Experiments and their analysis for self-assembly growth of GaN quantum dots via MOCVD

In recent years, growth of GaN-based materials-related quantum dots has become a hot topic in semiconductor materials research. Considerable efforts have been devoted to growth of self-assembled quantum dots of GaN-based materials via MOCVD (Metal Organic Chemical Vapor Deposition) and there are a lot of relevant literatures. There is, however, few review papers for the topic. In this paper, different experimental methods for fabrication of quantum dots of GaN-based materials via MOCVD are critically reviewed and the experimental conditions and parameters, which may affect growth of the quantum dots, are analyzed, with an aim at providing some critical reference for the related future experiment research.

High power continuous-wave operation of self-organized In(Ga)As/GaAs quantum dot lasers

Quantum dot (QD) lasers are expected to have superior properties over conventional quantum well lasers due to a delta-function like density of states resulting from three dimensional quantum confinements. QD lasers can only be realized till significant improvements in uniformity of QDs with free of defects and increasing QD density as well in recent years. In this paper, we first briefly give a review on the techniques for preparing QDs, and emphasis on strain induced self-organized quantum dot growth. Secondly, self-organized In(Ga)As/GaAs, InAlAs/GaAlAs and InAs/InAlAs Qds grown on both GaAs and InP substrates with different orientations by using MBE and the Stranski-Krastanow (SK) growth mode at our labs are presented. Under optimizing the growth conditions such as growth temperature, V/III ratio, the amount of InAs, InxGa1-xAs, InxAl1-xAs coverage, the composition x etc., controlling the thickness of the strained layers, for example, just slightly larger than the critical thickness and choosing the substrate orientation or patterned substrates as well, the sheet density of ODs can reach as high as 10(11) cm(-2), and the dot size distribution is controlled to be less than 10% (see Fig. 1). Those are very important to obtain the lower threshold current density (J(th)) of the QD Laser. How to improve the dot lateral ordering and the dot vertical alignment for realizing lasing from the ground states of the QDs and further reducing the Jth Of the QD lasers are also described in detail. Thirdly based on the optimization of the band engineering design for QD laser and the structure geometry and growth conditions of QDs, a 1W continuous-wave (cw) laser operation of a single composite sheet or vertically coupled In(Ga)As quantum dots in a GaAs matrix (see Fig. 2) and a larger than 10W semiconductor laser module consisted nineteen QD laser diodes are demonstrated. The lifetime of the QD laser with an emitting wavelength around 960nm and 0.613W cw operation at room temperature is over than 3000 hrs, at this point the output power was only reduced to 0.83db. This is the best result as we know at moment. Finally the future trends and perspectives of the QD laser are also discussed.

Assessing genetic identity of sporophytic offspring of the brown alga Undaria pinnatifida derived from mono-crossing of gametophyte clones by use of amplified fragment length polymorphism and microsatellite markers

The haploid stage of gametophytes of the subtidal brown alga Undaria pinnatifida can be vegetatively propagated under favorable conditions. This unique characteristic makes it possible to establish independent gametophyte cell lines that are zoospore-derived. Sporophytic offspring can be generated through hybridizing the male and female gametophytes, which are derived from different cell lines. Accumulated experiences in this and other species in Laminariales demonstrated the applicability of this novel way to breed desired strains for open-sea cultivation. Sporophytic offspring originated from mono-crossing of male and female gametophyte clones were shown to have similar morphological characteristics under identical ambient conditions. However, there has been no report to relate this similarity on molecular levels. In this report, amplified fragment length polymorphism (AFLP) and microsatellite markers were used to analyze the genetic identity of sporophytic offspring of U. pinnatifida originated from two mono-crossing lines (M1 and M2), two self-breeding lines (S1 and S2) and one wild population (W). Totally 318 AFLP loci were revealed by use of 11 primer sets, of which 4.7%, 0.3%, 17.9%, 16.4% and 36.5% were polymorphic in M1, M2, S1, S2 and W, respectively. The pairwise genetic identity among the individuals of the same line was assessed. It was shown that offspring from mono-crossing lines had a higher degree of identity (95.6-100%) than self-breeding lines (87.7-98.4%) and the wild population (81.5-92.1%). Analysis by use of six microsatellite loci also revealed a higher genetic identity among individuals of the mono-crossing line, further confirming the results of AFLP analysis. Results from this investigation support, on molecular levels, the novel way to produce and maintain strains in U. pinnatifida by use of different gametophyte cell lines.

