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An introduction is presented in which the editor discusses various reports within the issue on topics including computer-supported collaborative learning, technological artifacts and Web applications.

The Second Information Technology in Education Study (SITES) 2006 results reveal that principals' perceived presence of lifelong learning-related pedagogical activities in their schools had changed markedly since the same data was collected in 1998 in SITES-M1. More intriguing was the fact that the directions of the changes were quite different depending on the education systems concerned - many of the Asian countries reported very high increases while some of the European countries reported large drops over the same 8-year period. This paper reports statistical evidence that the observed 'pendulum swing' reflects actual changes in teaching practices in these countries. Exploratory multilevel analyses results consistently show that national means of principals' vision can be used as a system-level indicator predicting national means of pedagogical orientations in schools several years later. These findings also indicate the possibility of the 'pendulum effect' being a consequence of system-level policy differences in the countries participating in the two SITES studies. [ABSTRACT FROM AUTHOR]

Microbial bioreduction of radionuclides has been the subject of much recent interest, in particular as a method for the in situ bioremediation of uranium contaminated sites. However, there have been very few studies investigating the microbially mediated redox transformations of plutonium. The redox chemistry of Pu is complicated, but the dominant environmental oxidation state is insoluble Pu(IV). However, microbial reduction of Pu(IV) to more soluble Pu(III) may enhance migration of Pu in the environment. In this study we investigated the effect of two model metal-reducing bacteria, Geobacter sulfurreducens and Shewanella oneidensis, on the redox speciation of Pu. Our results show that in all cases, the presence of bacterial cells enhanced removal of Pu from solution. UV/Visible spectra of cells and precipitates formed (dissolved in 1 M HCl), showed that the sorbed and precipitated Pu was mainly Pu(IV), but Pu(III) was also present. The results suggest that the mechanism of interaction between Pu(IV) and the two microorganisms is initial sorption to the cell surface, followed by slow reduction. Although both bacteria could reduce Pu(IV) to Pu(III), there was no increase in the solution concentrations of Pu. This suggests that the potential reduction of sorbed Pu(IV) in sediments that have been stimulated to bioremediate U(VI) may not result in problematic mobilization of Pu(III). [ABSTRACT FROM AUTHOR]

This paper describes the rationale, conceptualization and design of the Second International Information Technology in Education Study (SITES). SITES is a survey of schools and teachers of their pedagogical practices, their use of ICT and their readiness for changing their teaching–learning towards the demands of the 21st century. The study will take place under the auspices of the International Association for the Evaluation of Educational Achievement (IEA) and the data collection is planned for 2006; therefore the project is called ‘SITES2006’. [ABSTRACT FROM AUTHOR]

An image segmentation algorithm based on adaptive fuzzy c-means (FCM) clustering is presented in this paper. In the conventional FCM clustering algorithm, cluster assignment is based solely on the distribution of pixel attributes in the feature space, and does not take into consideration the spatial distribution of pixels in an image. By introducing a novel dissimilarity index in the modified FCM objective function, the new adaptive fuzzy clustering algorithm is capable of utilizing local contextual information in impose local spatial continuity, thus exploiting the high inter-pixel correlation inherent in most real-world images. The incorporation of local spatial continuity allows the suppression of noise and helps to resolve classification ambiguity. To account for smooth intensity variation within each homogenous region in an image, a multiplicative field is introduced to each of the fixed FCM cluster prototype. The muitiplicative field effectively makes the fixed cluster prototype adaptive to slow smooth within-cluster intensity variation, and allows homogenous regions with slow smooth intensity variation to be segmented as a whole. Experimental results with synthetic and real color images have shown the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]