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Publicações

Publicações por LIAAD

2015

An agent-based electronic market simulator enhanced with ontology matching services and emergent social networks

Autores
Nascimento, V; Viamonte, MJ; Canito, A; Silva, N;

Publicação
International Journal of Simulation and Process Modelling

Abstract
AEMOS is a simulator which aims to support the development of agent-based electronic markets capable of dealing with the natural semantic heterogeneity existent in this kind of environment. AEMOS simulates a marketplace which provides ontology matching services, enhanced with the exploitation of emergent social networks, enabling an efficient and transparent communication between agents, even when they use different ontologies. The system recommends possible alignments between the agents' ontologies, and lets them negotiate and decide which alignment should be used to translate the exchanged messages. In this paper we propose a new ontology alignment negotiation process, which promotes the reutilisation and combination of already existing alignments, as well as the involvement of business agents in the alignment composition process. With this new model, we aim to achieve a higher adequacy of the used alignments, as well as a more accurate and trustful evaluation of the alignments. Copyright © 2015 Inderscience Enterprises Ltd.

2015

A survey of task-oriented crowdsourcing

Autores
Luz, N; Silva, N; Novais, P;

Publicação
ARTIFICIAL INTELLIGENCE REVIEW

Abstract
Since the advent of artificial intelligence, researchers have been trying to create machines that emulate human behaviour. Back in the 1960s however, Licklider (IRE Trans Hum Factors Electron 4-11, 1960) believed that machines and computers were just part of a scale in which computers were on one side and humans on the other (human computation). After almost a decade of active research into human computation and crowdsourcing, this paper presents a survey of crowdsourcing human computation systems, with the focus being on solving micro-tasks and complex tasks. An analysis of the current state of the art is performed from a technical standpoint, which includes a systematized description of the terminologies used by crowdsourcing platforms and the relationships between each term. Furthermore, the similarities between task-oriented crowdsourcing platforms are described and presented in a process diagram according to a proposed classification. Using this analysis as a stepping stone, this paper concludes with a discussion of challenges and possible future research directions.

2015

Missing data imputation on the 5-year survival prediction of breast cancer patients with unknown discrete values

Autores
Garcia Laencina, PJ; Abreu, PH; Abreu, MH; Afonoso, N;

Publicação
COMPUTERS IN BIOLOGY AND MEDICINE

Abstract
Breast cancer is the most frequently diagnosed cancer in women. Using historical patient information stored in clinical datasets, data mining and machine learning approaches can be applied to predict the survival of breast cancer patients. A common drawback is the absence of information, i.e., missing data, in certain clinical trials. However, most standard prediction methods are not able to handle incomplete samples and, then, missing data imputation is a widely applied approach for solving this inconvenience. Therefore, and taking into account the characteristics of each breast cancer dataset, it is required to perform a detailed analysis to determine the most appropriate imputation and prediction methods in each clinical environment This research work analyzes a real breast cancer dataset from Institute Portuguese of Oncology of Porto with a high percentage of unknown categorical information (most clinical data of the patients are incomplete), which is a challenge in terms of complexity. Four scenarios are evaluated: (I) 5-year survival prediction without imputation and 5-year survival prediction from cleaned dataset with (II) Mode imputation, (Ill) Expectation-Maximization imputation and (IV) K-Nearest Neighbors imputation. Prediction models for breast cancer survivability are constructed using four different methods: K-Nearest Neighbors, Classification Trees, Logistic Regression and Support Vector Machines. Experiments are performed in a nested ten-fold cross-validation procedure and, according to the obtained results, the best results are provided by the K-Nearest Neighbors algorithm: more than 81% of accuracy and more than 0.78 of area under the Receiver Operator Characteristic curve, which constitutes very good results in this complex scenario.

2015

Male breast cancer: Looking for prognostic subgroups.

Autores
Abreu, MH; Afonso, N; Abreu, PH; Menezes, F; Lopes, P; Henrique, R; Pereira, D; Lopes, C;

