Mediators of Inequity: Online Literate Activity in Two Eighth Grade English Language Arts Classes

This comparative case study, framed by Cultural Historical Activity Theory and sociocultural understandings of literacy, investigated students’ online literate activity in two eighth grade English Language Arts classes taught by the same teacher - one with a scripted literacy curriculum and the other without. During a year-long research project, we used ethnographic methods to explore the nature of middle school students’ literate activity in each of these classes, with particular attention to the mediators evident as students engaged in online literate activity. Specifically, this article addresses the following research question: What mediators were evident within and across each of the classes and how did these mediators influence students’ online literate activity? In addressing this question, we illustrate how particular configurations of mediators – even those operating within the context of the same school and same teacher – significantly influenced the nature of students’ online literate activity and the literate identities available to students. This study reinforces the importance of attending to the influence of offline mediators in school settings. Without such attention, students’ formal education is likely to be transferred online rather than transformed online

A security architecture for personal networks

Abstract Personal Network (PN) is a new concept utilizing pervasive computing to meet the needs of the user. As PNs edge closer towards reality, security becomes an important concern since any vulnerability in the system will limit its practical use. In this paper we introduce a security architecture designed for PNs. Our aim is to use secure but lightweight mechanisms suitable for resource constrained devices and wireless communication. We support pair-wise keys for secure cluster formation and use group keys for securing intra-cluster communication. In order to analyze the performance of our proposed mechanisms, we carry out simulations using ns-2. The results show that our mechanisms have a low overhead in terms of delay and energy consumption

Photodisintegration of light nuclei for testing a correlated realistic interaction in the continuum

An exact calculation of the photodisintegration cross section of 3H, 3He and 4He is performed using as interaction the correlated Argonne V18 potential, constructed within the Unitary Correlation Operator Method (VUCOM). Calculations are carried out using the Lorentz Integral Transform method in conjunction with an hyperspherical harmonics basis expansion. A comparison with other realistic potentials and with available experimental data is discussed. The VUCOM potential leads to a very similar description of the cross section as the Argonne V18 interaction with the inclusion of the Urbana IX three-body force for photon energies 45< w < 120 MeV, while larger differences are found close to threshold.Comment: 9 pages, 6 figure

On the structure of symmetric self-dual Lie algebras

A finite-dimensional Lie algebra is called (symmetric) self-dual, if it possesses an invariant nondegenerate (symmetric) bilinear form. Symmetric self-dual Lie algebras have been studied by Medina and Revoy, who have proven a very useful theorem about their structure. In this paper we prove a refinement of their theorem which has wide applicability in Conformal Field Theory, where symmetric self-dual Lie algebras start to play an important role due to the fact that they are precisely the Lie algebras which admit a Sugawara construction. We also prove a few corollaries which are important in Conformal Field Theory. (This paper provides mathematical details of results used, but only sketched, in the companion paper hep-th/9506151.)Comment: 19 pages, .dvi.uu (needs AMSFonts 2.1+