Propagation of low power low divergence Gaussian fields in unbiased self-defocusing photorefractive media and their interactions

Many optical networks are limited in speed and processing capability due to the necessity for the optical signal to be converted to an electrical signal and back again. In addition, electronically manipulated interconnects in an otherwise optical network lead to overly complicated systems. Optical spatial solitons are optical beams that propagate without spatial divergence. They are capable of phase dependent interactions, and have therefore been extensively researched as suitable all optical interconnects for over 20 years. However, they require additional external components, initially high voltage power sources were required, several years later, high power background illumination had replaced the high voltage. However, these additional components have always remained as the greatest hurdle in realising the applications of the interactions of spatial optical solitons as all optical interconnects. Recently however, self-focusing was observed in an otherwise self-defocusing photorefractive crystal. This observation raises the possibility of the formation of soliton-like fields in unbiased self-defocusing media, without the need for an applied electrical field or background illumination. This thesis will present an examination of the possibility of the formation of soliton-like low divergence fields in unbiased self-defocusing photorefractive media. The optimal incident beam and photorefractive media parameters for the formation of these fields will be presented, together with an analytical and numerical study of the effect of these parameters. In addition, preliminary examination of the interactions of two of these fields will be presented. In order to complete an analytical examination of the field propagating through the photorefractive medium, the spatial profile of the beam after propagation through the medium was determined. For a low power solution, it was found that an incident Gaussian field maintains its Gaussian profile as it propagates. This allowed the beam at all times to be described by an individual complex beam parameter, while also allowing simple analytical solutions to the appropriate wave equation. An analytical model was developed to describe the effect of the photorefractive medium on the Gaussian beam. Using this model, expressions for the required intensity dependent change in both the real and imaginary components of the refractive index were found. Numerical investigation showed that under certain conditions, a low powered Gaussian field could propagate in self-defocusing photorefractive media with divergence of approximately 0.1 % per metre. An investigation into the parameters of a Ce:BaTiO3 crystal showed that the intensity dependent absorption is wavelength dependent, and can in fact transition to intensity dependent transparency. Thus, with careful wavelength selection, the required intensity dependent change in both the real and imaginary components of the refractive index for the formation of a low divergence Gaussian field are physically realisable. A theoretical model incorporating the dependence of the change in real and imaginary components of the refractive index on propagation distance was developed. Analytical and numerical results from this model are congruent with the results from the previous model, showing low divergence fields with divergence less than 0.003 % over the propagation length of the photorefractive medium. In addition, this approach also confirmed the previously mentioned self-focusing effect of the self-defocusing media, and provided an analogy to a negative index GRIN lens with an intensity dependent focal length. Experimental results supported the findings of the numerical analysis. Two low divergence fields were found to possess the ability to interact in a Ce:BaTiO3 crystal in a soliton-like fashion. The strength of these interactions was found to be dependent on the degree of divergence of the individual beams. This research found that low-divergence fields are possible in unbiased self-defocusing photorefractive media, and that soliton-like interactions between two of these fields are possible. However, in order for these types of fields to be used in future all optical interconnects, the manipulation of these interactions, together with the ability for these fields to guide a second beam at a different wavelength, must be investigated.

Gimmelife : listening for dialogic voices in the email self-narratives of gifted young adolescents

The art of listening for voices within narrative research is a positive endeavour that has specific value within research design and subsequent approaches to analysis. This paper details an investigation into the dialogic nature of voices among gifted young adolescents who engaged in the co-construction of email-generated self-narratives. Data are drawn from a study involving ten adolescents, aged between ten and fourteen years, diagnosed as gifted according to Australian guidelines. Individual participants were asked to produce self-managed journal entries written and sent as asynchronous emails to the researcher who was the sole recipient and respondent. Within this approach, specific techniques of listening were used to examine a series of multi-vocal narratives generated over a period of six months. This paper proposes that an adaptation of the everyday convenience of email with the traditional journal format as a self-report mechanism creates a synergy that fosters self-disclosure. Individual excerpts are presented to show that the harnessing of personal narratives within an email context has potential to yield valuable insights into the emotions, personal realities and experiences of gifted young adolescents. Furthermore, the co-construction of self-expressive and explanatory narratives supported by a facilitative adult listener appeared to promote healthy self-awareness amongst participants. This paper contributes to narrative exploration in two distinct ways: first, in using online methods for gaining access to the everyday, emotional realities of participants; and, second, in demonstrating the value of listening as a narrative technique for uncovering layers of voices across a body of texts produced over time. These methods represent an innovative attempt to move beyond face-to-face approaches and away from a focus on content and coding techniques that might oversimplify complex emotions.

