The Use of Faraday Rotation Sign Maps as a Diagnostic for Helical Jet Magnetic Fields

We present maps of the sign of the Faraday Rotation measure [sign(RM)] obtained from multi-frequency radio observations on the Very Long Baseline Array (VLBA). Many of the Active Galactic Nuclei (AGN) considered have B-field structures with a central "spine" of B-field orthogonal to the jet and/or a longitudinal B-field near one or both edges of the jet. This structure can plausibly be interpreted as being caused by a helical/toroidal jet magnetic field. Faraday Rotation is a rotation of the plane of polarization that occurs when the polarized radiation passes through a magnetized plasma. The sign of the RM is determined by the direction of the line-of-sight B-Field in the region causing the Faraday Rotation, and an ordered toroidal or helical magnetic field associated with an AGN jet will thus produce a distinctive bilateral distribution of positive and negative RMs across the jet. We present and discuss sign(RM) maps and their possible interpretation regarding the magnetic field geometries for several sources.Comment: From the proceedings of Beamed and Unbeamed Gamma-Rays from Galaxies, April 11-15, 2011, Muonio, Finland. 5 pages, 4 figure

Joyce's noises

Molly Bloom is lying restlessly in bed, her head next to her husband's feet, counting the days until she will next be with her lover, Blazes Boylan: "Thursday Friday one Saturday two Sunday three O Lord I cant wait till Monday" (Joyce, U 18.594-95).1 The next item we see on the page--one can hardly call it a word--is a bizarre string of letters: "frseeeeeeeefronnnng" (U 18.596). All in lower case, it begins the fourth of the so-called sentences of the final episode of Ulysses. Its challenge to our reading of the episode is multiple: it is unpronounceable, at least according to the norms of the English language; it is meaningless; and it is hardly conceivable as part of Molly's thought processes in the way that everything in the chapter up to this point has been. Joyce does not leave us mystified for long, however: the verbalized thoughts that follow this strange irruption explain what it is doing here: "train somewhere whistling the strength those engines have in them like big giants" (U 18.596-97). Distant train whistles may more usually evoke associations of travel, separation, nostalgia, or longing, but Molly's response is clearly colored by her active desire for the man she has just called, with obvious relish, a "savage brute" (U 18.594).Issue title: Sound Effects

“To speak of this you would need the tongue of a god”: On Representing the Trauma of Township Violence

Esse artigo trata da representação literária de traumas como os massacres urbanos na África do Sul nas obras de três autores, J.M.Coetzee, Age of Iron, André Brink’s An Act of Terror and Elsa Joubert, The Long Journey of Poppie Nongena. A comparação das respectivas técnicas narrativas coloca a questão se o autor tem, ou não, o poder e a autoridade de falar em nome do outro (oprimido)

The soldier in late Victorian society : images and ambiguities

This thesis examines effects of the Boer War (1899- 1902) on images of the soldier. The thesis argues that the trauma of the Boer War for British political culture be may explored in changes in representations of the soldier to be found in the production and reception of contemporary literary genres and popular forms. This change cannot be theorized adequately in terms of an intensification of patriotism, the development of nationalism or a crisis of imperialism. A pervasive approach, often drawing on the work of Edward Said, has as its central premise that imperial polity imposes a discourse of domination on its relacitrant Other. This approach will be found to lack the conceptual nuances needed to address the different forms of representation examined in the thesis. These different forms of representation articulate a range of responses to the repercussion of the war on the relation between the shifting external boundaries of Empire and the internal boundaries of civil society between state and civil society, civilian and military identities, class antagonisms and national projections. Changes in the image of the soldier bear the irresistable politicization as well as the contrary paradoxical burdens of the attempted pacification of those related external and internal boundaries. The thesis includes a study of a range of sources, including as yet undiscussed texts, which verify and explore further the argument that literary and popular forms and representations display the changing fault lines of political culture rather than simply present or act as vehicles for a truiumphalist and unequivocal discursive domination

Advanced mathematics and deductive reasoning skills: testing the Theory of Formal Discipline

This thesis investigates the Theory of Formal Discipline (TFD): the idea that studying mathematics develops general reasoning skills. This belief has been held since the time of Plato (2003/375B.C), and has been cited in recent policy reports (Smith, 2004; Walport, 2010) as an argument for why mathematics should hold a privileged place in the UK's National Curriculum. However, there is no rigorous research evidence that justifies the claim. The research presented in this thesis aims to address this shortcoming. Two questions are addressed in the investigation of the TFD: is studying advanced mathematics associated with development in reasoning skills, and if so, what might be the mechanism of this development? The primary type of reasoning measured is conditional inference validation (i.e. `if p then q; not p; therefore not q'). In two longitudinal studies it is shown that the conditional reasoning behaviour of mathematics students at AS level and undergraduate level does change over time, but that it does not become straightforwardly more normative. Instead, mathematics students reason more in line with the `defective' interpretation of the conditional, under which they assume p and reason about q. This leads to the assumption that not-p cases are irrelevant, which results in the rejection of two commonly-endorsed invalid inferences, but also in the rejection of the valid modus tollens inference. Mathematics students did not change in their reasoning behaviour on a thematic syllogisms task or a thematic version of the conditional inference task. Next, it is shown that mathematics students reason significantly less in line with a defective interpretation of the conditional when it is phrased `p only if q' compared to when it is phrased `if p then q', despite the two forms being logically equivalent. This suggests that their performance is determined by linguistic features rather than the underlying logic. The final two studies investigated the heuristic and algorithmic levels of Stanovich's (2009a) tri-process model of cognition as potential mechanisms of the change in conditional reasoning skills. It is shown that mathematicians' defective interpretation of the conditional stems in part from heuristic level processing and in part from effortful processing, and that the executive function skills of inhibition and shifting at the algorithmic level are correlated with its adoption. It is suggested that studying mathematics regularly exposes students to implicit `if then' statements where they are expected to assume p and reason about q, and that this encourages them to adopt a defective interpretation of conditionals. It is concluded that the TFD is not supported by the evidence; while mathematics does seem to develop abstract conditional reasoning skills, the result is not more normative reasoning

A case study in digitizing a photographic collection

This paper reviews the processes involved in the digitisation, display and storage of medium size collections of photographs using mid-range commercially available equipment. Guidelines for evaluating the performance of these digitisation processes based on aspects of image quality are provided. A collection of photographic slides, representing first-generation analogue reproductions of a photographic collection from the nineteenth century, is treated as a case study. Constraints on the final image quality and the implications of digital archiving are discussed. Full descriptions of device characterisation and calibration procedures are given and results from objective measurements carried out to assess the digitisation system are presented. The important issues of file format, physical storage and data migration are also addressed