Critiquing Variational Theories of the Anderson-Hubbard Model: Real-Space Self-Consistent Hartree-Fock Solutions

A simple and commonly employed approximate technique with which one can examine spatially disordered systems when strong electronic correlations are present is based on the use of real-space unrestricted self-consistent Hartree-Fock wave functions. In such an approach the disorder is treated exactly while the correlations are treated approximately. In this report we critique the success of this approximation by making comparisons between such solutions and the exact wave functions for the Anderson-Hubbard model. Due to the sizes of the complete Hilbert spaces for these problems, the comparisons are restricted to small one-dimensional chains, up to ten sites, and a 4x4 two-dimensional cluster, and at 1/2 filling these Hilbert spaces contain about 63,500 and 166 million states, respectively. We have completed these calculations both at and away from 1/2 filling. This approximation is based on a variational approach which minimizes the Hartree-Fock energy, and we have completed comparisons of the exact and Hartree-Fock energies. However, in order to assess the success of this approximation in reproducing ground-state correlations we have completed comparisons of the local charge and spin correlations, including the calculation of the overlap of the Hartree-Fock wave functions with those of the exact solutions. We find that this approximation reproduces the local charge densities to quite a high accuracy, but that the local spin correlations, as represented by , are not as well represented. In addition to these comparisons, we discuss the properties of the spin degrees of freedom in the HF approximation, and where in the disorder-interaction phase diagram such physics may be important

Evaluating critiquing-based recommencler agents

We describe a user study evaluating two critiquing-based recommender agents based on three criteria: decision accuracy, decision effort, and user confidence. Results show that user-motivated critiques were more frequently applied and the example critiquing system employing only this type of critiques achieved the best results. In particular, the example critiquing agent significantly improves users' decision accuracy with less cognitive effort consumed than the dynamic critiquing recommender with system-proposed critiques. Additionally, the former is more likely to inspire users' confidence of their choice and promote their intention to purchase and return to the agent for future use. Copyright © 2006, American Association for Artificial Intelligence (www.aaai.org). All rights reserved

Responses and Influences: A Model of Online Information Use for Learning

Introduction. This paper explores the complexity of online information use for learning in the culturally diverse ICT-intensive higher education context. It presents a Model of responses and influences in online information use for learning that aims to increase awareness of the complexity of online information use and support information literacy development. Background. Despite increasing integration of information literacy into university curricula there are evident limitations in students’ use of information associated with an information literacy imbalance between well developed IT skills & uncritical approaches, compounded by differences in cultural and linguistic experience. Influences. This model draw insight from models of: information behaviour/seeking (Wilson, Foster, Kuhlthau), information literacy (Bruce), cross-cultural adaptation (Anderson), reflective online use (Hughes, Bruce & Edwards). The model. Incorporates behavioural, cognitive & affective responses with cultural & linguistic influences in an action research framework that represents online information use - envisaged as the experience of engaging with online information for learning - as holistic, dynamic and continuous. Conclusion. The model represents the synergy between information use and learning. It supports the development of inclusive reflective approaches to information literacy that address identified learning challenges related to information literacy imbalance and cultural & linguistic diversity

World-view perspectives

The foundation of a tolerant society is an ability to foster and respond to the diversity of perspective among its people. Cognitive psychologists have described how perspective influences information processing, while our innate ability to adopt perspective has been established by neuropsychology. Literature, through the use of point-of-view, together with results from researchers adopting socio-cultural paradigms suggests perspective is also a social construct. An ecologically-based framework is described that provides cohesion to the temporal, spatial, universal and other types of world-view perspective associated, predominantly, with indigenous cultures. Culturally responsible types of creative and critical thinking are evoked when world-view perspective is engaged while reading text and reading the world. World-view perspective provides us with a means of critiquing the construction of knowledge through the de-construction of dominant discourses, re-valuing of indigenous world-views and reducing the relational distance between indigenous and non-indigenous peoples