Dynamics of pattern writing and erasure in photorefractive lithium niobate for data storage applications

The present rate of technological advance continues to place significant demands on data storage devices. The sheer amount of digital data being generated each year along with consumer expectations, fuels these demands. At present, most digital data is stored magnetically, in the form of hard disk drives or on magnetic tape. The increase in areal density (AD) of magnetic hard disk drives over the past 50 years has been of the order of 100 million times, and current devices are storing data at ADs of the order of hundreds of gigabits per square inch. However, it has been known for some time that the progress in this form of data storage is approaching fundamental limits. The main limitation relates to the lower size limit that an individual bit can have for stable storage. Various techniques for overcoming these fundamental limits are currently the focus of considerable research effort. Most attempt to improve current data storage methods, or modify these slightly for higher density storage. Alternatively, three dimensional optical data storage is a promising field for the information storage needs of the future, offering very high density, high speed memory. There are two ways in which data may be recorded in a three dimensional optical medium; either bit-by-bit (similar in principle to an optical disc medium such as CD or DVD) or by using pages of bit data. Bit-by-bit techniques for three dimensional storage offer high density but are inherently slow due to the serial nature of data access. Page-based techniques, where a two-dimensional page of data bits is written in one write operation, can offer significantly higher data rates, due to their parallel nature. Holographic Data Storage (HDS) is one such page-oriented optical memory technique. This field of research has been active for several decades, but with few commercial products presently available. Another page-oriented optical memory technique involves recording pages of data as phase masks in a photorefractive medium. A photorefractive material is one by which the refractive index can be modified by light of the appropriate wavelength and intensity, and this property can be used to store information in these materials. In phase mask storage, two dimensional pages of data are recorded into a photorefractive crystal, as refractive index changes in the medium. A low-intensity readout beam propagating through the medium will have its intensity profile modified by these refractive index changes and a CCD camera can be used to monitor the readout beam, and thus read the stored data. The main aim of this research was to investigate data storage using phase masks in the photorefractive crystal, lithium niobate (LiNbO3). Firstly the experimental methods for storing the two dimensional pages of data (a set of vertical stripes of varying lengths) in the medium are presented. The laser beam used for writing, whose intensity profile is modified by an amplitudemask which contains a pattern of the information to be stored, illuminates the lithium niobate crystal and the photorefractive effect causes the patterns to be stored as refractive index changes in the medium. These patterns are read out non-destructively using a low intensity probe beam and a CCD camera. A common complication of information storage in photorefractive crystals is the issue of destructive readout. This is a problem particularly for holographic data storage, where the readout beam should be at the same wavelength as the beam used for writing. Since the charge carriers in the medium are still sensitive to the read light field, the readout beam erases the stored information. A method to avoid this is by using thermal fixing. Here the photorefractive medium is heated to temperatures above 150�C; this process forms an ionic grating in the medium. This ionic grating is insensitive to the readout beam and therefore the information is not erased during readout. A non-contact method for determining temperature change in a lithium niobate crystal is presented in this thesis. The temperature-dependent birefringent properties of the medium cause intensity oscillations to be observed for a beam propagating through the medium during a change in temperature. It is shown that each oscillation corresponds to a particular temperature change, and by counting the number of oscillations observed, the temperature change of the medium can be deduced. The presented technique for measuring temperature change could easily be applied to a situation where thermal fixing of data in a photorefractive medium is required. Furthermore, by using an expanded beam and monitoring the intensity oscillations over a wide region, it is shown that the temperature in various locations of the crystal can be monitored simultaneously. This technique could be used to deduce temperature gradients in the medium. It is shown that the three dimensional nature of the recording medium causes interesting degradation effects to occur when the patterns are written for a longer-than-optimal time. This degradation results in the splitting of the vertical stripes in the data pattern, and for long writing exposure times this process can result in the complete deterioration of the information in the medium. It is shown in that simply by using incoherent illumination, the original pattern can be recovered from the degraded state. The reason for the recovery is that the refractive index changes causing the degradation are of a smaller magnitude since they are induced by the write field components scattered from the written structures. During incoherent erasure, the lower magnitude refractive index changes are neutralised first, allowing the original pattern to be recovered. The degradation process is shown to be reversed during the recovery process, and a simple relationship is found relating the time at which particular features appear during degradation and recovery. A further outcome of this work is that the minimum stripe width of 30 ìm is required for accurate storage and recovery of the information in the medium, any size smaller than this results in incomplete recovery. The degradation and recovery process could be applied to an application in image scrambling or cryptography for optical information storage. A two dimensional numerical model based on the finite-difference beam propagation method (FD-BPM) is presented and used to gain insight into the pattern storage process. The model shows that the degradation of the patterns is due to the complicated path taken by the write beam as it propagates through the crystal, and in particular the scattering of this beam from the induced refractive index structures in the medium. The model indicates that the highest quality pattern storage would be achieved with a thin 0.5 mm medium; however this type of medium would also remove the degradation property of the patterns and the subsequent recovery process. To overcome the simplistic treatment of the refractive index change in the FD-BPM model, a fully three dimensional photorefractive model developed by Devaux is presented. This model shows significant insight into the pattern storage, particularly for the degradation and recovery process, and confirms the theory that the recovery of the degraded patterns is possible since the refractive index changes responsible for the degradation are of a smaller magnitude. Finally, detailed analysis of the pattern formation and degradation dynamics for periodic patterns of various periodicities is presented. It is shown that stripe widths in the write beam of greater than 150 ìm result in the formation of different types of refractive index changes, compared with the stripes of smaller widths. As a result, it is shown that the pattern storage method discussed in this thesis has an upper feature size limit of 150 ìm, for accurate and reliable pattern storage.