The Drinking Expectancy Questionnaire for Men who have Sex with Men (DEQ-MSM): A measure of substance-related beliefs

Introduction and Aims. Alcohol expectancies are associated with drinking behaviour and post-drinking use thoughts, feelings and behaviours. The expectancies held by specific cultural or sub-cultural groups have rarely been investigated. This research maps expectancies specific to gay and other men who have sex with men (MSM) and their relationship with substance use. This study describes the specific development of a measure of such beliefs for alcohol, the Drinking Expectancy Questionnaire for Men who have Sex with Men (DEQ-MSM). Design and Methods. Items selected through a focus group and interviews were piloted on 220 self-identified gay or other MSM via an online questionnaire. Results. Factor analysis revealed three distinct substance reinforcement domains ('Cognitive impairment', 'Sexual activity' and 'Social and emotional facilitation'). These factors were associated with consumption patterns of alcohol, and in a crucial test of discriminant validity were not associated with the consumption of cannabis or stimulants. Similarities and differences with existing measures will also be discussed. Discussion and Conclusions. The DEQ-MSM represents a reliable and valid measure of outcome expectancies, related to alcohol use among MSM, and represents an important advance as no known existing alcohol expectancy measure, to date, has been developed and/or normed for use among this group. Future applications of the DEQ-MSM in health promotion, clinical settings and research may contribute to reducing harm associated with alcohol use among MSM, including the development of alcohol use among young gay men.

Determinants of skin self-examination (SSE) in men aged 50 years or older

Background: Queensland men aged 50 years and older are at high risk for melanoma. Early detection via skin self examination (SSE) (particularly whole-body SSE) followed by presentation to a doctor with suspicious lesions, may decrease morbidity and mortality from melanoma. Prevalence of whole-body SSE (wbSSE) is lower in Queensland older men compared to other population subgroups. With the exception of the present study no previous research has investigated the determinants of wbSSE in older men, or interventions to increase the behaviour in this population. Furthermore, although past SSE intervention studies for other populations have cited health behaviour models in the development of interventions, no study has tested these models in full. The Skin Awareness Study: A recent randomised trial, called the Skin Awareness Study, tested the impact of a video-delivered intervention compared to written materials alone on wbSSE in men aged 50 years or older (n=930). Men were recruited from the general population and interviewed over the telephone at baseline and 13 months. The proportion of men who reported wbSSE rose from 10% to 31% in the control group, and from 11% to 36% in the intervention group. Current research: The current research was a secondary analysis of data collected for the Skin Awareness Study. The objectives were as follows: • To describe how men who did not take up any SSE during the study period differed from those who did take up examining their skin. • To determine whether the intervention program was successful in affecting the constructs of the Health Belief Model it was aimed at (self-efficacy, perceived threat, and outcome expectations); and whether this in turn influenced wbSSE. • To determine whether the Health Action Process Approach (HAPA) was a better predictor of wbSSE behaviour compared to the Health Belief Model (HBM). Methods: For objective 1, men who did not report any past SSE at baseline (n=308) were categorised as having ‘taken up SSE’ (reported SSE at study end) or ‘resisted SSE’ (reported no SSE at study end). Bivariate logistic regression, followed by multivariable regression, investigated the association between participant characteristics measured at baseline and resisting SSE. For objective 2 proxy measures of self-efficacy, perceived threat, and outcome expectations were selected. To determine whether these mediated the effect of the intervention on the outcome, a mediator analysis was performed with all participants who completed interviews at both time points (n=830) following the Baron and Kenny approach, modified for use with structural equation modelling (SEM). For objective 3, control group participants only were included (n=410). Proxy measures of all HBM and HAPA constructs were selected and SEM was used to build up models and test the significance of each hypothesised pathway. A likelihood ratio test compared the HAPA to the HBM. Results: Amongst men who did not report any SSE at baseline, 27% did not take up any SSE by the end of the study. In multivariable analyses, resisting SSE was associated with having more freckly skin (p=0.027); being unsure about the statement ‘if I saw something suspicious on my skin, I’d go to the doctor straight away’ (p=0.028); not intending to perform SSE (p=0.015), having lower SSE self-efficacy (p<0.001), and having no recommendation for SSE from a doctor (p=0.002). In the mediator analysis none of the tested variables mediated the relationship between the intervention and wbSSE. In regards to health behaviour models, the HBM did not predict wbSSE well overall. Only the construct of self-efficacy was a significant predictor of future wbSSE (p=0.001), while neither perceived threat (p=0.584) nor outcome expectations (p=0.220) were. By contrast, when the HAPA constructs were added, all three HBM variables predicted intention to perform SSE, which in turn predicted future behaviour (p=0.015). The HAPA construct of volitional self-efficacy was also associated with wbSSE (p=0.046). The HAPA was a significantly better model compared to the HBM (p<0.001). Limitations: Items selected to measure HBM and HAPA model constructs for objectives 2 and 3 may not have accurately reflected each construct. Conclusions: This research added to the evidence base on how best to target interventions to older men; and on the appropriateness of particular health behaviour models to guide interventions. Findings indicate that to overcome resistance those men with more negative pre-existing attitudes to SSE (not intending to do it, lower initial self-efficacy) may need to be targeted with more intensive interventions in the future. Involving general practitioners in recommending SSE to their patients in this population, alongside disseminating an intervention, may increase its success. Comparison of the HBM and HAPA showed that while two of the three HBM variables examined did not directly predict future wbSSE, all three were associated with intention to self-examine skin. This suggests that in this population, intervening on these variables may increase intention to examine skin, but not necessarily the behaviour itself. Future interventions could potentially focus on increasing both the motivational variables of perceived threat and outcome expectations as well as a combination of both action and volitional self-efficacy; with the aim of increasing intention as well as its translation to taking up and maintaining regular wbSSE.

