Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

2014

Connectivity patterns of pallidal DBS electrodes in focal dystonia: A diffusion tensor tractography study

Authors
Rozanski, VE; Vollmar, C; Cunha, JP; Neves Tafula, SMN; Ahmadi, SA; Patzig, M; Mehrkens, JH; Boetzel, K;

Publication
NEUROIMAGE

Abstract
Deep brain stimulation (DBS) of the internal pallidal segment (GPi: globus pallidus internus) is gold standard treatment for medically intractable dystonia, but detailed knowledge of mechanisms of action is still not available. There is evidence that stimulation of ventral and dorsal GPi produces opposite motor effects. The aim of this study was to analyse connectivity profiles of ventral and dorsal GPi. Probabilistic tractography was initiated from DBS electrode contacts in 8 patients with focal dystonia and connectivity patterns compared. We found a considerable difference in anterior-posterior distribution of fibres along the mesial cortical sensorimotor areas between the ventral and dorsal GPi connectivity. This finding of distinct GPi connectivity profiles further confirms the clinical evidence that the ventral and dorsal GPi belong to different functional and anatomic motor subsystems. Their involvement could play an important role in promoting clinical DBS effects in dystonia.

2014

Merging Decision Trees: A Case Study in Predicting Student Performance

Authors
Strecht, P; Mendes Moreira, J; Soares, C;

Publication
ADVANCED DATA MINING AND APPLICATIONS, ADMA 2014

Abstract
Predicting the failure of students in university courses can provide useful information for course and programme managers as well as to explain the drop out phenomenon. While it is important to have models at course level, their number makes it hard to extract knowledge that can be useful at the university level. Therefore, to support decision making at this level, it is important to generalize the knowledge contained in those models. We propose an approach to group and merge interpretable models in order to replace them with more general ones without compromising the quality of predictive performance. We evaluate our approach using data from the U. Porto. The results obtained are promising, although they suggest alternative approaches to the problem.

2014

Collaborative Framework for Dynamic Scheduling Supporting in Networked Manufacturing Environments

Authors
Varela, MLR; Santos, ASe; Madureira, AM; Putnik, GD; Cruz Cunha, MM;

Publication
Int. J. Web Portals

Abstract
Scheduling continues to play an important role in manufacturing systems. It enables the production of suitable scheduling plans, considering shared resources between several different products, through several manufacturing environments including networked ones. High levels of uncertainty characterize networked manufacturing environments. Processes have specific and complex requirements and management requisites, along with diversified objectives, which are dynamic and often conflicting. Dynamic adaptation and a real-time response for manufacturing scheduling is still possible and is critical in this new manufacturing environments, which have a flexible nature, where disturbances on working conditions occur on a continuous and even unexpected basis. Therefore, scheduling systems should have the ability of automatically and intelligently maintain a real-time adaptation and optimization of orders production, to effectively and efficiently adapt these manufacturing environments to the inherent dynamic of markets. In this paper a collaborative framework for supporting dynamic scheduling in networked manufacturing environments is proposed, based on a hyper-organization model and on hyper-heuristics, in order to obtain feasible and robust scheduling plans.

2014

Local municipalities' involvement in promoting the internationalisation of SMEs

Authors
Teixeira, AC; Barros, MJ;

Publication
Local Economy

Abstract
Despite extensive research on decentralisation, the role of local governments in promoting the internationalisation of firms has been rather neglected in the literature. Based on a sample of 144 Portuguese municipalities, and resorting to logistic econometric estimations, we found that: (1) the majority of municipalities have been involved in activities to promote economic development and the internationalisation of firms; (2) municipalities are essentially involved in the branding of regions (image building) or in organising fairs and trade missions and (3) municipalities more active in promoting the internationalisation of small and medium-sized enterprises (SMEs) tend to be more peripheral, with a relatively high area and population density, higher purchasing power, higher proportion of population with secondary schooling, lower density entrepreneurial context but with higher amounts of exports. Although there is still a long way to go for a more profound and comprehensive decentralisation at this level in Portugal, given the knowledge municipalities possess about the firms that are located in their vicinity, we contend that it would be desirable that more decentralised efforts be put towards the implementation of information, and education/training-related programmes aiming at promoting SMEs internationalisation. © The Author(s) 2014.

2014

Feature-based supervised lung nodule segmentation

Authors
Campos, DM; Simoes, A; Ramos, I; Campilho, A;

Publication
IFMBE Proceedings

Abstract
Lung nodule segmentation allows for automatic measurement of the nodule's size or volume which is of utmost importance in lung cancer diagnosis. It is a challenging task since there are many different types of nodules (solid or non-solid, solitary or multiple, etc). A supervised lung nodule segmentation method uses a shape-based, contrast-based and intensity-based feature set to produce three preliminary segmentations and an artificial neural network to obtain a more accurate segmentation. This method was applied to 20 computer tomography studies, all containing nodules. The data has 10 images of solid nodules and 10 images of ground glass opacity nodules, all with ground-truth. The segmentation uses a region growing approach and the volumetric shape index is used for nodule detection and providing a seed point. In the first and second segmentation the probability of each neighbor belonging to the nodule is estimated using the volumetric shape index and the convergence index filter, respectively. The third segmentation is obtained using a feature set region regression method where for each neighbor the probability of belonging to the nodule or not is obtained using k nearest neighbor regression. Then, using a leave-one out method, an artificial neural network uses the three preliminary segmentations as input and is trained to obtain a more accurate segmentation. Results obtained a 12% relative volume error, 88% and 93% Jaccard and Dice coefficient respectively. © 2014, Springer International Publishing Switzerland.

2014

Rekindles or one-o quality in forest fire fighting: validating the pressure on firefighters and implications for forest fire management in Portugal

Authors
Pacheco, AP; Claro, J; Oliveira, T;

Publication
Advances in forest fire research

Abstract

  • 2974
  • 4541