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Publicações

Publicações por CRACS

2010

An integrated system for submission, assessment, feedback and publication of online digital portfolios

Autores
Figueira, A; Felix, C; Ferreira, C;

Publicação
Proceedings of the 8th IASTED International Conference on Web-Based Education, WBE 2010

Abstract
Digital portfolios have recently assumed an increasing importance in e-learning. In this article we report an integrated system that can be used to publish online projects undertaken by students during their courses. The system was then integrated with the Moodle learning management system featuring the possibility to create, evaluate, publish and maintain digital portfolios assigned and corrected by the institution faculty. This integrated process ensures a high quality level of the projects registered. The system uses information imported from Moodle's database to fill in its own database for users, courses and propagates the existing session between the two systems. It also maintains the projects in specific development phases, thus, allowing asynchronous editing, assessing or commenting on projects by different students or teachers. The creation of a new project is boosted by the use of a set of pre-defined templates which in turn give a standard layout and design quality to the final view of the project.

2010

Web-Based Intelligent Tutoring Systems Using the SCORM 2004 Specification - A Conceptual Framework for Implementing SCORM Compliant Intelligent Web-Based Learning Environments

Autores
Santos, G; Figueira, A;

Publicação
ICALT 2010, 10th IEEE International Conference on Advanced Learning Technologies, Sousse, Tunesia, 5-7 July 2010

Abstract
This paper describes a conceptual framework for implementing Intelligent Tutoring Systems using SCORM 2004. The main objective is to discuss how the SCORM 2004 sequencing and navigation specification can allow the development of Intelligent Web-Based Learning Environments using the sequencing and navigation tracking data, and rule set. Our main argument is that SCORM 2004 sequencing and navigation specification can be used to implement the two main functionalities of an ITS, (1) the inner loop and (2) the outer loop. © 2010 IEEE.

2010

Reusable and Inter-Operable Web-Based Intelligent Tutoring Systems Using SCORM 2004

Autores
Santos, G; Figueira, A;

Publicação
PROCEEDINGS OF THE 9TH EUROPEAN CONFERENCE ON E-LEARNING, VOL 1

Abstract
For several years Intelligent Tutoring Systems (ITSs) have been developed and shown to lead to impressive improvement in student learning in a range of domains. Some of the most important limitations of ITSs are that their development is very time consuming, and they cannot be reused or imported to different platforms. The main benefits of the Sharable Content Object Reference Model (SCORM) are interoperability and reusability. Based on the SCORM Sequencing and Navigation (SN) specification we have developed an approach for implementing Web-Based SCORM compliant ITSs that are therefore reusable and interoperable. The main objective of this paper is to describe our approach and explain how to implement SCORM compliant ITSs using as an example, a prototype that we built.

2010

PARALLEL CALCULATION OF SUBGRAPH CENSUS IN BIOLOGICAL NETWORKS

Autores
Ribeiro, P; Silva, F; Lopes, L;

Publicação
BIONFORMATICS 2010: PROCEEDINGS OF THE FIRST INTERNATIONAL CONFERENCE ON BIOINFORMATICS

Abstract
Mining meaningful data from complex biological networks is a critical task in many areas of research. One important example is calculating the frequency of all subgraphs of a certain size, also known as the sub graph census problem. This can provide a very comprehensive structural characterization of a network and is also used as an intermediate step in the computation of network motifs, an important basic building block of networks, that try to bridge the gap between structure and function. The subgraph census problem is com-putationally hard and here we present several parallel strategies to solve this problem. Our initial strategies were refined towards achieving an efficient and scalable adaptive parallel algorithm. This algorithm achieves almost linear speedups up to 128 cores when applied to a representative set of biological networks from different domains and makes the calculation of census for larger subgraph sizes feasible.

2010

g-tries: an efficient data structure for discovering network motifs

Autores
Pinto Ribeiro, PM; Silva, FMA;

Publicação
Proceedings of the 2010 ACM Symposium on Applied Computing (SAC), Sierre, Switzerland, March 22-26, 2010

Abstract
In this paper we propose a novel specialized data structure that we call g-trie, designed to deal with collections of subgraphs. The main conceptual idea is akin to a prefix tree in the sense that we take advantage of common topology by constructing a multiway tree where the descendants of a node share a common substructure. We give algorithms to construct a g-trie, to list all stored subgraphs, and to find occurrences on another graph of the subgraphs stored in the g-trie. We evaluate the implementation of this structure and its associated algorithms on a set of representative benchmark biological networks in order to find network motifs. To assess the efficiency of our algorithms we compare their performance with other known network motif algorithms also implemented in the same common platform. Our results show that indeed, g-tries are a feasible, adequate and very efficient data structure for network motifs discovery, clearly outperforming previous algorithms and data structures. © 2010 ACM.

2010

Efficient Parallel Subgraph Counting Using G-Tries

Autores
Pinto Ribeiro, PM; Silva, FMA; Lopes, LMB;

Publicação
Proceedings of the 2010 IEEE International Conference on Cluster Computing, Heraklion, Crete, Greece, 20-24 September, 2010

Abstract
Finding and counting the occurrences of a collection of subgraphs within another larger network is a computationally hard problem, closely related to graph isomorphism. The subgraph count is by itself a very powerful characterization of a network and it is crucial for other important network measurements. G-tries are a specialized data-structure designed to store and search for subgraphs. By taking advantage of subgraph common substructure, g-tries can provide considerable speedups over previously used methods. In this paper we present a parallel algorithm based precisely on gtries that is able to efficiently find and count subgraphs. The algorithm relies on randomized receiver-initiated dynamic load balancing and is able to stop its computation at any given time, efficiently store its search position, divide what is left to compute in two halfs, and resume from where it left. We apply our algorithm to several representative real complex networks from various domains and examine its scalability. We obtain an almost linear speedup up to 128 processors, thus allowing us to reach previously unfeasible limits. We showcase the multidisciplinary potential of the algorithm by also applying it to network motif discovery. © 2010 IEEE.

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