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Publications

2020

Network Analysis for Fraud Detection in Portuguese Public Procurement

Authors
Carneiro, D; Veloso, P; Ventura, A; Palumbo, G; Costa, J;

Publication
Intelligent Data Engineering and Automated Learning - IDEAL 2020 - 21st International Conference, Guimaraes, Portugal, November 4-6, 2020, Proceedings, Part II

Abstract
As technology evolves, frauds, in all their different forms, become increasingly more complex, as mega-processes such as Luanda Leaks or Panama Papers have recently shown. Fraud detection mechanisms must thus also resort to recent technological developments to ensure that even new forms of complex fraud are detected in time. In this paper we present a system to facilitate fraud detection in Public Procurement in Portugal. It relies on three main components. Data on public procurement and involved entities is acquired from public sources and integrated into a graph-oriented database. A rules-engine enriches these data with information additional information, using legal rules or custom rules defined by the users. Finally, a graph-oriented User Interface is used to support decision-making, allowing users to quickly and efficiently explore and filter information, in a natural and geo-referenced way. The main goal of this system is to increase transparency by facilitating access to relevant information, and in this way contribute to the fairness of the whole public procurement procedure. © 2020, Springer Nature Switzerland AG.

2020

Gaussian Mixture Model Based Probabilistic Modeling of Images for Medical Image Segmentation

Authors
Riaz, F; Rehman, S; Ajmal, M; Hafiz, R; Hassan, A; Aljohani, NR; Nawaz, R; Young, R; Coimbra, M;

Publication
IEEE ACCESS

Abstract
In this paper, we propose a novel image segmentation algorithm that is based on the probability distributions of the object and background. It uses the variational level sets formulation with a novel region based term in addition to the edge-based term giving a complementary functional, that can potentially result in a robust segmentation of the images. The main theme of the method is that in most of the medical imaging scenarios, the objects are characterized by some typical characteristics such a color, texture, etc. Consequently, an image can be modeled as a Gaussian mixture of distributions corresponding to the object and background. During the procedure of curve evolution, a novel term is incorporated in the segmentation framework which is based on the maximization of the distance between the GMM corresponding to the object and background. The maximization of this distance using differential calculus potentially leads to the desired segmentation results. The proposed method has been used for segmenting images from three distinct imaging modalities i.e. magnetic resonance imaging (MRI), dermoscopy and chromoendoscopy. Experiments show the effectiveness of the proposed method giving better qualitative and quantitative results when compared with the current state-of-the-art.

2020

Inscription of surface waveguides in glass by femtosecond laser writing for enhanced evanescent wave overlap

Authors
Amorim, VA; Maia, JM; Viveiros, D; Marques, PVS;

Publication
JOURNAL OF OPTICS

Abstract
Near-surface optical waveguides were fabricated in alkaline earth boro-aluminosilicate glass (Eagle2000), by femtosecond laser direct writing, using two distinct approaches. First, the capability of directly inscribing optical waveguides close to the surface was tested, and then, compared to the adoption of post writing wet etching to bring to the surface waveguides inscribed at greater depths. Laser ablation was found to limit the minimum surface to core center distance to 6.5 mu m in the first method, with anisotropic wet etching limiting the latter to 3 mu m without any surface deformation; smaller separations can be achieved at the cost of the planar surface topography. Furthermore, the waveguide's cross-section was seen to vary for laser inscription nearing the surface, observations that were also corroborated by its distinct guiding characteristics when compared to the adoption of post writing wet etching. The spectral analysis (in the 500-1700 nm range) also evidenced an increase in insertion loss for longer wavelengths and smaller surface to core center separations, caused, most likely, by coupling loss due to the interaction between the propagating mode and the surface. Different lengths of waveguide exposed to the surface were also tested, revealing that scattering loss due to surface roughness is not an issue at the centimeter scale.

2020

Can NAO Robot Influence the Eye Gaze and Joint Attention of Mentally Impaired Young Adults?

Authors
Freire, A; Valente, A; Filipe, V;

Publication
DSAI

Abstract
In the last decades due to technological advances, Robotics has change its paradigm, as well as, its course of development. Therefore, a new generation of robots has emerged, the Socially Assistive Robotics. These robots aim to improve the assistance to human users through social rather than physical interaction. Consequently, many are the developments made through the use of social robots in mental healthcare scenarios, regarding the elderly population and children or young adults with mental disorders, in order to either prevent cognitive decline, improve psycho-social outcomes or the patient capabilities and lifetime. However, few breakthroughs have been made in the mental disorders field that differ from studies with people with Autism Spectrum Disorders or that are conducted with adults. This study aims to demonstrate that humanoid NAO can improve attention in adults with mental disorders during certain task and kept through several sessions over time.

