A new population of terrestrial gamma-ray flashes in the RHESSI data

Terrestrial gamma-ray flashes (TGFs) are the most energetic photon phenomenon occurring naturally on Earth. An outstanding question is as follows: Are these flashes just a rare exotic phenomenon or are they an intrinsic part of lightning discharges and therefore occurring more frequently than previously thought? All measurements of TGFs so far have been limited by the dynamic range and sensitivity of spaceborne instruments. In this paper we show that there is a new population of weak TGFs that has not been identified by search algorithms. We use the World Wide Lightning Location Network (WWLLN) to identify lightning that occurred in 2006 and 2012 within the 800 km field of view of Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). By superposing 740,210 100 ms RHESSI data intervals, centered at the time of the WWLLN detected lightning, we identify at least 141 and probably as many as 191 weak TGFs that were not part of the second RHESSI data catalogue. This supports the suggestion that the global TGF production rate is larger than previously reported

Spotlight on role-play : interrogating the theory and practice of role-play in adult education from a theatre arts perspective

University of Technology, Sydney. Faculty of Education.This thesis addresses the use of role-play in adult education. It is a piece of scholarly research that aims to further develop ideas of theory and practice in this area. It is also hoped that this research will provide a framework for practice that will encourage both adult educators and learners to feel more confident using role-play as a learning approach. The research arose from problems that the author experienced in her practice as an adult educator using role-play in adult vocational education training programs in higher education. The key problem identified was how to involve participants in a role-play but at the same time encourage their critical awareness so that they could learn from the experience. Questions of involvement and its converse, detachment, also relate to the emotional content of learning, and how this can be safely and productively managed in a role-play situation. Role-play in adult education is an under-theorised area, and the available literature offers inadequate answers to the problems identified above. There is, however, a great deal of research and information about role-play in theatre arts and related areas such as drama-in-education and dramatherapy, but this is rarely referred to in adult education. This may be because role-play is often presented as an aspect of simulation and gaming, which are strategies that tend to adopt, a scientific rather than an arts approach to learning. Also, since much of the theatre arts literature that is relevant to role-play comes from drama-in-education, it refers to child or adolescent learning rather than adult education. This thesis argues that the positioning of role-play in the theoretical field of simulation and gaming is limiting. It proposes that it would be more productive if role-play could be seen as a theatre arts strategy. It demonstrates the significant benefits role-play could gain from an analysis of the available literature in this area, and how this could beneficially alter the way role-play is conceptualised and practised. Once role-play is positioned as a theatre arts strategy it is possible to explore how its 'significant form' engages participants, yet also enables them to remain critically detached from the role-play so they can learn from it. The thesis also presents the proposition that aesthetic learning may have something significant to offer adult education. Theatre arts can provide a comprehensive framework for conceptualsing and using role-play in adult education. If role-play were to be utilised within this framework, then adding an arts perspective to adult education could potentially transform learning in this area

Contribution of integrated farm management (IFM) to Defra objectives

A farming system comprises a complex of interrelated and interacting factors. Any study of an isolated part of the system will not provide adequate understanding of the behaviour of the entire system and interactions may be equally or more important than individual components. There is therefore a requirement for the development of integrated approaches and practices to help farming systems adapt to, eliminate or reduce the negative impacts of production on the environment. This must be achieved whilst maintaining the economic viability of the farm enterprise. Our analysis has confirmed that IFM techniques generally have far more beneficial than adverse effects on current Defra policy objectives. However, there are some notable ‘conflicts’ where a technique that has a large beneficial effect in one policy area has a large negative effect in another. Carbon footprinting is used to quantify the impact of some integrated farming practices

Pattern formation by lateral inhibition with feedback: a mathematical model of Delta-Notch intercellular signalling

In many developing tissues, adjacent cells diverge in character so as to create a fine-grained pattern of cells in contrasting states of differentiation. It has been proposed that such patterns can be generated through lateral inhibition—a type cells–cell interaction whereby a cell that adopts a particular fate inhibits its immediate neighbours from doing likewise. Lateral inhibition is well documented in flies, worms and vertebrates. In all of these organisms, the transmembrane proteins Notch and Delta (or their homologues) have been identified as mediators of the interaction—Notch as receptor, Delta as its ligand on adjacent cells. However, it is not clear under precisely what conditions the Delta-Notch mechanism of lateral inhibition can generate the observed types of pattern, or indeed whether this mechanism is capable of generating such patterns by itself. Here we construct and analyse a simple and general mathematical model of such contact-mediated lateral inhibition. In accordance with experimental data, the model postulates that receipt of inhibition (i.e. activation of Notch) diminishes the ability to deliver inhibition (i.e. to produce active Delta). This gives rise to a feedback loop that can amplify differences between adjacent cells. We investigate the pattern-forming potential and temporal behavior of this model both analytically and through numerical simulation. Inhomogeneities are self-amplifying and develop without need of any other machinery, provided the feedback is sufficiently strong. For a wide range of initial and boundary conditions, the model generates fine-grained patterns similar to those observed in living systems

