A search for 21 cm HI absorption in AT20G compact radio galaxies

We present results from a search for 21 cm associated HI absorption in a sample of 29 radio sources selected from the Australia Telescope 20 GHz survey. Observations were conducted using the Australia Telescope Compact Array Broadband Backend, with which we can simultaneously look for 21 cm absorption in a redshift range of 0.04 < z < 0.08, with a velocity resolution of 7 km/s . In preparation for future large-scale H I absorption surveys we test a spectral-line finding method based on Bayesian inference. We use this to assign significance to our detections and to determine the best-fitting number of spectral-line components. We find that the automated spectral-line search is limited by residuals in the continuum, both from the band-pass calibration and spectral-ripple subtraction, at spectral-line widths of \Deltav_FWHM > 103 km/s . Using this technique we detect two new absorbers and a third, previously known, yielding a 10 per cent detection rate. Of the detections, the spectral-line profiles are consistent with the theory that we are seeing different orientations of the absorbing gas, in both the host galaxy and circumnuclear disc, with respect to our line-of-sight to the source. In order to spatially resolve the spectral-line components in the two new detections, and so verify this conclusion, we require further high-resolution 21 cm observations (~0.01 arcsec) using very long baseline interferometry.Comment: 16 pages, 8 figures and 5 tables; accepted for publication in MNRAS (version 2 based on proof corrections

The Structure of the [Zn_In - V_P] Defect Complex in Zn Doped InP

We study the structure, the formation and binding energies and the transfer levels of the zinc-phosphorus vacancy complex [Zn_In - V_P] in Zn doped p-type InP, as a function of the charge, using plane wave ab initio DFT-LDA calculations in a 64 atom supercell. We find a binding energy of 0.39 eV for the complex, which is neutral in p-type material, the 0/-1 transfer level lying 0.50 eV above the valence band edge, all in agreement with recent positron annihilation experiments. This indicates that, whilst the formation of phosphorus vacancies (V_P) may be involved in carrier compensation in heavily Zn doped material, the formation of Zn-vacancy complexes is not. Regarding the structure: for charge states Q=+6 to -4 the Zn atom is in an sp^2 bonded DX position and electrons added/removed go to/come from the remaining dangling bonds on the triangle of In atoms. This reduces the effective vacancy volume monatonically as electrons are added to the complex, also in agreement with experiment. The reduction occurs through a combination of increased In-In bonding and increased Zn-In electrostatic attraction. In addition, for certain charge states we find complex Jahn-Teller behaviour in which up to three different structures, (with the In triangle dimerised, antidimerised or symmetric) are stable and are close to degenerate. We are able to predict and successfully explain the structural behaviour of this complex using a simple tight binding model.Comment: 10 pages text (postscript) plus 8 figures (jpeg). Submitted to Phys. Rev.

Multiple electron pumping

The need to pump single electrons with a high degree of accuracy and fidelity has led to the development of a range of different pump and turnstile designs. Previous pumping mechanisms have all demonstrated that pumping more than one electron per cycle degrades the quantisation of the measured current. This unreliable delivery of multiple electrons per cycle has limited the use of on-demand single electron sources in electron quantum optic experiments. We present highly quantised current with multiple electrons pumped per cycle. We experimentally demonstrate that in our pumps an increase in electron throughput per cycle does not lead to an appreciable degradation in the accuracy of the produced current. Our pump is realised in an aluminium gallium arsenide two-dimensional electron gas, where electrons are pumped through a one-dimensional split-gate confinement potential under the influence of an applied source-drain voltage VSD , and where the pump is driven by a trapezoidal arbitrary waveform. This combination of a split-gate potential, VSD bias and trapezoidal wave form has led to the observation of robust quantised plateaus where not just a single electron, but a multiple integer number of electrons are pumped per cycle with a high degree of robustness and without the need of a magnetic field. For seven electrons per cycle, we report an increase of over two orders of magnitude in pumping accuracy from 2.72 × 10 − 2 in devices operating in the conventional pumping regime, to 1.64 × 10 − 4 in pumps operating in what we call the long plateau regime, a regime accessed under a change in a split-gate pumps applied VSD voltage. This pump will find direct use in quantum transport measurements where the metrological accuracy of single electrons pumped per cycle is not required and the low throughput per cycle of electrons is limiting

Increased rates of large-magnitude explosive eruptions in Japan in the late Neogene and Quaternary