William Hope Hodgson's borderlands: monstrosity, other worlds, and the future at the fin de siècle.

William Hope Hodgson has generally been understood as the author of several atmospheric sea-horror stories and two powerful but flawed horror science fiction novels. There has been no substantial study analysing the historical and cultural context of his fiction or its place in the Gothic, horror, and science fiction literary traditions. Through analysing the theme of borderlands, this thesis contextualises Hodgson’s novels and short stories within these traditions and within late Victorian cultural discourse. Liminal other world realms, boundaries of corporeal monstrosity, and the imagined future of the world form key elements of Hodgson’s fiction, reflecting the currents of anxiety and optimism characterising fin-de-siècle British society. Hodgson’s early career as a sailor and his interest in body-building and physical culture colour his fiction. Fin-de-siècle discourses of evolution, entropy, spiritualism, psychical research, and the occult also influence his ideas. In The House on the Borderland (1908) and The Night Land (1912), the known world brushes against other forms of reality, exposing humanity to incomprehensible horrors. In The Ghost Pirates (1909), the sea forms a liminal region on the borderland of materiality and immateriality in which other world encounters can take place. In The Night Land and The Boats of the ‘Glen Carrig’ (1907), evolution gives rise to strange monstrous forms existing on the borderlines of species and identity. In Hodgson’s science fiction—The House on the Borderland and The Night Land—the future of the earth forms a temporal borderland of human existence shaped by fin-de-siècle fears of entropy and the heat-death of the sun. Alongside the work of other writers such as H. G. Wells and Arthur Machen, Hodgson’s four novels respond to the borderland discourses of the fin de siècle, better enabling us to understand the Gothic literature of the period as well as Hodgson’s position as a writer who offers a unique imaginative perspective on his contemporary culture.

Super-eruptions: global effects and future threats

Sparks, S. & Self. S. et al., 2005: Super-eruptions: global effects and future threats. Report of a Geological Society of London Working Group (2nd (print) Edn.). Original (Web) edition available at www.geolsoc.org.uk/supereruptions.

Narratives of Holiness Identity: The "Sanctified Person" in the Church of the Nazarene

This dissertation is an exercise in practical theology, which investigates and responds to the problem of changing holiness identity in the Church of the Nazarene. The first part of the study is an empirical investigation into the social context of contemporary Nazarene holiness identity and practices among Nazarenes in three congregations located in the Northeast United States. Previous research relied too heavily on secularization and sect-church theory to understand the dynamics of religious identity change among Nazarenes. The theological result was a pessimistic appraisal of the future possibilities of holiness identity and practice in the Church of the Nazarene. This study employs an alternative theory—Nancy T. Ammerman's theory of narrative religious identity—to understand the dynamics of lived religious life within these congregations and to identify the various holiness narratives at play. Ammerman's theory facilitates an empirical description of the multiple holiness identities emerging out of the social contexts of these Nazarene congregations and offers a way to account for identity change. At the heart of this research is the theoretical notion that a particular religious identity, in the case of the Church of the Nazarene, the "sanctified person," emerges out of a particular ecclesial context characterized by religious narratives and practices that shape this identity. Chapter one reviews the problem of holiness identity in the Church of the Nazarene and offers an analysis of recent sociological attempts to understand the changing identity among Nazarenes. Chapter two draws on sociological research to describe and depict the range of views of holiness held by some contemporary Nazarenes. Chapter three identifies the varieties of holiness identity within the three Nazarene congregations that are part of the study. Chapter four investigates the social sources that shape the various holiness identities discovered in these congregations. Chapter five is a description of the many ways religious narratives are enacted and engaged within these congregations. The second part of the study is a theological critique of contemporary Nazarene holiness identity. Chapter six draws on the theory of narrative identity proposed by Nancy Ammerman and outlines a theoretical model which describes the social conditions necessary to shape holiness identity, "the sanctified person," within the context of the local congregation. Finally, chapter seven draws on the theological resources of Mennonite scholar and historian John Howard Yoder to propose a way of construing and facilitating holiness identity formation that takes the ecclesiality of hoilness more seriously, emphasizes a clearer relationship between Jesus and the "Christlikeness" that is central to holiness, and highlights the importance of religious practices in the formation of a holiness identity.