Assessing and learning in internships: Reflecting on pedagogy and progress

An elective internship unit as part of a work integrated learning program in a business faculty is presented as a case study. In the unit, students complete a minimum of 120 hours work placement over the course of a 13 week semester. The students are majoring in advertising, marketing, or public relations and are placed in corporations, government agencies, and not for profit organisations. To support and scaffold the students’ learning in the work environment, a range of classroom and online learning activities are part of the unit. Classroom activities include an introductory workshop to prepare students for placement, an industry panel, and interview workshop. These are delivered as three workshops across the semester. Prior to commencing their placement, students complete a suite of online learning modules. The Work Placement Preparation Program assists students in securing obtaining a placement and make a successful transition to the work environment. It provides an opportunity for students to source possible work placement sites, prepare competitive applications, develop and rehearse interview skills, deal with workplace issues, and use a student ePortfolio to reflect on their skills and achievements. Students contribute to a reflective blog throughout their placement, with feedback from academic supervisors throughout the placement. The completion of the online learning modules and contribution to a reflective blog are assessed as part of the unit. Other assessment tools include a internship plan and learning contract between the student, industry supervisor, and academic supervisor; job application including responses to selection criteria; and presentation to peers, academics and industry representatives at a poster session. The paper discusses the development of the internship unit over three years, particularly learning activities and assessment. The reflection and refinement of the unit is informed by a pedagogical framework, and the development of processes to best manage placement for all stakeholders. A model of best practice is proposed, that can be adapted to a variety of discipline areas.

Developing reflective practitioners online: The business of blogs in work integrated learning

Reflective practice is widely considered across discussions around educational psychology, professional identity, employability of graduates, and generic or graduate capabilities. Critical reflection is essential for providing a bridge between the university and the workplace, and for ultimately preparing work ready graduates (Patrick et al, 2008). Work integrated learning, particularly through internships and work placements for students, is viewed as a valuable approach for students developing skills in reflective practice. Reflective journals are one of the tools often used to encourage and develop student reflection. Shifting the reflective journal to an online interface as a reflective blog presents opportunities for more meaningful, frequent and richer interaction between the key players in a work integrated learning experience. This paper examines the adoption, implementation and refinement of the use of reflective blogs in a work integrated learning unit for business students majoring in advertising, marketing and public relations disciplines. The reflective blog is discussed as a learning and assessment tool, including the approaches taken to integrate and scaffold the blog as part of the work integrated learning experience. Graduate capabilities were used as cornerstones for students to frame students’ thinking, experiences and reflection. These capabilities emphasise the value of coherent theoretical and practical knowledge, coupled with critical, creative and analytical thinking, problem solving skills, self reliance and resilience. Underlying these graduate capabilities is a focus on assessment for learning matched with assessment of learning. Using specific triggers and prompts as part of the reflective process, and incorporating ongoing feedback from academic supervisors, students moved from descriptive levels of reflection, to more meaningful and critical reflection. Students’ blogs are analysed to identify key themes, challenges and achievements in the work integrated learning experience. Suggestions for further development and improvement, together with a model of best practice, are proposed.

Seeking a life in the literary position : the writing of Charmian Clift

An examination of the published and unpublished writing of Charmian Clift.