Publicação
JOURNAL OF CLINICAL ONCOLOGY

Abstract
Purpose: Male Breast Cancer (MBC) remains a poor understood disease. Prognostic factors are not well established and specific prognostic subgroups are warranted. Patients/methods: Retrospectively revision of 111 cases treated in the same Cancer Center. Blinded-central pathological revision with immunohistochemical (IHQ) analysis for estrogen (ER), progesterone (PR) and androgen (AR) receptors, HER2, ki67 and p53 was done. Cox regression model was used for uni/multivariate survival analysis. Two classifications of Female Breast Cancer (FBC) subgroups (based in ER, PR, HER2, 2000 classification, and in ER, PR, HER2, ki67, 2013 classification) were used to achieve their prognostic value in MBC patients. Hierarchical clustering was performed to define subgroups based on the six-IHQ panel. Results: According to FBC classifications, the majority of tumors were luminal: A (89.2%; 60.0%) and B (7.2%; 35.8%). Triple negative phenotype was infrequent (2.7%; 3.2%) and HER2 enriched, non-luminal, was rare (=1% in both). In multivariate analysis the poor prognostic factors were: size >2 cm (HR:1.8; 95%CI:1.0-3.4years, p = 0.049), absence of ER (HR:4.9; 95%CI:1.7-14.3years, p = 0.004) and presence of distant metastasis (HR:5.3; 95%CI:2.2-3.1years, p < 0.001). FBC subtypes were independent prognostic factors (p = 0.009, p = 0.046), but when analyzed only luminal groups, prognosis did not differ regardless the classification used (p > 0.20). Clustering defined different subgroups, that have prognostic value in multivariate analysis (p = 0.005), with better survival in ER/PR+, AR-, HER2-and ki67/p53 low group (median: 11.5 years; 95%CI: 6.2-16.8 years) and worst in PR-group (median:4.5 years; 95%CI: 1.6-7.8 years). Conclusion: FBC subtypes do not give the same prognostic information in MBC even in luminal groups. Two subgroups with distinct prognosis were identified in a common six-IHQ panel. Future studies must achieve their real prognostic value in these patients. © 2015 Elsevier Ltd.

2015

CYP2D6*4 polymorphism: A new marker of response to hormonotherapy in male breast cancer?

Autores
Abreu, MH; Gomes, M; Menezes, F; Afonso, N; Abreu, PH; Medeiros, R; Pereira, D; Lopes, C;

Publicação
BREAST

Abstract
Background: Tamoxifen remains the standard hormonotherapy for Male breast cancer patients (MBC). Previous studies, in women, tried to evaluate the impact of CYP2D6 polymorphisms in tamoxifen efficacy with conflicting results. Herein we analyze the relation between CYP2D6*4 polymorphism and survival in MBC patients. Patients and methods: Fifty-three patients, proposed to tamoxifen in adjuvant setting, were enrolled. Clinical information was collected from records and histological revision with additional immunochemistry analysis was done to better characterize the tumors. Comprehensive CYP2D6*4 genotyping from blood or tumor tissue was performed and translated into two predicted metabolic activity groups. Results: Patients included in the two CYP2D6*4 groups did not differ concerning to age, histological characteristics, and primary treatments performed. Median age at diagnosis was 63 years-old and patients were submitted at least to mastectomy and adjuvant hormonotherapy. Recurrence was observed in 7 patients (13.2%) and 13 patients (25.5%) died with a 5-year disease-free survival of 86.2%. The poorer metabolizer group had a high risk for recurrence (p = 0.034) and this outcome effect remains in different subgroups: in tumors larger than 2 cm (p < 0.001), nodal status, N0 vs N+ (p = 0.04) and in advanced stage, stage III (p < 0.001). Poorer metabolizer patients had also a worse overall survival when tumors were larger than 2 cm (p = 0.03). Conclusions: In our series, there was an association between CYP2D6*4 polymorphism and a probability of recurrence, with a consistent effect in risk groups defined by classic prognostic factors. Multicentric studies with larger samples are needed to validate these results.

2015

MoCaS: Mobile Carpooling System

Autores
Ribeiro, A; Silva, DC; Abreu, PH;

Publicação
NEW CONTRIBUTIONS IN INFORMATION SYSTEMS AND TECHNOLOGIES, VOL 1, PT 1

Abstract
Carpooling is a car sharing practice first adopted in the United States of America during the fuel crisis in the 1970s. Since then, and after some ups and downs, this practice has been growing in recent years, being currently used throughout the world. With the evolution of mobile technologies, carpooling had the opportunity to expand, especially through mobile applications and web pages. With these technologies, it is possible for anyone in any part of the globe to search for others that wish to go to the same place and want to share their car. With this practice, people intend to save money, help preserve the environment, reduce congestions in cities, increase the number of places available to park and meet new people. This paper introduces MoCaS Mobile Carpooling System, a carpool service offered for registered users. In this system, each user can enter his travels and make appointments, assign ratings, register vehicles and add travel preferences. All this is possible via a web interface and also via a mobile application that together give greater support to those seeking such services. MoCaS distinguishes itself from other systems by offering innovative services, namely in the mobile component, that through location services allows for the booking of trips in real-time; in other words, not only trips that have not started, but trips that are already underway and that end up intersecting the user's position. Besides this novelty, this system provides a real-time map, where all trip stops are visible, as well as the location of carpoolers who are currently traveling. Both the web and the mobile applications were successfully developed, achieving good results in the performed tests, and are currently being prepared for deployment.

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