gate insulator in pentacene-based Field Effect Transistor resulted in significant improvements, shifting the threshold voltage from + 20 V to –3 V, enhancing the effective mobility from 0.012 to 0.021 cm²/Vs, and improving the switching property of the device from 10⁷ to 10⁴. Polyterpenol was demonstrated to have a hole transport electron blocking property, with potential applications in many organic devices, such as organic light emitting diodes. Encapsulation of biomedical devices is also proposed, given that under favourable conditions, the original chemical and biological functionality of terpinen−4−ol molecule can be preserved. Films deposited at low RF power were shown to successfully prevent adhesion and retention of several important human pathogens, including P. aeruginosa, S. aureus, and S. epidermidis, whereas films deposited at higher RF power promoted bacterial cell adhesion and biofilm formation. Preliminary investigations into in vitro biocompatibility of polyterpenol demonstrated the coating to be non−toxic for several types of eukaryotic cells, including Balb/c mice macrophage and human monocyte type (HTP−1 non-adherent) cells. Applied to magnesium substrates, polyterpenol encapsulating layer significantly slowed down in vitro biodegradation of the metal, thus increasing the viability and growth of HTP−1 cells. Recently, applied to varied nanostructured titanium surfaces, polyterpenol thin films successfully reduced attachment, growth, and viability of P. aeruginosa and S. aureus.

Forgery attacks on ++AE authenticated encryption mode

In this paper, we analyse a block cipher mode of operation submitted in 2014 to the cryptographic competition for authenticated encryption (CAESAR). This mode is designed by Recacha and called ++AE (plus-plus-ae). We propose a chosen plaintext forgery attack on ++AE that requires only a single chosen message query to allow an attacker to construct multiple forged messages. Our attack is deterministic and guaranteed to pass ++AE integrity check. We demonstrate the forgery attack using 128-bit AES as the underlying block cipher. Hence, ++AE is insecure as an authenticated encryption mode of operation.

A role to play: Investigating concepts of masculinity in Australia through theatre

Health professionals, academics, social commentators and the media are increasingly sending the same message – Australian men are in crisis. This message has been supported by documented rises in alcoholism, violence, depression, suicide and crime amongst men in Australia. A major cause of this crisis, it can be argued, is an over-reliance on the out-dated and limited model of hegemonic masculinity that all men are encouraged to imitate in their own behaviour. This paper, as part of a larger study, explores representations of masculinity in selected works of contemporary Australian theatre in order to investigate the concept of hegemonic masculinity and any influence it may have on the perceived ‘crisis of masculinity’. Theatre is but one of the artistic modes that can be used to investigate masculinity and issues associated with identity. The Australia Council for the Arts recognises theatre, along with literature, dance, film, television, inter-arts, music and visual arts, as critical to the understanding and expression of Australian culture and identity. Theatre has been chosen in this instance because of the opportunities available to this study for direct access to specific theatre performances and creators and, also, because of the researcher’s experience, as a theatre director, with the dramatic arts. Through interviews with writers, directors and actors, combined with the analysis of scripts, academic writings, reviews, articles, programmes, play rehearsals and workshops, this research utilises theatre as a medium to explore masculinity in Australia.

(Re)presenting Masculinity: A theatre director's critical observations of, and theatrical experimentation with, (re)presentations of masculinity in selected works of contemporary Australian theatre

Health professionals, academics, social commentators and the media are increasingly sending the same message – Australian men are in crisis. This message has been supported by documented rises in alcoholism, violence, depression, suicide and crime amongst men in Australia. A major cause of this crisis, it can be argued, is an over-reliance on the out-dated and limited model of hegemonic masculinity that all men are encouraged to imitate in their own behaviour. This paper, as part of a larger study, explores representations of masculinity in selected works of contemporary Australian theatre in order to investigate the concept of hegemonic masculinity and any influence it may have on the perceived ‘crisis of masculinity’. Theatre is but one of the artistic modes that can be used to investigate masculinity and issues associated with identity. The Australia Council for the Arts recognises theatre, along with literature, dance, film, television, inter-arts, music and visual arts, as critical to the understanding and expression of Australian culture and identity. Theatre has been chosen in this instance because of the opportunities available to this study for direct access to specific theatre performances and creators and, also, because of the researcher’s experience, as a theatre director, with the dramatic arts. Through interviews with writers, directors and actors, combined with the analysis of scripts, academic writings, reviews, articles, programmes, play rehearsals and workshops, this research utilises theatre as a medium to explore masculinity in Australia.

Psychosocial presentation of revisional LAGB patients: A qualitative study

This qualitative study offers insight into the experiences, expectations, perceptions and beliefs that may lead to laparoscopic adjustable gastric band patients’ failure to achieve expected weight loss and seek revisional bariatric surgery. The 23 participants from two sites were interviewed and data were analysed from a grounded theory methodology in order to build a causal model. Analysis of participants’ reports identified ‘unrealistic expectations of the LAGB’ as the core category. Additionally, the restriction of the band had a negative impact on participants’ social interactions, leading to feelings of deprivation and, thus, to a desire for reward from food choices and consequently an increase of consumption of high-calorie-dense foods. These foods were chosen because of their specific texture or ability to provide reward. The resulting increase in weight or failure to achieve excess weight loss, led to feelings of shame and loneliness and emotional eating resulting in increased the consumption of rewarding foods. Thus, identifying unrealistic expectations of laparoscopic adjustable gastric band (LAGB) and emotional eating behaviours are important in those who are present initially for primary bariatric and revisional bariatric surgery, as they may contribute specifically to these patients’ weight regain and consequent failure to achieve excess weight loss.