Work experience in transition year: a mixed methods study of subject and career choices

Transition Year (TY) has been a feature of the Irish Education landscape for 39 years. Work experience (WE) has become a key component of TY. WE is defined as a module of between five and fifteen days duration where students engage in a work placement in the broader community. It places a major emphasis on building relationships between schools and their external communities and concomitantly between students and their potential future employers. Yet, the idea that participation in a TY work experience programme could facilitate an increased awareness of potential careers has drawn little attention from the research community. This research examines the influence WE has on the subsequent subjects choices made by students along with the effects of that experience on the students’ identities and emerging vocational identities. Socio-cultural Learning Theory and Occupational Choice Theory frame the overall study. A mixed methods approach to data collection was adopted through the administration of 323 quantitative questionnaires and 32 individual semi-structured interviews in three secondary schools. The analysis of the data was conducted using a grounded theory approach. The findings from the research show that WE makes a significant contribution to the students’ sense of agency in their own lives. It facilitates the otherwise complex process of subject choice, motivates students to work harder in their senior cycle, introduces them to the concepts of active, experience-based and self-directed learning, while boosting their self-confidence and nurturing the emergence of their personal and vocational identities. This research is a gateway to further study in this field. It also has wide reaching implications for students, teachers, school authorities, parents and policy makers regarding teaching and learning in our schools and the value of learning beyond the walls of the classroom.

A study of the Zhiqing identity

More than seventeen million Chinese urban youth (Zhiqing in Chinese) went to the countryside, lived and engaged in agricultural work there during the Up to the Mountains and Down to the Countryside (UMDC) Movement (1967-1981). Although this movement was officially terminated in 1981, it has left an imprint on these people – the Zhiqing identity by which they are still characterized as a unique group in Chinese society and a special generation in Chinese history. Historical and sociological perspectives are combined in this study. By applying Glen H. Elder’s life course approach, the study reveals how Zhiqing’s life trajectories are embedded in the social history and identifies a series of interrelated factors that made Zhiqing into a unique generation. With the guidance of Henri Tajfel’s social identity theory, the study uncovers the emergence of the Zhiqing group and the Zhiqing identity, explains individuals’ acquisitions of the Zhiqing identity and analyzes how it has kept influencing individuals’ lives during and after the UMDC Movement. Using Zhiqing’s life stories allowed the researcher to combine the historical and sociological aspects in her examination of Zhiqing’s identity issues. In each life story, the narrator reviewed his/her life experience, reflected on socio-historical changes and expressed his/her emotions and ideas about identity issues. Utilizing methods of in-depth interview and thematic analysis, the researcher completed the study and presents this thesis as one interpretation on the Zhiqing identity, which, as according the researcher’s hermeneutic stance, is open to further discussion and future research.

Development of a general internet attitude scale and internet self-efficacy scale

The measurement of users’ attitudes towards and confidence with using the Internet is an important yet poorly researched topic. Previous research has encountered issues that serve to obfuscate rather than clarify. Such issues include a lack of distinction between the terms ‘attitude’ and ‘self-efficacy’, the absence of a theoretical framework to measure each concept, and failure to follow well-established techniques for the measurement of both attitude and self-efficacy. Thus, the primary aim of this research was to develop two statistically reliable scales which independently measure attitudes towards the Internet and Internet self-efficacy. This research addressed the outlined issues by applying appropriate theoretical frameworks to each of the constructs under investigation. First, the well-known three component (affect, behaviour, cognition) model of attitudes was applied to previous Internet attitude statements. The scale was distributed to four large samples of participants. Exploratory factor analyses revealed four underlying factors in the scale: Internet Affect, Internet Exhilaration, Social Benefit of the Internet and Internet Detriment. The final scale contains 21 items, demonstrates excellent reliability and achieved excellent model fit in the confirmatory factor analysis. Second, Bandura’s (1997) model of self-efficacy was followed to develop a reliable measure of Internet self-efficacy. Data collected as part of this research suggests that there are ten main activities which individuals can carry out on the Internet. Preliminary analyses suggested that self-efficacy is confounded with previous experience; thus, individuals were invited to indicate how frequently they performed the listed Internet tasks in addition to rating their feelings of self-efficacy for each task. The scale was distributed to a sample of 841 participants. Results from the analyses suggest that the more frequently an individual performs an activity on the Internet, the higher their self-efficacy score for that activity. This suggests that frequency of use ought to be taken into account in individual’s self-efficacy scores to obtain a ‘true’ self-efficacy score for the individual. Thus, a formula was devised to incorporate participants’ previous experience of Internet tasks in their Internet self-efficacy scores. This formula was then used to obtain an overall Internet self-efficacy score for participants. Following the development of both scales, gender and age differences were explored in Internet attitudes and Internet self-efficacy scores. The analyses indicated that there were no gender differences between groups for Internet attitude or Internet self-efficacy scores. However, age group differences were identified for both attitudes and self-efficacy. Individuals aged 25-34 years achieved the highest scores on both the Internet attitude and Internet self-efficacy measures. Internet attitude and self-efficacy scores tended to decrease with age with older participants achieving lower scores on both measures than younger participants. It was also found that the more exposure individuals had to the Internet, the higher their Internet attitude and Internet self-efficacy scores. Examination of the relationship between attitude and self-efficacy found a significantly positive relationship between the two measures suggesting that the two constructs are related. Implication of such findings and directions for future research are outlined in detail in the Discussion section of this thesis.

