Discharge-generated electrical fields and electrical tree structures

The discharge-avalanche (D-A) model for electrical tree propagation in polymers is founded entirely upon basic physical concepts. Electrical discharges in an existing tree structure are taken to raise the electrical field in the polymer both along the discharge path and particularly at the tree tips. As a result of the field increase, electron multiplication avalanches occur within the polymer causing damage, possibly through ionisation of polymer molecules, which is accumulated over a period of thousands (or more) cycles and eventually leads to a tree extension of limited size. The assumption that the damage produced in an avalanche is proportional to the number of ionisations allows the model to be expressed quantitatively in terms of material properties: such as the ionisation potential, I; the impact-ionisation length parameter λ; the critical number of ionisations for tree extension Nc; discharge features such as the number of 1-electron initiated avalanches per half cycle, Nb ; and the potential difference ΔV between the start and end of the avalanche over a distance Lb

Is the cosmic microwave background really non-Gaussian?

Two recent papers have claimed detection of non-Gaussian features in the COBE DMR sky maps of the cosmic microwave background. We confirm these results, but argue that Gaussianity is still not convincingly ruled out. Since a score of non-Gaussianity tests have now been published, one might expect some mildly significant results even by chance. Moreover, in the case of one measure which yields a detection, a bispectrum statistic, we find that if the non-Gaussian feature is real, it may well be due to detector noise rather than a non-Gaussian sky signal, since a signal-to-noise analysis localizes it to angular scales smaller than the beam. We study its spatial origin in case it is nonetheless due to a sky signal (eg, a cosmic string wake or flat-spectrum foreground contaminant). It appears highly localized in the direction b=39.5, l=257, since removing a mere 5 pixels inside a single COBE beam area centered there makes the effect statistically insignificant. We also test Guassianity with an eigenmode analysis which allows a sky map to be treated as a random number generator. A battery of tests of this generator all yield results consistent with Gaussianity.Comment: Revised to match accepted ApJL version. 4 pages with 2 figs included. Links and color fig at http://www.sns.ias.edu/~max/gaussianity_frames.html or from [email protected]

Investigative Journalism and Human Rights

The early years of the twenty-first century may have brought a renewed global impetus to investigative journalism’s concern with human rights. Founded in normative views of journalism as a social watchdog, and the specificities of its investigative turn as combative and challenging, investigative journalism has been intimately connected with the recognition, promotion and protection of human rights over more than two centuries. The waxing of investigative journalism appears to occur when social disruption coincides with enhanced communication capabilities – from the early throes of modernisation to current processes of democratisation, globalisation and digitisation. Investigative journalism acts as a form of social conscience, exposing lapses in a commitment to human rights. At the same time, investigative journalism lays claim to its own right to freedom of expression

A socially-responsible educational response to routine-biased technological change in journalism: Fostering employability among journalists in the United Kingdom

Journalism in the UK straddles the divide between high- and middle-skilled employment. Since the 1970s those determined to be middle-skilled have been vulnerable to increasing difficulty in finding employment, deepening insecurity of employment and limited opportunities for advancement as work has been routinized and off-shored. This is especially so for young people. Moreover, journalism is also a short-term career. However, at the same time, journalism has significantly upskilled through graduatisation, and currently the most favoured route into journalism is through a postgraduate taught (PGT) qualification, such as a Master’s degree. This study examines the career experiences of 889 alumni of a PGT newspaper journalism course and maps them to employment trends. It is argued that the socially responsible approach is to prepare alumni for life during and after journalism through the development of their employability, rather than focusing on their immediate employment prospects

JetWeb: A WWW Interface and Database for Monte Carlo Tuning and Validation

A World Wide Web interface to a Monte Carlo validation and tuning facility is described. The aim of the package is to allow rapid and reproducible comparisons to be made between detailed measurements at high-energy physics colliders and general physics simulation packages. The package includes a relational database, a Java servlet query and display facility, and clean interfaces to simulation packages and their parameters.Comment: See http://jetweb.hep.ucl.ac.uk for further informatio

Notes on Texas robber flies with the description of a new species of Proctacanthella (Asilidae: Diptera)

http://deepblue.lib.umich.edu/bitstream/2027.42/56743/1/OP304.pd