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.

Producing the intercultural citizen in the International Baccalaureate

The International Baccalaureate Diploma (IBD) is currently offered in 2,718 schools across 138 countries, and explicitly aims to produce ‘internationally-minded’ citizens with a sense of belonging to both the local and the global community. It thus offers an opportunity to enquire how a school curriculum might produce more intercultural or global dispositions, knowledge and skills, and the challenges inherent in such design. To frame this empirical enquiry, the chapter distinguishes between the fact of living together in difference as a life circumstance, and a range of ethical dispositions for such living together, including cosmopolitanism, internationalism, interculturality and global citizenship. These alternatives are understood as competing social imaginaries with different premises and logics. This chapter offers an empirical exploration of how the IBD’s curricular goal of ‘international-mindedness’ is interpreted firstly in current official documents, then reinterpreted by teachers and students in three case study schools in Australia. Traces of these overlapping but distinct discourses are found in the teachers’ recontextualisation of the IBD’s ‘internationalmindedness’ producing diffuse and contradictory versions of what ‘internationalmindedness’ means, and looks like in educational settings.

Analysing mentoring dialogues for developing a preservice teacher’s classroom management practices

Mentors (cooperating classroom teachers) have a shared responsibility with universities for developing preservice teachers’ pedagogical practices, particularly towards becoming reflective practitioners. Preservice teachers need to participate actively in their own learning, by reflecting and acting on the mentor’s constructive feedback provided during planning and feedback dialogue sessions. This case study uses feedback practices outlined within a five-factor mentoring model to analyse dialogue between a mentor and her respective mentee during different stages in their school-based programs (first practicum). This investigation uses multiple data sources such as video and audio-recorded interviews, archival documents from participants such as lesson plans, reflections and reports to examine preservice teacher’s reflections and implementations of practice as a result of her mentor’s feedback (e.g., establish expectations, review lesson plans, observe teaching then provide oral and written feedback, and evaluate progress). Findings indicated that reflective thinking was more apparent when the mentor did not dominate conversations but instead asked astute pedagogical knowledge questions to facilitate the mentee’s reflections on practice.

Engaging middle school students in context-based science : One teacher's approach

In Australia, there is a crisis in science education with students becoming disengaged with canonical science in the middle years of schooling. One recent initiative that aims to improve student interest and motivation without diminishing conceptual understanding is the context-based approach. Contextual units that connect the canonical science with the students’ real world of their local community have been used in the senior years but are new in the middle years. This ethnographic study explored the learning transactions that occurred in one 9th grade science class studying an Environmental Science unit for 11 weeks. Data were derived from field notes, audio and video recorded conversations, interviews, student journals and classroom documents with a particular focus on two selected groups of students. Data were analysed qualitatively through coding for emergent themes. This paper presents an outline of the program and discussion of three assertions derived from the preliminary analysis of the data. Firstly, an integrated, coherent sequence of learning experiences that included weekly visits to a creek adjacent to the school enabled the teacher to contextualise the science in the students’ local community. Secondly, content was predominantly taught on a need-to-know basis and thirdly, the lesson sequence aligned with a model for context-based teaching. Research, teaching and policy implications of these results for promoting the context-based teaching of science in the middle years are discussed.

Children’s strategies for making friends when starting school

Starting school is a critical and potentially stressful time for many young children, and having supportive relationships with parents, teachers and peers and friends offer better outcomes for school adjustment and social relationships. This paper explores matters of friendship when young children are starting school, and how they initiate friendships. In audio-recorded conversations with a researcher and their peers, the children proposed a number of strategies, including making requests, initiating clubs and teams, and peer intervention to support a friend. Their accounts drew on social knowledge and relational understandings, and showed that having someone, a friend, to play with was important for starting school. Children gave serious attention to developing strategies to initiate friendships.

The iPhone Moment, the Apple Brand and the creative consumer : From “hackability and usability” to cultural generativity

In this chapter I position the iPhone as a “moment” in the history of cultural technologies. Drawing predominantly on advertising materials and public conversations about other "moments" in the history of personal computing and focusing on Apple’s role in this history, I argue that the design philosophy, marketing, and business models behind the iPhone (and now the iPad) have decisively reframed the values of usability that underpin software and interface design in the consumer technology industry, marking a distinctive shift in the history and contested futures of digital culture.