Implementing the international : challenges and approaches

This paper documents some preliminary findings arising from our Creative Industries Faculty’s invitation to academics to submit suitable proposals for Internationalising the Curriculum, an initiative that aligns with the University’s recognition of the importance of “building international components into their teaching programs” Our research project involves revisiting the literature on internationalising the curriculum with a view to implementing pedagogic and assessment strategies that respect and encourage intercultural and international understandings and competencies. The paper addresses the problems in designing such a unit; in this case an American Literature unit which will be taught and studied in Australia at QUT in 2011. The challenges inherent in the task of internationalising the curriculum stem from the ‘traditional’ and accepted ways of structuring and delivering such units. While the content may be international, the problem remains as to how to go about teaching and assessing the unit to achieve a global approach. How can it be taught in a way that steps outside the borders of our national teaching practices and understanding of western epistemology and becomes far more inclusive of other modes of knowledge?

International students in Australian universities : gap between student expectations and realities

Australian Universities are very successful in attracting large number of international students. A large proportion of University revenue comes from the full fee paying international students. However, there have been many reports that international students face numerous problems when they arrive in Australia. The common management practice is to provide support staff services to deal with the orientation and welfare of international students. Such service units act as intermediaries between the students and the teaching and learning community of the university. However, the actual experience of international students may be difficult for support staff, counsellors, advisers and academic staff to anticipate. There is little information on the actual experience of students relative to their expectations. This study aimed at securing a deeper understanding of the contextually relevant issues facing by international students in Australian universities in order to develop management strategies aimed at improved teaching and learning outcomes for international students. Using a highly reliable survey questionnaire, a questionnaire survey was conducted among the international students at Queensland University of Technology (QUT), Brisbane, Australia. About 180 engineering students responded in the survey resulting in a response rate of 81%. Results indicate that international students face many difficulties including understanding colloquial language, Australian accent, cost of tuition, feelin isolation, safety, security, health services, accommodation and part time jobs. They also face difficulty in coping with learning methods in Australia, particularly in research report writing. However, they are happy with their lecturers and find them very helpful. Many of the students lacked the information regarding various community groups, recreational and sports facilities in Australia before arriving. Findings of the study show that there is a significant gap between the expectation of the students before coming to Australia and actual experience they experience here. Importantly, there is a lack of coordination between international students, international student services (ISS) and university management and as a consequence there have been little improvement in conditions. There is no direct link between student experience and University management. Many important suggestions arisen from this study and most important suggestion is that the student information system should be integrated with the University enterprise resource planning (ERP) to reduce the huge gap between international student expectation and actual experiences.

Pedagogy and participation : literacy education for low-literate refugee students of African origin in a western school system

For ESL teachers working with low-literate adolescents the challenge is to provide instruction in basic literacy capabilities while also realising the benefits of interactive and dialogic pedagogies advocated for the students. In this article we look at literacy pedagogy for refugees of African origin in Australian classrooms. We report on an interview study conducted in an intensive English language school for new arrival adolescents and in three regular secondary schools. Brian Street’s ideological model is used. From this perspective, literacy entails not only technical skills, but also social and cultural ways of making meaning that are embedded within relations of power. The findings showed that teachers were strengthening control of instruction to enable mastery of technical capabilities in basic literacy and genre analysis. We suggest that this approach should be supplemented by a critical approach transforming relations of linguistic power that exclude, marginalise and humiliate the study students in the classroom.

Student engagement with an ePortfolio : a case study of pre-service education students