Tephra layers in marine sediment cores from scientific ocean drilling largely record high-magnitude silicic explosive eruptions in the Japan arc for up to the last 20 million years. Analysis of the thickness variation with distance of 180 tephra layers from a global dataset suggests that the majority of the visible tephra layers used in this study are the products of caldera-forming eruptions with magnitude (M) &gt;6, considering their distances at the respective drilling sites to their likely volcanic sources. Frequency of visible tephra layers in cores indicates a marked increase in rates of large magnitude explosive eruptions at ~8 Ma, 6–4 Ma and further increase after ~2 Ma. These changes are attributed to major changes in tectonic plate interactions. Lower rates of large magnitude explosive volcanism in the Miocene are related to a strike-slip dominated boundary (and temporary cessation or deceleration of subduction) between the Philippine Sea Plate and southwest Japan, combined with the possibility that much of the arc in northern Japan was submerged beneath sea level partly due to previous tectonic extension of Northern Honshu related to formation of the Sea of Japan. Changes in plate motions and subduction dynamics during the ~8 Ma to present period led to (1) increased arc-normal subduction in southwest Japan (and resumption of arc volcanism) and (2) shift from extension to compression of the upper plate in northeast Japan, leading to uplift, crustal thickening and favourable conditions for accumulation of the large volumes of silicic magma needed for explosive caldera-forming eruptions

Tales from the playing field: black and minority ethnic students' experiences of physical education teacher education

This article presents findings from recent research exploring black and minority ethnic (BME) students’ experiences of Physical Education teacher education (PETE) in England (Flintoff, 2008). Despite policy initiatives to increase the ethnic diversity of teacher education cohorts, BME students are under-represented in PETE, making up just 2.94% of the 2007/8 national cohort, the year in which this research was conducted. Drawing on in-depth interviews and questionnaires with 25 BME students in PETE, the study sought to contribute to our limited knowledge and understanding of racial and ethnic difference in PE, and to show how ‘race,’ ethnicity and gender are interwoven in individuals’ embodied, everyday experiences of learning how to teach. In the article, two narratives in the form of fictional stories are used to present the findings. I suggest that narratives can be useful for engaging with the experiences of those previously silenced or ignored within Physical Education (PE); they are also designed to provoke an emotional as well as an intellectual response in the reader. Given that teacher education is a place where we should be engaging students, emotionally and politically, to think deeply about teaching, education and social justice and their place within these, I suggest that such stories of difference might have a useful place within a critical PETE pedagogy

On Passion and Sports Fans:A Look at Football

The purpose of the present research was to test the applicability of the Dualistic Model of Passion (Vallerand et al., 2003) to being a sport (football) fan. The model posits that passion is a strong inclination toward an activity that individuals like (or even love), that they value, and in which they invest time and energy. Furthermore, two types of passion are proposed: harmonious and obsessive passion. While obsessive passion entails an uncontrollable urge to engage in the passionate activity, harmonious passion entails a sense of volition while engaging in the activity. Finally, the model posits that harmonious passion leads to more adaptive outcomes than obsessive passion. Three studies provided support for this dualistic conceptualization of passion. Study 1 showed that harmonious passion was positively associated with adaptive behaviours (e.g., celebrate the team’s victory), while obsessive passion was rather positively associated with maladaptive behaviours (e.g., to risk losing one’s employment to go to the team’s game). Study 2 used a short Passion Scale and showed that harmonious passion was positively related to the positive affective life of fans during the 2006 FIFA World Cup, psychological health (self-esteem and life satisfaction), and public displays of adaptive behaviours (e.g., celebrating one’s team victory in the streets), while obsessive passion was predictive of maladaptive affective life (e.g., hating opposing team’s fans) and behaviours (e.g., mocking the opposing team’s fans). Finally, Study 3 examined the role of obsessive passion as a predictor of partner’s conflict that in turn undermined partner’s relationship satisfaction. Overall, the present results provided support for the Dualistic Model of Passion. The conceptual and applied implications of the findings are discussed

Transforming teacher education, an activity theory analysis

This paper explores the work of teacher education in England and Scotland. It seeks to locate this work within conflicting socio-cultural views of professional practice and academic work. Drawing on an activity theory framework that integrates the analysis of these contradictory discourses with a study of teacher educators’ practical activities, including the material artefacts that mediate the work, the paper offers a critical perspective on the social organisation of university-based teacher education. Informed by Engeström’s activity theory concept of transformation, the paper extends the discussion of contradictions in teacher education to consider the wider socio-cultural relations of the work. The findings raise important questions about the way in which teacher education work within universities is organised and the division of labour between schools and universities

Crossing borders: new teachers co-constructing professional identity in performative times

This paper draws on a range of theoretical perspectives on the construction of new teachers’ professional identity. It focuses particularly on the impact of the development in many national education systems of a performative culture of the management and regulation of teachers’ work. Whilst the role of interactions with professional colleagues and school managers in the performative school has been extensively researched, less attention has been paid to new teachers’ interactions with students. This paper highlights the need for further research focusing on the process of identity co-construction with students. A key theoretical concept employed is that of liminality, the space within which identities are in transition as teachers adjust to the culture of a new professional workplace, and the nature of the engagement of new teachers, or teachers who change schools, with students. The authors argue that an investigation into the processes of this co-construction of identity offers scope for new insights into the extent to which teachers might construct either a teacher identity at odds with their personal and professional values, or a more ‘authentic’ identity that counters performative discourses. These insights will in turn add to our understanding of the complex range of factors impacting on teacher resilience and motivation