An investigation into online moderation

The purpose of this paper is to understand how teachers’ identity as an assessor in a standards-referenced assessment system may be developed through their participation in online social moderation meetings. In these meetings teachers negotiate and share their understandings of assessment standards and judgement decisions. In particular, the paper focuses on the relationship between the technology, the moderation processes and teachers’ development in this assessment system. This paper draws on sociocultural theories of learning to analyse the qualitative data collected through observations of eleven online moderation meetings and interviews of the teachers involved in these meetings. The results provide insights into the mediating role of the technology with regard to teachers’ development of shared meanings and common practices within a standards-referenced assessment system.

Multiple perspectives on engaging future engineers

Engaging future engineers is a central topic in everyday conversations on engineering education. Considerable investments have been made to make engineering more engaging, recruit and retain aspiring engineers, and to design an education to prepare future engineers. However, the impact of these efforts has been less than intended. It is imperative that the community reflects on progress and sets a more effective path for the future.

ICT as core business: will we prosper or drown?

Recent changes in IT organisations have resulted in changes to library IT support. Concurrently, new tools and systems for service delivery, have become available, but these require a move away from the traditional ICT model. Many libraries are investigating new models, including Software as a Service (SaaS), cloud computing and open source software. This paper considers whether the adoption of these tools and environments by libraries has occurred as a result of a lack of suitable ICT solutions and support ICT organisations. It also considers what skills library staff need in order to ensure sustainability, supportability, and ultimately, success.

Learning as identity and practice through involvement in online moderation

For teachers working in a standards-based assessment system, professional conversations through organised social moderation meetings are a vital element. This qualitative research investigated the learning that occurred as a result of online moderation discussions. Findings illustrate how participating in social moderation meetings in an online context can support teachers to understand themselves as assessors, and can provide opportunities for teachers to imagine possibilities for their teaching that move beyond the moderation practice.

How long is a tweet? Mapping dynamic conversation networks on Twitter using Gawk and Gephi

Twitter is now well established as the world’s second most important social media platform, after Facebook. Its 140-character updates are designed for brief messaging, and its network structures are kept relatively flat and simple: messages from users are either public and visible to all (even to unregistered visitors using the Twitter website), or private and visible only to approved ‘followers’ of the sender; there are no more complex definitions of degrees of connection (family, friends, friends of friends) as they are available in other social networks. Over time, Twitter users have developed simple, but effective mechanisms for working around these limitations: ‘#hashtags’, which enable the manual or automatic collation of all tweets containing the same #hashtag, as well allowing users to subscribe to content feeds that contain only those tweets which feature specific #hashtags; and ‘@replies’, which allow senders to direct public messages even to users whom they do not already follow. This paper documents a methodology for extracting public Twitter activity data around specific #hashtags, and for processing these data in order to analyse and visualize the @reply networks existing between participating users – both overall, as a static network, and over time, to highlight the dynamic structure of @reply conversations. Such visualizations enable us to highlight the shifting roles played by individual participants, as well as the response of the overall #hashtag community to new stimuli – such as the entry of new participants or the availability of new information. Over longer timeframes, it is also possible to identify different phases in the overall discussion, or the formation of distinct clusters of preferentially interacting participants.

The enterprising artist and the arts entrepreneur : Emergent pedagogies for new disciplinary habits of mind

Traditional pedagogies in the arts in higher education focus largely on the studio experience in which a novice artist studies under one or more master teachers (e.g., Don, Garvey, & Sadeghpour, 2009). In more recent times, however, a shift in higher education curriculum and pedagogy in the arts has expanded this traditional conservatory model of training to include, among other components, career self-management and enterprise creation—in a word, entrepreneurship.This chapter examines the developing field of arts enterprise and arts entrepreneurship in higher education in a multinational context. The field is contextualized within the broader landscape of the creative industries and the consequential development of knowledge, skills, and the habits of mind necessary for artistic venture creation, sustainability, and success. Whereas the discourse about learning and teaching for business entrepreneurship is well established (e.g., Fiet, 2001), equivalent conversations about arts enterprise and entrepreneurship have only recently begun (Beckman, 2007, 2011; Essig, 2009). This chapter will address the contested definitions of key terms and concepts and also the question of how arts educators, although mindful of the pedagogic traditions of the arts school, are also drawing on the pedagogies of business entrepreneurship and cognitive theories of entrepreneurship to create innovative new transdisciplinary signature pedagogies for creative enterprise and entrepreneurship education in the arts.