The emergence of ePortfolios is relatively recent in the university sector as a way to engage students in their learning and assessment, and to produce records of their accomplishments. An ePortfolio is an online tool that students can utilise to record, catalogue, retrieve and present reflections and artefacts that support and demonstrate the development of graduate students’ capabilities and professional standards across university courses. The ePortfolio is therefore considered as both process and product. Although ePortfolios show promise as a useful tool and their uptake has grown, they are not yet a mainstream higher education technology. To date, the emphasis has been on investigating their potential to support the multiple purposes of learning, assessment and employability, but less is known about whether and how students engage with ePortfolios in the university setting. This thesis investigates student engagement with an ePortfolio in one university. As the educational designer for the ePortfolio project at the University, I was uniquely positioned as a researching professional to undertake an inquiry into whether students were engaging with the ePortfolio. The participants in this study were a cohort (defined by enrolment in a unit of study) of second and third year education students (n=105) enrolled in a four year Bachelor of Education degree. The students were introduced to the ePortfolio in an introductory lecture and a hands-on workshop in a computer laboratory. They were subsequently required to complete a compulsory assessment task – a critical reflection - using the ePortfolio. Following that, engagement with the ePortfolio was voluntary. A single case study approach arising from an interpretivist paradigm directed the methodological approach and research design for this study. The study investigated the participants’ own accounts of their experiences with the ePortfolio, including how and when they engaged with the ePortfolio and the factors that impacted on their engagement. Data collection methods consisted of an attitude survey, student interviews, document collection, a researcher reflective journal and researcher observations. The findings of the study show that, while the students were encouraged to use the ePortfolio as a learning and employability tool, most students ultimately chose to disengage after completing the assessment task. Only six of the forty-five students (13%) who completed the research survey had used the ePortfolio in a sustained manner. The data obtained from the students during this research has provided insight into reasons why they disengaged from the ePortfolio. The findings add to the understandings and descriptions of student engagement with technology, and more broadly, advance the understanding of ePortfolios. These findings also contribute to the interdisciplinary field of technology implementation. There are three key outcomes from this study, a model of student engagement with technology, a set of criteria for the design of an ePortfolio, and a set of recommendations for effective practice for those implementing ePortfolios. The first, the Model of Student Engagement with Technology (MSET) (Version 2) explored student engagement with technology by highlighting key engagement decision points for students The model was initially conceptualised by building on work of previous research (Version 1), however, following data analysis a new model emerged, MSET (Version 2). The engagement decision points were identified as: • Prior Knowledge and Experience, leading to imagined usefulness and imagined ease of use; • Initial Supported Engagement, leading to supported experience of usefulness and supported ease of use; • Initial Independent Engagement, leading to actual experience of independent usefulness and actual ease of use; and • Ongoing Independent Engagement, leading to ongoing experience of usefulness and ongoing ease of use. The Model of Student Engagement with Technology (MSET) goes beyond numerical figures of usage to demonstrate student engagement with an ePortfolio. The explanatory power of the model is based on the identification of the types of decisions that students make and when they make them during the engagement process. This model presents a greater depth of understanding student engagement than was previously available and has implications for the direction and timing of future implementation, and academic and student development activities. The second key outcome from this study is a set of criteria for the re-conceptualisation of the University ePortfolio. The knowledge gained from this research has resulted in a new set of design criteria that focus on the student actions of writing reflections and adding artefacts. The process of using the ePortfolio is reconceptualised in terms of privileging student learning over administrative compliance. The focus of the ePortfolio is that the writing of critical reflections is the key function, not the selection of capabilities. The third key outcome from this research consists of five recommendations for university practice that have arisen from this study. They are that, sustainable implementation is more often achieved through small steps building on one another; that a clear definition of the purpose of an ePortfolio is crucial for students and staff; that ePortfolio pedagogy should be the driving force not the technology; that the merit of the ePortfolio is fostered in students and staff; and finally, that supporting delayed task performance is crucial. Students do not adopt an ePortfolio just because it is provided. While students must accept responsibility for their own engagement with the ePortfolio, the institution has to accept responsibility for providing the environment, and technical and pedagogical support to foster engagement. Ultimately, an ePortfolio should be considered as a joint venture between student and institution where strong returns on investment can be realised by both. It is acknowledged that the current implementation strategies for the ePortfolio are just the beginning of a much longer process. The real rewards for students, academics and the university lie in the future.

Children re-read and re-write their neighborhoods : critical literacies and identity work

This chapter considers the complex literate repertoires of 21st century children in multicultural primary classrooms in Adelaide South Australia. It draws on the curricular and pedagogical work of two experienced primary school teachers who explore culture, race and class, by positioning children as textual producers across a variety of media. In particular we discuss two child-authored texts – A is for Arndale – a local alphabet book co-authored by children aged between eight and ten, and – Cooking Afghani Style - a magazine style film produced by a multi-aged class of children (aged eight to thirteen) recently arrived in Australia. In the process of making these texts, primary children engaged in reading as a cultural practice – re-reading and re-writing their neighbourhoods and identities (both individual and collective). This involved frequent excursions to local key sites, both familiar and unfamiliar to the children. They investigated how diverse children experienced and lived their lives in particular places within changing communities.

New research literacies for contemporary research into literacy and new media?

The term literacy remains highly contested and debates continue about how literacy might best be researched and to what ends. For some, literacy is simply a matter of acquiring the technical competence which enables people to read and write. Literacy research conducted from this point of view does not usually concern itself with the new media but rather focuses on how people learn to code and decode print text. For others, however, literacy is more complex and involves learning a repertoire of practices for communicating and getting things done in particular social and cultural contexts. Literacy research conducted from this sociocultural point of view accepts that the new media are central to the field because in everyday cultural practice people are using the new media to make meaning, to express themselves and to communicate and work with others. Socio-cultural approaches to literacy research have already provided rich material which has assisted educators to understand literacy practices in everyday use (e.g. Barton & Hamilton, 1998; Barton, Hamilton and Ivanic, 2000) including children’s appropriation of the media in school-based writing (Dyson, 1997). However, the changing semiotic and cultural practices associated with new media and online participation have less frequently been the object of study...

