A semi-parametric approach to estimate risk functions associated with multi-dimensional exposure profiles: application to smoking and lung cancer

A common characteristic of environmental epidemiology is the multi-dimensional aspect of exposure patterns, frequently reduced to a cumulative exposure for simplicity of analysis. By adopting a flexible Bayesian clustering approach, we explore the risk function linking exposure history to disease. This approach is applied here to study the relationship between different smoking characteristics and lung cancer in the framework of a population based case control study

Variance matrix priors for Dirichlet process mixture models with Gaussian kernels

35 pagesThe Dirichlet Process Mixture Model (DPMM) is a Bayesian non-parametric approach widely used for density estimation and clustering. In this manuscript, we study the choice of prior for the variance or precision matrix when Gaussian kernels are adopted. Typically, in the relevant literature, the assessment of mixture models is done by considering observations in a space of only a handful of dimensions. Instead, we are concerned with more realistic problems of higher dimensionality, in a space of up to 20 dimensions. We observe that the choice of prior is increasingly important as the dimensionality of the problem increases. After identifying certain undesirable properties of standard priors in problems of higher dimensionality, we review and implement possible alternative priors. The most promising priors are identified, as well as other factors that affect the convergence of MCMC samplers. Our results show that the choice of prior is critical for deriving reliable posterior inferences. This manuscript offers a thorough overview and comparative investigation into possible priors, with detailed guidelines for their implementation. Although our work focuses on the use of the DPMM in clustering, it is also applicable to density estimation

Family experiences of living with an eating disorder: a narrative analysis

Families are considered important in the management and treatment of eating disorders. Yet, rarely has research focused on family experiences of living with an eating disorder. Addressing this gap, this study explores the experiences of an elite 21-year-old triathlete with an eating disorder in conjunction with the experiences of her parents. Family members attended interviews individually on three separate occasions over the course of a year. In line with the narrative approach adopted, whereby stories are considered the primary means to construct experience, interviews encouraged storytelling through an open-ended, participant-led structure. Narrative analysis involved repeated readings of the transcripts, sensitising towards issues of narrative content (key themes) and structure (overarching plot). Family difficulties arose when personal experiences strayed from culturally dominant narrative forms and when family members held contrasting narrative preferences. Suggestions are forwarded as to how an appreciation of eating disorder illness narratives might inform treatment and support

Disability and the gym: experiences, barriers and facilitators of gym use for individuals with physical disabilities

Purpose: Individuals with physical disabilities are among the most inactive population in society, arguably due to the lack of suitable environments to exercise. The gym is a space dedicated to improving physical fitness in a controlled environment with specialized equipment and qualified instructors. The feasibility of using this space to promote health to this population, however, is yet to be established. Method: Over an 18-month period, 21 people with physical disabilities were interviewed regarding their experiences in the gym. Data were collected using semi-structured interviews, transcribed verbatim, and subject to thematic analysis. Results: Four broad themes were identified: (1) experiencing enhanced well-ness, (2) perceived conflict between gym values and disability, (3) influence of a previous gym identity, and (4) experiences of psycho-emotional disablism. Conclusions: Participants were perceived to experience a variety of health benefits; however, they also experienced many barriers such as not aligning to the cultural norms of the gym, limited interpretations of health, oppressive messages from the built environment, and negative relational interactions. While there is potential for the gym to be used as a place to promote health, more must be done to foster an inclusive atmosphere in this space

Understanding physical activity participation in spinal cord injured populations: three narrative types for consideration

The aim of this study was to identity the types of physical activity narratives drawn upon by active spinal injured people. More than 50 h of semi-structured life-story interview data, collected as part of larger interdisciplinary program of disability lifestyle research, was analysed for 30 physically active male and female spinal cord injury (SCI) participants. A structural narrative analysis of data identified three narrative types which people with SCI draw on: (1) exercise is restitution, (2) exercise is medicine, and (3) exercise is progressive redemption. These insights contribute new knowledge by adding a unique narrative perspective to existing cognitive understanding of physical activity behaviour in the spinal cord injured population. The implications of this narrative typology for developing effective positive behavioural change interventions are critically discussed. It is concluded that the identified narratives types may be constitutive, as well as reflective, of physical activity experiences and therefore may be a useful tool on which to base physical activity promotion initiatives

Crossing boundaries: the perceived impact of disabled fitness instructors in the gym

Objectives For disabled individuals, the gym is perceived to be an inaccessible space to exercise due to the deeply embedded ableism within this environment. This study uniquely explored how disabled gym instructors perceived they impacted the gym environment and the possibilities of making the gym a more inclusive space for disabled people to exercise. Design We used an inductive, qualitative design whereby ten disabled gym instructors were purposefully sampled. Methods Data were rigorously collected through semi-structured interviews totalling 35 h, transcribed verbatim, and subject to thematic analysis. Results Participants perceived they made three key impacts in the gym. First, they believed they promoted the gym as a more inclusive environment through helping construct a more accessible physical space, embodying an alternate way of being and providing a relatable narrative. Second, instructors believed their own unique understanding of disability improved their capacity to relate to disabled gym clients by instilling a sense of camaraderie and acting as an aspirational future self. Third, participants felt they enhanced applied practice for training disabled clients through creativity in training and supporting non-disabled instructors. Conclusion This article makes a significant contribution to knowledge by highlighting that disabled gym instructors can play a vital role in promoting a more inclusive space to exercise. It also highlights that to increase gym use amongst disabled populations, efforts should consider the potential beneficial impacts of disabled gym instructors in relation to promoting health and well-being

