Insect herbivores can shift the composition of a plant community, but the mechanism underlying such shifts remains largely unexplored. A possibility is that insects alter the competitive symmetry between plant species. The effect of herbivory on competition likely depends on whether the plants are subjected to aboveground or belowground herbivory or both, and also depends on soil nitrogen level...

This paper describes a study of a simple open learner model that can be optionally released to peers in named or anonymous form, to facilitate collaborative and competitive learning in a situation where the learner model contents contributed to students' assessment. Results suggest that, under the right conditions, students may start working sooner; discussion amongst students can be increased;...

Most developed countries exhibit high rates of R&D performed in industry, but the situation is considerable different in medium income countries such as Portugal. Despite the lower levels of R&D, Portuguese firms have increased their competitiveness, and the country has been able to show remarkable levels of economic performance. This paper provides a framework to analyze the way in which R&D i...

Mining local structure is important in data analysis. Gaussian mixture is able to describe local structure through the covariance matrices, but when used on highdimensional data, fitly specifying such a large number of d(d + 1)=2 free elements in each covariance matrix is difficult. In this paper, by constraining the covariance matrix in decomposed orthonormal form, we propose a Local PCA algor...

Article history: Received 5 April 2015 Received in revised form 30 May 2015 Accepted 2 June 2015 Available online 9 June 2015 Communicated by D.-Z. Du