Base-modified GDP-mannose derivatives and their substrate activity towards a yeast mannosyltransferase

We have previously developed a new class of inhibitors and chemical probes for glycosyltransferases through base-modification of the sugar-nucleotide donor. The key feature of these donor analogues is the presence of an additional substituent at the nucleobase. To date, the application of this general concept has been limited to UDP-sugars and UDP-sugar-dependent glycosyltransferases. Herein, we report for the first time the application of our approach to a GDP-mannose-dependent mannosyltransferase. We have prepared four GDP-mannose derivatives with an additional substituent at either position 6 or 8 of the nucleobase. These donor analogues were recognised as donor substrates by the mannosyltransferase Kre2p from yeast, albeit with significantly lower turnover rates than the natural donor GDP-mannose. The presence of the additional substituent also redirected enzyme activity from glycosyl transfer to donor hydrolysis. Taken together, our results suggest that modification of the donor nucleobase is, in principle, a viable strategy for probe and inhibitor development against GDP-mannose-dependent GTs

Estimating the masses of extra-solar planets

All extra-solar planet masses that have been derived spectroscopically are lower limits since the inclination of the orbit to our line-of-sight is unknown except for transiting systems. It is, however, possible to determine the inclination angle, i, between the rotation axis of a star and an observer's line-of-sight from measurements of the projected equatorial velocity (v sin i), the stellar rotation period (P_rot) and the stellar radius (R_star). This allows the removal of the sin i dependency of spectroscopically derived extra-solar planet masses under the assumption that the planetary orbits lie perpendicular to the stellar rotation axis. We have carried out an extensive literature search and present a catalogue of v sin i, P_rot, and R_star estimates for exoplanet host stars. In addition, we have used Hipparcos parallaxes and the Barnes-Evans relationship to further supplement the R_star estimates obtained from the literature. Using this catalogue, we have obtained sin i estimates using a Markov-chain Monte Carlo analysis. This allows proper 1-sigma two-tailed confidence limits to be placed on the derived sin i's along with the transit probability for each planet to be determined. While a small proportion of systems yield sin i's significantly greater than 1, most likely due to poor P_rot estimations, the large majority are acceptable. We are further encouraged by the cases where we have data on transiting systems, as the technique indicates inclinations of ~90 degrees and high transit probabilities. In total, we estimate the true masses of 133 extra-solar planets. Of these, only 6 have revised masses that place them above the 13 Jupiter mass deuterium burning limit. Our work reveals a population of high-mass planets with low eccentricities and we speculate that these may represent the signature of different planetary formation mechanisms at work.Comment: 40 pages, 6 tables, 2 figures. Accepted for publication in the Monthly Notices of the Royal Astronomical Society after editing of Tables 1 & 6 for electronic publication. Html abstract shortened for astro-ph submissio

A search for starlight reflected from HD 75289 b

We have used a doppler tomographic analysis to conduct a deep search for the starlight reflected from the planetary companion to HD 75289. In 4 nights on VLT2/UVES in January 2003, we obtained 684 high resolution echelle spectra with a total integration time of 26 hours. We establish an upper limit on the planet's geometric albedo p < 0.12 (to the 99.9% significance level) at the most probable orbital inclination i ~ 60 degrees, assuming a grey albedo, a Venus-like phase function and a planetary radius R_p = 1.6 R_Jup. We are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks.Comment: 5 pages, 5 figures, MNRAS accepted 12 Oct 200

Mentoring First-Year Distance Education Students in Taxation Studies

Research indicates that the dropout rate for fi rst-year students in universities is traditionally higher than for later years,1 with external or distance students posing the highest risk of withdrawal from studies of any group.2 This has been the case with the Bachelor of Taxation (BTax) in the Australian School of Taxation (Atax), Faculty of Law at the University of New South Wales (UNSW). The BTax program is offered nationally in an off-campus delivery mode and focuses on teaching taxation and commercial law as well as economics and accounting. The majority of its students are in fulltime employment, studying part-time; and generally students are in their late 20s to early 40s. A range of support measures, including student peer mentoring, has been successfully employed in Australia and elsewhere as a strategy to support fi rst-year university students in their studies