The double bind for non-traditional families in post-primary settings; to tell or not to tell their family identity

This thesis involved researching normative family discourses which are mediated through educational settings. The traditional family, consisting of father, mother and children all living together in one house is no longer reflective of the home situation of many Irish students (Lunn and Fahey, 2011). My study problematizes the dominant discourses which reflect how family differences are managed and recognised in schools. A framework using Foucauldian post structural critical analysis traces family stratification through the organisation of institutional and interpersonal relations at micro level in four post-primary schools. Standardising procedures such as the suppression of intimate relations between and among teacher and student, as well as the linear ordering of intergenerational relations, such as teacher/student and adult/child are critiqued. Normalising discourses operate in practices such as notes home which presume two parents together. Teacher assumptions about heterosexual two-parent families make it difficult for students to be open about a family setup that is constructed as different to the rest of the schools'. The management of family difference and deficit through pastoral care structures suggests a school-based politics of family adjustment. These practices beg the question whether families are better off not telling the school about their family identity. My thesis will be of interest to educational research and educational policy because it highlights how changing demographics such as family compositions are mis-conceptualised in schools, as well as revealing the changing forms of family governance through regimes such as pastoral care. This analysis allows for the existence of, and a valuing for, alternative modes of family existence, so that future curricular and legal discourses can be challenged in the interest of equity and social justice.

Beginning primary teachers’ perspectives on becoming a teacher in the workplace: Contextual, emotional, and temporo-spatial dimensions of identity shaping

The issue, with international and national overtones, of direct relevance to the present study, relates to the shaping of beginning teachers’ identities in the workplace. As the shift from an initial teacher education programme into initial practice in schools is a period of identity change worthy of investigation, this study focuses on the transformative search by nine beginning primary teachers for their teaching identities, throughout the course of their initial year of occupational experience, post-graduation. The nine beginning teacher participants work in a variety of primary school settings, thus strengthening the representativeness of the research cohort. Privileging ‘insider’ perspectives, the research goal is to understand the complexities of lived experience from the viewpoints of the participating informants. The shaping of identity is conceived of in dimensional terms. Accordingly, a framework composed of three dimensions of beginning teacher experience is devised, namely: contextual; emotional; temporo-spatial. Data collection and analysis is informed by principles derived from sociocultural theories; activity theory; figured worlds theory; and, dialogical self theory. Individual, face-to-face semi-structured interviews, and the maintenance of solicited digital diaries, are the principal methods of data collection employed. The use of a dimensional model fragments the integrated learning experiences of beginning teachers into constituent parts for the purpose of analysis. While acknowledging that the actual journey articulated by each participant is a more complex whole than the sum of its parts, key empirically-based claims are presented as per the dimensional framework employed: contextuality; emotionality; temporo-spatiality. As a result of applying the foci of an international literature to an under-researched aspect of Irish education, this study is offered as a context-specific contribution to the knowledge base on beginning teaching. As the developmental needs of beginning teachers constitute an emerging area of intense policy focus in Ireland, this research undertaking is both relevant and timely.

