Sparse block-Jacobi matrices with arbitrarily accurate Hausdorff dimension

We show that the Hausdorff dimension of the spectral measure of a class of deterministic, i.e. nonrandom, block-Jacobi matrices may be determined with any degree of precision, improving a result of Zlatos [Andrej Zlatos,. Sparse potentials with fractional Hausdorff dimension, J. Funct. Anal. 207 (2004) 216-252]. (C) 2010 Elsevier Inc. All rights reserved.

Sparse 1D discrete Dirac operators I: Quantum transport

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anderson-like Transition for a Class of Random Sparse Models in d >= 2 Dimensions

We show that the Kronecker sum of d >= 2 copies of a random one-dimensional sparse model displays a spectral transition of the type predicted by Anderson, from absolutely continuous around the center of the band to pure point around the boundaries. Possible applications to physics and open problems are discussed briefly.

Virtual vignettes and pedagogical potentials : Insights into a virtual schooling service

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Dancing the Thesis : Potentials and Pitfalls in Practice-led Research

Practice-led or multi modal theses (describing examinable outcomes of postgraduate study which comprise the practice of dancing/choreography with an accompanying exegesis) are an emerging strength of dance scholarship; a form of enquiry that has been gaining momentum for over a decade, particularly in Australia and the United Kingdom. It has been strongly argued that, in this form of research, legitimate claims to new knowledge are embodied predominantly within the practice itself (Pakes, 2003) and that these findings are emergent, contingent and often interstitial, contained within both the material form of the practice and in the symbolic languages surrounding the form. In a recent study on ‘dancing’ theses Phillips, Stock, Vincs (2009) found that there was general agreement from academics and artists that ‘there could be more flexibility in matching written language with conceptual thought expressed in practice’. The authors discuss how the seemingly intangible nature of danced / embodied research, reliant on what Melrose (2003) terms ‘performance mastery’ by the ‘expert practitioner’ (2006, Point 4) involving ‘expert’ intuition (2006, Point 5), might be accessed, articulated and validated in terms of alternative ways of knowing through exploring an ongoing dialogue in which the danced practice develops emergent theory. They also propose ways in which the danced thesis can be ‘converted’ into the required ‘durable’ artefact which the ephemerality of live performance denies, drawing on the work of Rye’s ‘multi-view’ digital record (2003) and Stapleton’s ‘multi-voiced audio visual document’(2006, 82). Building on a two-year research project (2007-2008) Dancing Between Diversity and Consistency: Refining Assessment in Postgraduate Degrees in Dance, which examined such issues in relation to assessment in an Australian context, the three researchers have further explored issues around interdisciplinarity, cultural differences and documentation through engaging with the following questions:  How do we represent research in which understandings, meanings and findings are situated within the body of the dancer/choreographer?  Do these need a form of ‘translating’ into textual form in order to be accessed as research?  What kind of language structures can be developed to effect this translation: metaphor, allusion, symbol?  How important is contextualising the creative practice?  How do we incorporate differing cultural inflections and practices into our reading and evaluation?  What kind of layered documentation can assist in producing a ‘durable’ research artefact from a non-reproduce-able live event?

Experimental and theoretical studies of the redox potentials of cyclic nitroxides

The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrrolidine, piperidine, isoindoline, and azaphenalene) were determined experimentally by cyclic voltammetry in acetonitrile, and also via high-level ab initio molecular orbital calculations. It is shown that the potentials are influenced by the type of ring system, ring substituents and/or groups surrounding the radical moiety. For the pyrrolidine, piperidine, and isoindolines there is excellent agreement (mean absolute deviation of 0.05 V) between the calculated and experimental oxidation potentials; for the azaphenalenes, however, there is an extraordinary discrepancy (mean absolute deviation of 0.60 V), implying that their one-electron oxidation might involve additional processes not considered in the theoretical calculations. This recently developed azaphenalene class of nitroxide represents a new variant of a nitroxide ring fused to an aromatic system and details of the synthesis of five derivatives involving differing aryl substitution are also presented.

The potentials of student initiated netspeak in a middle primary science-inspired mutliliteracies project

There is no denying that the information technology revolution of the late twentieth century has arrived. Whilst not equitably accessible for many, others hold high expectations for the contributions online activity will make to student learning outcomes. Concurrently, and not necessarily consequentially, the number of science and technology secondary school and university graduates throughout the world has declined substantially, as has their motivation and engagement with school science (OECD, 2006). The aim of this research paper is to explore one aspect of online activity, that of forum-based netspeak (Crystal, 2006), in relation to the possibilities and challenges it provides for forms of scientific learning. This paper reports findings from a study investigating student initiated netspeak in a science inspired multiliteracies (New London Group, 2000) project in one middle primary (aged 7-10 years) multi-age Australian classroom. Drawing on the theoretical description of the Five phases of enquiry proposed by Bybee (1997), an analytic framework is proffered that allows identification of student engagement, exploration, explanation, elaboration and evaluation of scientific enquiry. The findings provide insight into online forums for advancing learning in and motivation for science in the middle primary years.

Greenhouse Gas Fluxes in Tropical and Temperae Agriculture: The Need for a Full-Cost Accounting of Global Warming Potentials

Agriculture's contribution to radiative forcing is principally through its historical release of carbon in soil and vegetation to the atmosphere and through its contemporary release of nitrous oxide (N2O) and methane (CHM4). The sequestration of soil carbon in soils now depleted in soil organic matter is a well-known strategy for mitigating the buildup of CO2 in the atmosphere. Less well-recognized are other mitigation potentials. A full-cost accounting of the effects of agriculture on greenhouse gas emissions is necessary to quantify the relative importance of all mitigation options. Such an analysis shows nitrogen fertilizer, agricultural liming, fuel use, N2O emissions, and CH4 fluxes to have additional significant potential for mitigation. By evaluating all sources in terms of their global warming potential it becomes possible to directly evaluate greenhouse policy options for agriculture. A comparison of temperate and tropical systems illustrates some of these options.