Exercise is medicine? Most of the time for most; but not always for all

Based on extensive research on the relationship between exercise and health, exercise as a form of medicine is a powerful concept of growing popularity within healthcare, academia and policy. Proponents of this exercise is medicine (EiM) movement frame exercise as a panacea for a variety of health issues and uncritically promote exercise as good for all. Two clinical populations particularly influenced by the EiM agenda are spinal cord injury (SCI) and arthritis. The purpose of this research was to explore how individuals with SCI and arthritis personally make sense of their exercise experiences. Data were collected through semi-structured interviews with participants with SCI and 20 participants with arthritis. Following a thematic narrative analysis, three patterns were identified across the whole data set. These were: 1) exercise and restitution; 2) exercise and pain; and 3) exercise and pleasure. Taken together, these results provide new knowledge regarding the impact of exercise that both align with, and contrast, the dominant EiM discourse. When exercise is perceived as ‘medicine’, stories of exercise participation spoke of cure, and restitution, rather than health and well-being. Pain was an unwelcomed side effect of exercise participation for some, and had a detrimental impact upon motivation and engagement. Lastly, a focus upon the medicinal benefits of exercise did not reflect the multiple pleasures experienced through exercise participation. Thus, health professionals, academics and policy makers need to prescribe to more ethical forms of exercise promotion that may lead to more efficacious, person-sensitive interventions

The psychosocial impact of wheelchair tennis on participants from developing countries

Purpose: Individuals with physical disabilities in developing countries can experience many instances of psychosocial hardship. Although scholars have suggested that participation in sport can positively impact psychosocial health, few studies have explored this phenomenon within the disabled population of developing nations. Methods: Sixteen wheelchair tennis players were recruited across six developing countries and interviewed in regards to their experiences. Data were collected using semi-structured interviews, transcribed verbatim and subject to thematic analysis. Results: Wheelchair tennis players perceived their participation in sport enhanced their psychosocial well-being. Three broad themes emerged from analysis of the interviews; (1) developed transferrable skills, (2) perceived personal growth and (3) benefits of an athletic identity. Conclusions: Sports participation, in this case wheelchair tennis, may be a viable means to promote psychosocial well-being in disabled populations within developing nations. Moreover, sport holds the potential to challenge negative perceptions of disability at an individual and societal level within these cultures.Implication for RehabilitationIndividuals with physical disabilities in developing countries may experience psychosocial hardship and cultural stigma.Wheelchair sport may be a viable means to enhance psychosocial well-being in this population.Skills learnt “on court” are transferrable to everyday life potentially improving independence and quality of life.Identifying as an athlete can challenge negative cultural perceptions of disability

Processing of spatial-frequency altered faces in schizophrenia: Effects of illness phase and duration

Low spatial frequency (SF) processing has been shown to be impaired in people with schizophrenia, but it is not clear how this varies with clinical state or illness chronicity. We compared schizophrenia patients (SCZ, n534), first episode psychosis patients (FEP, n522), and healthy controls (CON, n535) on a gender/facial discrimination task. Images were either unaltered (broadband spatial frequency, BSF), or had high or low SF information removed (LSF and HSF conditions, respectively). The task was performed at hospital admission and discharge for patients, and at corresponding time points for controls. Groups were matched on visual acuity. At admission, compared to their BSF performance, each group was significantly worse with low SF stimuli, and most impaired with high SF stimuli. The level of impairment at each SF did not depend on group. At discharge, the SCZ group performed more poorly in the LSF condition than the other groups, and showed the greatest degree of performance decline collapsed over HSF and LSF conditions, although the latter finding was not significant when controlling for visual acuity. Performance did not change significantly over time for any group. HSF processing was strongly related to visual acuity at both time points for all groups. We conclude the following: 1) SF processing abilities in schizophrenia are relatively stable across clinical state; 2) face processing abnormalities in SCZ are not secondary to problems processing specific SFs, but are due to other known difficulties constructing visual representations from degraded information; and 3) the relationship between HSF processing and visual acuity, along with known SCZ- and medication-related acuity reductions, and the elimination of a SCZ-related impairment after controlling for visual acuity in this study, all raise the possibility that some prior findings of impaired perception in SCZ may be secondary to acuity reductions

A flexible framework for spatial capture-recapture with unknown identities

Funding: We acknowledge the funding support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the University of St Andrews. The fisher study was funded by InnoTech Alberta grants, Government of Alberta (Environment and Parks), The Beaver Hills Initiative, Alberta Conservation Association, NSERC, Royal Canadian Geographic Society, TD Friends of the Environment Foundation, and the Fur Institute of Canada scholarships.Camera traps or acoustic recorders are often used to sample wildlife populations. When animals can be individually identified, these data can be used with spatial capture-recapture (SCR) methods to assess populations. However, obtaining animal identities is often labor-intensive and not always possible for all detected animals. To address this problem, we formulate SCR, including acoustic SCR, as a marked Poisson process, comprising a single counting process for the detections of all animals and a mark distribution for what is observed (eg, animal identity, detector location). The counting process applies equally when it is animals appearing in front of camera traps and when vocalizations are captured by microphones, although the definition of a mark changes. When animals cannot be uniquely identified, the observed marks arise from a mixture of mark distributions defined by the animal activity centers and additional characteristics. Our method generalizes existing latent identity SCR models and provides an integrated framework that includes acoustic SCR. We apply our method to estimate density from a camera trap study of fisher (Pekania pennanti) and an acoustic survey of Cape Peninsula moss frog (Arthroleptella lightfooti). We also test it through simulation. We find latent identity SCR with additional marks such as sex or time of arrival to be a reliable method for estimating animal density.Peer reviewe