Appearance of Saturn's F ring azimuthal channels for the anti-alignment configuration between the ring and Prometheus

In this article we explore the aspect of the F ring with respect to the anti-alignment configuration between the ring and Prometheus. We focus our attention on the shape of the F ring's azimuthal channels which were first reported by Porco et al. (2005) and numerically explored by Murray et al. (2005), who found excellent agreement between Cassini's ISS reprojected images and their numerical model via a direct comparison. We find that for anti-alignment the channels are wider and go deeper inside the ring material. From our numerical model we find a new feature, an island in the middle of the channel. This island is made up of the particles that have been perturbed the most by Prometheus and only appears when this satellite is close to apoapsis. In addition, plots of the anti-alignment configuration for different orbital stages of Prometheus are obtained and discussed here.Comment: Number of pages: 12, number of tables: 1, number of figures:

Book review: nuclear energy: what everyone needs to know

Reviewing nuclear energy and disentangling myth from reality is essential to informing public opinion and policy making, and this accessible text provides a useful basis for assessing the risks, costs and benefits, finds Murray Collins

Writing Center as Contact Zone: Resources for Mediation

When ESL writers write, they are attempting to be heard in an academic community. One of the academy’s shortcomings is its disinclination to hear from writers who struggle with academic discourse. In a contact zone, such as a university that includes accomplished and novice academics, communication becomes a casualty (particularly with novices whose first language is not English). If writing centers and their staffs are the cultural mediators of this contact zone, then we must first be afforded the tools to do our work: a good text, skilled teachers, sufficient funding, and an un-marginalized place on the campus. Irrespective of these resources, however, writing consultants can provide ESL writers with knowledge of contrastive rhetorics and how a failure to acculturate to demands for standard American academic writing may limit their success at the university level.University Writing Cente

Existence, mixing and approximation of invariant densities for expanding maps on Rr

This paper generalises Gora and Boyarsky’s bounded variation(BV) approach to the ergodic properties of expanding transformations, and analysies the convergence of Ulam’s method for the numerical approximation of absolutely continuous invariant measures. We first prove an existence theorem for BV invariant densities for piecewise expanding maps on subsets of Rr; the maps must be C2, but may have infinitely many branches and need not be Markov. Under and additional “onto” assumption, explicit bounds on the spectral gap in the associated Perron-Frobenius operator are proved. The corresponding contraction rates are in the BV norm, rather than a projective metric. With this quantitative information, we are then able to prove convergence and explicit upper bounds on the approximation error in Ulam’s method for approximating invariant measures. Because the BV approach is rather concete, the methods of this paper can be applied in practice; this is illustrated by an application of the main results to the Jacobi-Perron transformation on R2

Characterisation of inflorescence development in Zea mays with four developmental mutants : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biological Science at Massey University, Palmerston North, New Zealand

The genetic control of inflorescence development has been studied in great detail in the model dicotyledonous plants Arabidopsis thaliana and Antirrhinum majus. In contrast, little is known about the genetic regulation in monocotyledonous species. Using maize (Zea mays) as a model system, the phenotypes were documented for the branched silkless1 (bd1) and ramosa (ra1, ra2, and ra3) inflorescence mutants that are characterised by abnormally branched ears. A comparison of the adult morphology and developing inflorescences using scanning electron microscopy in mutant and normal maize reveals that there are at least five reproductive meristems that can be identified in maize: the inflorescence meristem, the branch meristem, the spikelet pair meristem, the spikelet meristem, and the floret meristem. The abnormal branching in bd1 and the three-ramosa mutations is the result of the failure to determine the fate of specific types of reproductive meristems in both tassels and ears. Both RA1 and RA3 are required for the determination of spikelet pair development in branch primordia. RA2 is necessary for determinate growth in spikelet pair meristems. BD1 is required determinate growth of spikelet meristems by specifying a determinate floral meristem identity. The classification of the different types of reproductive meristems and the genes that regulate their development is essential to understanding the genetic programs that underlie inflorescence morphogenesis in maize and other Gramineae

Community business in Scotland: an alternative vision of 'enterprise culture', 1979-97

Abstract The force and coherency with which Margaret Thatcher and her inner circle outlined their vision for ‘enterprise culture’, like so many aspects of Thatcherism, have masked the complexity of its origins and the histories of alternative responses. This article provides a history of an alternative vision for enterprise culture by examining the community business movement in Scotland, the largest experiment of its kind in the UK in the 1980s and a forerunner of social enterprise. Working across Scotland, but with a hub of activity in the Strathclyde region, practitioners worked with local people to find ways to develop their neighbourhood economy while improving their environment, creating jobs, and developing services needed in their area. This article outlines the origins of the movement, the shared values of its founding members, and how their training in community development informed the community business model. It analyses how practitioners put their ideas into practice and the reasons behind the fragmentation of the movement in the 1990s. It argues that although at face value the concept of community business may appear to chime with the dominant political rhetoric of Thatcher’s ‘enterprise culture’, the history of the movement provides a signpost to an alternative, if unrealised, vision for Scotland’s recovery from social and economic depression. Where previous historical research has focused on the political consequences of Thatcher’s policies in Scotland, this research connects this discussion to the transformation of Scotland’s civic society in the wake of deindustrialization.</jats:p

Overview of Deeply Virtual Compton Scattering at HERMES

Deeply Virtual Compton Scattering represents the best experimental channel through which to understand Generalised Parton Distributions. The HERMES experiment measured the most diverse set of DVCS results of any experiment; this talk discusses the most recent sets of DVCS results released by HERMES and the unique experimental conditions found at HERMES that facilitated the measurements. We also examine the various ways in which the HERMES experimental measurements are being used to constrain GPDs and how future experiments can learn from the HERMES program.Comment: 4 pages, 2 figures, prepared for DIS201