2020

A measure of the size of the magnetospheric accretion region in TW Hydrae

Authors
Lopez, RG; Natta, A; Garatti, ACO; Ray, TP; Fedriani, R; Koutoulaki, M; Klarmann, L; Perraut, K; Sanchez Bermudez, J; Benisty, M; Dougados, C; Labadie, L; Brandner, W; Garcia, PJV; Henning, T; Caselli, P; Duvert, G; de Zeeuw, T; Grellmann, R; Abuter, R; Amorim, A; Baub?ck, M; Berger, JP; Bonnet, H; Buron, A; Cl?net, Y; du Foresto, VC; de Wit, W; Eckart, A; Eisenhauer, F; Filho, M; Gao, F; Dabo, CEG; Gendron, E; Genzel, R; Gillessen, S; Habibi, M; Haubois, X; Haussmann, F; Hippler, S; Hubert, Z; Horrobin, M; Rosales, AJ; Jocou, L; Kervella, P; Kolb, J; Lacour, S; Le Bouquin, JB; L?na, P; Ott, T; Paumard, T; Perrin, G; Pfuhl, O; Ramirez, A; Rau, C; Rousset, G; Scheithauer, S; Shangguan, J; Stadler, J; Straub, O; Straubmeier, C; Sturm, E; van Dishoeck, E; Vincent, F; von Fellenberg, S; Widmann, F; Wieprecht, E; Wiest, M; Wiezorrek, E; Woillez, J; Yazici, S; Zins, G;

Publication
NATURE

Abstract
Stars form by accreting material from their surrounding disks. There is a consensus that matter flowing through the disk is channelled onto the stellar surface by the stellar magnetic field. This is thought to be strong enough to truncate the disk close to the corotation radius, at which the disk rotates at the same rate as the star. Spectro-interferometric studies in young stellar objects show that hydrogen emission (a well known tracer of accretion activity) mostly comes from a region a few milliarcseconds across, usually located within the dust sublimation radius(1-3). The origin of the hydrogen emission could be the stellar magnetosphere, a rotating wind or a disk. In the case of intermediate-mass Herbig AeBe stars, the fact that Brackett gamma (Br gamma) emission is spatially resolved rules out the possibility that most of the emission comes from the magnetosphere(4-6)because the weak magnetic fields (some tenths of a gauss) detected in these sources(7,8)result in very compact magnetospheres. In the case of T Tauri sources, their larger magnetospheres should make them easier to resolve. The small angular size of the magnetosphere (a few tenths of a milliarcsecond), however, along with the presence of winds(9,10)make the interpretation of the observations challenging. Here we report optical long-baseline interferometric observations that spatially resolve the inner disk of the T Tauri star TW Hydrae. We find that the near-infrared hydrogen emission comes from a region approximately 3.5 stellar radii across. This region is within the continuum dusty disk emitting region (7 stellar radii across) and also within the corotation radius, which is twice as big. This indicates that the hydrogen emission originates in the accretion columns (funnel flows of matter accreting onto the star), as expected in magnetospheric accretion models, rather than in a wind emitted at much larger distance (more than one astronomical unit). The size of the inner disk of the T Tauri star TW Hydrae is determined using optical long-baseline interferometric observations, indicating that hydrogen emission comes from a region approximately 3.5 stellar radii across.

2020

Game Elements, Motivation and Programming Learning: A Case Study

Authors
Carneiro, D; Silva, RJR;

Publication
First International Computer Programming Education Conference, ICPEC 2020, June 25-26, 2020, ESMAD, Vila do Conde, Portugal (Virtual Conference).

Abstract
The learning of programming is traditionally challenging for students. However, this is also one of the most fundamental skills for any computer scientist, and is becoming an important skill in other areas of knowledge. In this paper we analyze the use of game-elements in a challenging long-term programming task, with students of the 3rd year of a Informatics Engineering degree. We conducted a quantitative study using the AMS scale to assess students' motivation. Results show that with the use of game-elements, students are both intrinsically and extrinsically motivated, and that they consider learning/working fun, which contributes positively to their academic performance. 2012 ACM Subject Classification Human-centered computing!Collaborative and social computing theory, concepts and paradigms.

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