Teaching English : some remarks on the emergence of the sympathetic teacher in the English classroom

The chapter explores the concept of the teacher-student relationship within the English classroom and proposes that this relationship has a specific purpose in building a civil society by inculcating practices of self-reflection, empathy and ethics. The topic is explored through the example of teaching Australian literature, specifically, Tim Winton’s Lockie Leonard, Human Torpedo to secondary school students. Ian Hunter’s work on literature education and the construction of socio-ethical practices provides a conceptual framework for the chapter.

Fundamentals of process integration

Technologies and languages for integrated processes are a relatively recent innovation. Over that period many divergent waves of innovation have transformed process integration. Like sockets and distributed objects, early workflow systems ordered programming interfaces that connected the process modelling layer to any middleware. BPM systems emerged later, connecting the modelling world to middleware through components. While BPM systems increased ease of use (modelling convenience), long-standing and complex interactions involving many process instances remained di±cult to model. Enterprise Service Buses (ESBs), followed, connecting process models to heterogeneous forms of middleware. ESBs, however, generally forced modellers to choose a particular underlying middleware and to stick to it, despite their ability to connect with many forms of middleware. Furthermore ESBs encourage process integrations to be modelled on their own, logically separate from the process model. This can lead to the inability to reason about long standing conversations at the process layer. Technologies and languages for process integration generally lack formality. This has led to arbitrariness in the underlying language building blocks. Conceptual holes exist in a range of technologies and languages for process integration and this can lead to customer dissatisfaction and failure to bring integration projects to reach their potential. Standards for process integration share similar fundamental flaws to languages and technologies. Standards are also in direct competition with other standards causing a lack of clarity. Thus the area of greatest risk in a BPM project remains process integration, despite major advancements in the technology base. This research examines some fundamental aspects of communication middleware and how these fundamental building blocks of integration can be brought to the process modelling layer in a technology agnostic manner. This way process modelling can be conceptually complete without becoming stuck in a particular middleware technology. Coloured Petri nets are used to define a formal semantics for the fundamental aspects of communication middleware. They provide the means to define and model the dynamic aspects of various integration middleware. Process integration patterns are used as a tool to codify common problems to be solved. Object Role Modelling is a formal modelling technique that was used to define the syntax of a proposed process integration language. This thesis provides several contributions to the field of process integration. It proposes a framework defining the key notions of integration middleware. This framework provides a conceptual foundation upon which a process integration language could be built. The thesis defines an architecture that allows various forms of middleware to be aggregated and reasoned about at the process layer. This thesis provides a comprehensive set of process integration patterns. These constitute a benchmark for the kinds of problems a process integration language must support. The thesis proposes a process integration modelling language and a partial implementation that is able to enact the language. A process integration pilot project in a German hospital is brie°y described at the end of the thesis. The pilot is based on ideas in this thesis.

Analysing mentoring practices to understand how a preservice teacher reflects on practice to advance teaching

Mentors (cooperating classroom teachers) have a shared responsibility with universities for developing preservice teachers’ pedagogical practices, particularly towards becoming reflective practitioners. Preservice teachers need to participate actively in their own learning, by reflecting and acting on the mentor’s constructive feedback provided during planning and feedback dialogue sessions. This case study uses feedback practices outlined within a five-factor mentoring model to analyse dialogue between a mentor and her respective mentee during different stages in their school-based programs (first practicum). This investigation uses multiple data sources such as video and audio-recorded interviews, archival documents from participants such as lesson plans, reflections and reports to examine preservice teacher’s reflections and implementations of practice as a result of her mentor’s feedback (e.g., establish expectations, review lesson plans, observe teaching then provide oral and written feedback, and evaluate progress). Findings indicated that reflective thinking was more apparent when the mentor did not dominate conversations but instead asked astute pedagogical knowledge questions to facilitate the mentee’s reflections on practice.