Preparing students for international study : the use of technology

About 1.6 million students currently study outside their home country. Despite this, and the fact that Australia, the United States, the United Kingdom and many of the other host countries of international students are themselves extremely culturally diverse communities, business education remains essentially mono-cultural in form and Anglo American in content. Whilst it is true that these international students may want to understand the "Western" way of doing things, they may not be familiar or comfortable with the processes used to facilitate learning. This paper explores a project undertaken to create a tool that provides essential pre-orientation information and advice to students before they leave home. Where cultural adjustment is required, catching students before departure is a very effective time to introduce key information about lifestyle, culture and approaches to teaching and learning that would assist students with the complex and difficult adjustment to studying abroad, so that they could make a smoother transition to their new place of learning. Welcome to Studying Business at QUT is a Data DVD with 19 short videos capturing a student perspective on life and study. Forty percent of the content is related to living and studying and includes sections on accommodation, lifestyle, food and transport etc., and 60% takes an in-depth look at studying business, featuring students and academics talking about issues such as assessment, academic writing and working in groups. This paper outlines the process of developing the DVD and the range of issues addressed.

Assurance of learning : the role of work integrated learning and industry partners

In the partnering with students and industry it is important for universities to recognize and value the nature of knowledge and learning that emanates from work integrated learning experiences is different to formal university based learning. Learning is not a by-product of work rather learning is fundamental to engaging in work practice. Work integrated learning experiences provide unique opportunities for students to integrate theory and practice through the solving of real world problems. This paper reports findings to date of a project that sought to identify key issues and practices faced by academics, industry partners and students engaged in the provision and experience of work integrated learning within an undergraduate creative industries program at a major metropolitan university. In this paper, those findings are focused on some of the particular qualities and issues related to the assessment of learning at and through the work integrated experience. The findings suggest that the assessment strategies needed to better value the knowledges and practices of the Creative Industries. The paper also makes recommendations about how industry partners might best contribute to the assessment of students’ developing capabilities and to continuous reflection on courses and the assurance of learning agenda.

Doing justice : young people’s representations of the Murray-Darling Basin

The business of helping children to grow up as ‘custodians’, or ‘future managers’ of the Murray-Darling Basin is not simple, and that single sources of information and ways of seeing the environment are not enough. Children (and adults) need to be able to relate individually, emotionally and aesthetically to their places if they are to learn to love them. However, they also need access to a variety of ways of thinking and seeing those same places if they are to be able to take action to sustain them – action that inevitably involves forms of communication with their fellow citizens. This chapter documents the writing and art program Special Forever, with its focus on communications, as an important intervention into promoting eco-social sustainability.

Spatial literacies, design texts and emergent pedagogies in purposeful literacy curriculum

There has recently been an emphasis within literacy studies on both the spatial dimensions of social practices (Leander & Sheehy, 2004) and the importance of incorporating design and multiple modes of meaning-making into contemporary understandings of literacy (Cope & Kalantzis, 2000; New London Group, 1996). Kress (2003) in particular has outlined the potential implications of the cultural shift from the dominance of writing, based on a logic of time and sequence in time, to the dominance of the mode of the image, based on a logic of space. However, the widespread re-design of curriculum and pedagogy by classroom teachers to allow students to capitalise on the various affordances of different modes of meaning-making – including the spatial – remains in an emergent stage. We report on a project in which university researchers’ expertise in architecture, literacy and communications enabled two teachers in one school to expand the forms of literacy that primary school children engaged in. Starting from the school community’s concerns about an urban renewal project in their neighbourhood, we worked together to develop a curriculum of spatial literacies with real-world goals and outcomes.

Teachers' work and pedagogy in an era of accountability

A great deal of educational policy proceeds as though teachers are malleable and ever-responsive to change. Some argue they are positioned as technicians who simply implement policy. However, how teachers go about their work and respond to reform agendas may be contingent upon many factors that are both biographical in nature and workplace related. In this paper we discuss the work of middle school teachers in low-socioeconomic communities from their perspectives. Referring to reflective interviews, meeting transcripts and an electronic reporting template, we examine how teacher participants in a school reform project describe their work - what they emphasise and what they down-play or omit. Using Foucaultian approaches to critical discourse analysis and insights from Dorothy Smith's (2005) Institutional Ethnography, we consider the 'discursive economy' (Carlson, 2005) in teachers' reported experiences of their everyday practices in northern suburbs schools in South Australia in which a democratic progressive discourse exists alongside corporate and disciplinary discourses.