Self-neglect: development and evaluation of a self-neglect (SN-37) measurement instrument

Aim: To develop and evaluate the psychometric properties of an instrument for the measurement of self-neglect (SN).Conceptual Framework: An elder self-neglect (ESN) conceptual framework guided the literature review and scale development. The framework has two key dimensions physical/psycho-social and environmental and seven sub dimensions which are representative of the factors that can contribute to intentional and unintentional SN. Methods: A descriptive cross-sectional design was adopted to achieve the research aim. The study was conducted in two phases. Phase 1 involved the development of the questionnaire content and structure. Phase 2 focused on establishing the psychometric properties of the instrument. Content validity was established by a panel of 8 experts and piloted with 9 health and social care professionals. The instrument was subsequently posted with a stamped addressed envelope to 566 health and social care professionals who met specific eligibility criteria across the four HSE areas. A total of 341 questionnaires were returned, a response rate of 60% and 305 (50%) completed responses were included in exploratory factor analysis (EFA). Item and factor analyses were performed to elicit the instruments underlying factor structure and establish preliminary construct validity. Findings: Item and factor analyses resulted in a logically coherent, 37 items, five factor solution, explaining 55.6% of the cumulative variance. The factors were labelled: ‘Environment’, ‘Social Networks’, ‘Emotional and Behavioural Liability’, ‘Health Avoidance’ and ‘Self-Determinism’. The factor loadings were >0.40 for all items on each of the five subscales. Preliminary construct validity was supported by findings. Conclusion: The main outcome of this research is a 37 item Self-Neglect (SN-37) measurement instrument that was developed by EFA and underpinned by an ESN conceptual framework. Preliminary psychometric evaluation of the instrument is promising. Future work should be directed at establishing the construct and criterion related validity of the instrument.

Morphing low-affinity ligands into high-avidity nanoparticles by thermally triggered self-assembly of a genetically encoded polymer.

Multivalency is the increase in avidity resulting from the simultaneous interaction of multiple ligands with multiple receptors. This phenomenon, seen in antibody-antigen and virus-cell membrane interactions, is useful in designing bioinspired materials for targeted delivery of drugs or imaging agents. While increased avidity offered by multivalent targeting is attractive, it can also promote nonspecific receptor interaction in nontarget tissues, reducing the effectiveness of multivalent targeting. Here, we present a thermal targeting strategy--dynamic affinity modulation (DAM)--using elastin-like polypeptide diblock copolymers (ELP(BC)s) that self-assemble from a low-affinity to high-avidity state by a tunable thermal "switch", thereby restricting activity to the desired site of action. We used an in vitro cell binding assay to investigate the effect of the thermally triggered self-assembly of these ELP(BC)s on their receptor-mediated binding and cellular uptake. The data presented herein show that (1) ligand presentation does not disrupt ELP(BC) self-assembly; (2) both multivalent ligand presentation and upregulated receptor expression are needed for receptor-mediated interaction; (3) increased size of the hydrophobic segment of the block copolymer promotes multivalent interaction with membrane receptors, potentially due to changes in the nanoscale architecture of the micelle; and (4) nanoscale presentation of the ligand is important, as presentation of the ligand by micrometer-sized aggregates of an ELP showed a low level of binding/uptake by receptor-positive cells compared to its presentation on the corona of a micelle. These data validate the concept of thermally triggered DAM and provide rational design parameters for future applications of this technology for targeted drug delivery.

Physical activity in US Blacks: a systematic review and critical examination of self-report instruments.

BACKGROUND: Physical activity self-report instruments in the US have largely been developed for and validated in White samples. Despite calls to validate existing instruments in more diverse samples, relatively few instruments have been validated in US Blacks. Emerging evidence suggests that these instruments may have differential validity in Black populations. PURPOSE: This report reviews and evaluates the validity and reliability of self-reported measures of physical activity in Blacks and makes recommendations for future directions. METHODS: A systematic literature review was conducted to identify published reports with construct or criterion validity evaluated in samples that included Blacks. Studies that reported results separately for Blacks were examined. RESULTS: The review identified 10 instruments validated in nine manuscripts. Criterion validity correlations tended to be low to moderate. No study has compared the validity of multiple instruments in a single sample of Blacks. CONCLUSION: There is a need for efforts validating self-report physical activity instruments in Blacks, particularly those evaluating the relative validity of instruments in a single sample.

Disturbance, response, and persistence in self-organized forested communities: Analysis of robustness and resilience in five communities in Southern Indiana

We develop an analytic framework for the analysis of robustness in social-ecological systems (SESs) over time. We argue that social robustness is affected by the disturbances that communities face and the way they respond to them. Using Ostrom's ontological framework for SESs, we classify the major factors influencing the disturbances and responses faced by five Indiana intentional communities over a 15-year time frame. Our empirical results indicate that operational and collective-choice rules, leadership and entrepreneurship, monitoring and sanctioning, economic values, number of users, and norms/social capital are key variables that need to be at the core of future theoretical work on robustness of self-organized systems. © 2010 by the author(s).