Combining influence maps and cellular automata for reactive game agents

Agents make up an important part of game worlds, ranging from the characters and monsters that live in the world to the armies that the player controls. Despite their importance, agents in current games rarely display an awareness of their environment or react appropriately, which severely detracts from the believability of the game. Some games have included agents with a basic awareness of other agents, but they are still unaware of important game events or environmental conditions. This paper presents an agent design we have developed, which combines cellular automata for environmental modeling with influence maps for agent decision-making. The agents were implemented into a 3D game environment we have developed, the EmerGEnT system, and tuned through three experiments. The result is simple, flexible game agents that are able to respond to natural phenomena (e.g. rain or fire), while pursuing a goal.

Caseload management, work-related stress and case manager self-efficacy among Victorian mental health case managers

Objective: In Australia and comparable countries, case management has become the dominant process by which public mental health services provide outpatient clinical services to people with severe mental illness. There is recognition that caseload size impacts on service provision and that management of caseloads is an important dimension of overall service management. There has been little empirical investigation, however, of caseload and its management. The present study was undertaken in the context of an industrial agreement in Victoria, Australia that required services to introduce standardized approaches to caseload management. The aims of the present study were therefore to (i) investigate caseload size and approaches to caseload management in Victoria's mental health services; and (ii) determine whether caseload size and/or approach to caseload management is associated with work-related stress or case manager self-efficacy among community mental health professionals employed in Victoria's mental health services. Method: A total of 188 case managers responded to an online cross-sectional survey with both purpose-developed items investigating methods of case allocation and caseload monitoring, and standard measures of work-related stress and case manager personal efficacy. Results: The mean caseload size was 20 per full-time case manager. Both work-related stress scores and case manager personal efficacy scores were broadly comparable with those reported in previous studies. Higher caseloads were associated with higher levels of work-related stress and lower levels of case manager personal efficacy. Active monitoring of caseload was associated with lower scores for work-related stress and higher scores for case manager personal efficacy, regardless of size of caseload. Although caseloads were most frequently monitored by the case manager, there was evidence that monitoring by a supervisor was more beneficial than self-monitoring. Conclusion: Routine monitoring of caseload, especially by a workplace supervisor, may be effective in reducing work-related stress and enhancing case manager personal efficacy. Keywords: case management, caseload, stress

Work-Related Subjective Experiences, Work-Related Self-Efficacy, and Career Learning Among People with Psychiatric Disabilities

Work-related subjective experiences and work-related self-efficacy were investigated as candidate correlates of career learning among people with schizophrenia and schizoaffective disorder. Work-related self-efficacy was expected to mediate any observed relationship between work-related subjective experiences and employment status, after controlling for demographic, vocational, and clinical covariates. Baseline measures (n 1 = 104) were repeated at six months (n 2 = 94) and 12 months (n 3 = 94). Work-related subjective experiences and work-related self-efficacy were consistently associated with current employment after controlling for covariates. The proposed mediator role of work-related self-efficacy remains a viable hypothesis requiring further investigation. Both work-related subjective experiences and work-related self-efficacy appear promising as components of the social cognitive career learning theory to help explain career development among people with psychiatric disabilities.

Work-related self-efficacy among community residents with psychiatric disabilities

A new measure of work-related self-efficacy for people with psychiatric disabilities is reported. The 37-item scale measures self-efficacy in four relevant activity domains: 1) vocational service access and career planning, 2) job acquisition, 3) work-related social skills, and 4) general work skills. The scale was developed in a 12-month longitudinal survey of urban residents diagnosed with schizophrenia or schizoaffective disorder (n = 104). Results indicate validity of both a four-factor structure differentiating four core skill domains, and a single factor representing total work-related self-efficacy. The favorable psychometric properties support further research and trial applications in supported employment and psychiatric vocational rehabilitation.

The PSS : From Flat Maps to Layered Perspectives - the contribution of the Airport Metropolis Planning Support System (PSS) to sub-regional planning in the Brisbane Airport case environment

Conventional planning and decision making, with its sectoral and territorial emphasis and flat-map based processes are no longer adequate or appropriate for the increased complexity confronting airport/city interfaces. These crowed and often contested governance spaces demand a more iterative and relational planning and decision-making approach. Emergent GIS based planning and decision-making tools provide a mechanism which integrate and visually display an array of complex data, frameworks and scenarios/expectations, often in ‘real time’ computations. In so doing, these mechanisms provide a common ground for decision making and facilitate a more ‘joined-up’ approach to airport/city planning. This paper analyses the contribution of the Airport Metropolis Planning Support System (PSS) to sub-regional planning in the Brisbane Airport case environment.