The cathedral and the bazaar of e-repository development: encouraging community engagement with moving pictures and sound

This paper offers an insight into the development, use and governance of e‐repositories for learning and teaching, illustrated by Eric Raymond's bazaar and cathedral analogies and by a comparison of collection strategies that focus on content coverage or on the needs of users. It addresses in particular the processes that encourage and achieve community engagement. This insight is illustrated by one particular e‐repository, the Education Media On‐Line (EMOL) service. This paper draws analogies between the bazaar approach for open source software development and its possibilities for developing e‐repositories for learning and teaching. It suggests in particular that the development, use and evaluation of online moving pictures and sound objects for learning and teaching can benefit greatly from the community engagement lessons provided by the development, use and evaluation of open source software. Such lessons can be underpinned by experience in the area of learning resource collections, where repositories have been classified as ‘collections‐based’ or ‘user‐based’. Lessons from the open source movement may inform the development of e‐repositories such as EMOL in the future

Final report, independent Study during Fall 2009 "Improving Collaborative Filtering in Social Tagging Systems for the Recommendation of Scientific Articles"

This report describes our study of different ways to improve existing collaborative filtering techniques in order to recommend scientific articles. Using data crawled from CiteUlike, a collaborative tagging service for academic purposes, we compared the classical user-based collaborative filtering algorithm as described by Schafer et al. [2], with two enhanced variations: 1) using a tag-based similarity calculation, to avoid depending on ratings to find the neighborhood of a user, and 2) incorporate the amount of raters in the final recommendation ranking to decrease the noise of items that have been rated by too few users. We provide a discussion of our results, describing the dataset and highlighting our findings about applying collaborative filtering on folksonomies instead of the classic bipartite user-item network, and providing guidelines of our future research

High-fidelity entanglement purification using chains of atoms and optical cavities

In our previous paper [Phys. Rev. A 84, 042303 (2011)], we proposed an efficient scheme to purify dynamically a bipartite entangled state using short chains of atoms coupled to high-finesse optical cavities. In contrast to conventional entanglement purification protocols, we avoid controlled-NOT gates and thus reduce complicated pulse sequences and superfluous qubit operations. In this paper, we significantly improve the output fidelity of remotely entangled atoms by introducing one additional entanglement protocol in each of the repeater nodes and by optimizing the laser beams required to control the entire scheme. Our improved distillation scheme yields an almost unit output fidelity that, together with the entanglement distribution and swapping, opens an attractive route towards an efficient and experimentally feasible quantum repeater for long-distance quantum communication.Comment: 13 pages, 4 figures, revised version accepted in PRA. arXiv admin note: text overlap with arXiv:1106.353