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Publicações

2022

LNDb Dataset

Autores
Pedrosa, J; Aresta, G; Ferreira, CA; Rodrigues, M; Leitão, P; Carvalho, AS; Rebelo, J; Negrão, E; Ramos, I; Cunha, A; Campilho, A;

Publicação

Abstract

2022

University Entrepreneurship: The Process of Knowledge-based Value Creation

Autores
Sara Lúcia Correia Neves;

Publicação

Abstract

2022

Helping early obstructive sleep apnea diagnosis with machine learning: A systematic review (Preprint)

Autores
Ferreira-Santos, D; Amorim, P; Silva Martins, T; Monteiro-Soares, M; Pereira Rodrigues, P;

Publicação

Abstract
BACKGROUND

American Academy of Sleep Medicine guidelines suggests that clinical prediction algorithms can be used to screen obstructive sleep apnea (OSA) patients without replacing polysomnography (PSG) – the gold standard.

OBJECTIVE

We aimed to identify, gather, and analyze existing machine learning approaches that are being used for disease screening in adult patients suspected of OSA.

METHODS

We searched MEDLINE, Scopus and ISI Web of Knowledge databases for evaluating the validity of different machine learning techniques, with PSG as the gold standard outcome measures. This systematic review was registered in PROSPERO under reference CRD42021221339.

RESULTS

Our search retrieved 5479 articles, of which 63 articles were included. We found 23 studies performing diagnostic models’ development alone, 26 with added internal validation, and 14 applying the clinical prediction algorithm to an independent sample (although not all reporting the most common discrimination metrics - sensitivity and/or specificity). Logistic regression was applied in 35 studies, linear regression in 16, support vector machine in 9, neural networks in 8, decision trees in 6, and Bayesian networks in 4. Random forest, discriminant analysis, classification and regression tree, and nomogram were each performed in 2 studies, while Pearson correlation, adaptative neuro-fuzzy inference system, artificial immune recognition system, genetic algorithm, supersparse linear integer models, and k-nearest neighbors’ algorithm each in 1 study. The best AUC was .98 [.96-.99] for age, waist circumference, Epworth somnolence, and oxygen saturation as predictors in a logistic regression.

CONCLUSIONS

Although high values were obtained, they still lack external validation results in large cohorts and a standard OSA criteria definition.

2022

Understanding Overlap in Automatic Root Cause Analysis in Manufacturing Using Causal Inference

Autores
Oliveira, EE; Migueis, VL; Borges, JL;

Publicação
IEEE ACCESS

Abstract
Overlap has been identified in previous works as a significant obstacle to automated diagnosis using data mining algorithms, since it makes it impossible to discern how each machine influences product quality. Several solutions that handle overlap have been proposed, but the final result is a list of potential overlapped root causes. The goal of this paper is to develop a solution resilient to overlap that can determine the true root cause from a list of possible root causes, when possible, and determine the conditions in which it is possible to identify the root causes. This allows for a better understanding of overlap, and enables the development of a fully automatic root cause analysis for manufacturing. To do so, we propose an automatic root cause analysis approach that uses causal inference and do calculus to determine the true root cause. The proposed approach was validated on simulated and real case-study data, and allowed for an estimation of the effect of a product passing through a certain machine while disregarding the effect of overlap, in certain conditions. The results were on par with the state-of-the-art solutions capable of handling overlap. The contributions of this paper are a graphical definition of overlap, the identification of the conditions in which is possible to overcome the effect of overlap, and a solution that can present a single true root cause when such conditions are met.

2022

Spiking Neural Networks: A Survey

Autores
Nunes, JD; Carvalho, M; Carneiro, D; Cardoso, JS;

Publicação
IEEE ACCESS

Abstract
The field of Deep Learning (DL) has seen a remarkable series of developments with increasingly accurate and robust algorithms. However, the increase in performance has been accompanied by an increase in the parameters, complexity, and training and inference time of the models, which means that we are rapidly reaching a point where DL may no longer be feasible. On the other hand, some specific applications need to be carefully considered when developing DL models due to hardware limitations or power requirements. In this context, there is a growing interest in efficient DL algorithms, with Spiking Neural Networks (SNNs) being one of the most promising paradigms. Due to the inherent asynchrony and sparseness of spike trains, these types of networks have the potential to reduce power consumption while maintaining relatively good performance. This is attractive for efficient DL and, if successful, could replace traditional Artificial Neural Networks (ANNs) in many applications. However, despite significant progress, the performance of SNNs on benchmark datasets is often lower than that of traditional ANNs. Moreover, due to the non-differentiable nature of their activation functions, it is difficult to train SNNs with direct backpropagation, so appropriate training strategies must be found. Nevertheless, significant efforts have been made to develop competitive models. This survey covers the main ideas behind SNNs and reviews recent trends in learning rules and network architectures, with a particular focus on biologically inspired strategies. It also provides some practical considerations of state-of-the-art SNNs and discusses relevant research opportunities.

2022

THE SOCIAL REPRESENTATION OF THE GOVERNANCE SYSTEM THROUGH KEY DESCRIPTORS: MUTE ZONE?

Autores
Marchisotti, G; Filho, J; Franca, S; Domingos, M; Junior, V; Toledo, R; Alves, C; Castro, H; Putnik, G;

Publicação
INTERNATIONAL JOURNAL FOR QUALITY RESEARCH

Abstract
This article seeks to describe the social representations of Brazilians about the term Governance System (GS). The data were collected through online questionnaires answered by 665 social actors from Brazil. The data analysis used the Social Representation Theory (SRT), operationalized by the techniques of free evocation of words and the Four Houses Framework of Verges, followed by lexical and content analysis. It was identified that in the center of the table there are words highly shared by the social actors about the Governance System: Accountability, Administration, Compliance, Control, Management, Organization, Planning, Processes, Transparency, and Ethics. It is concluded that Accountability is conceived as a structuring element for the effectiveness of the GS. The data suggest the existence of a mute zone in the social representation, since there was a scarcity of words that brought negative expressions about the GS and that deserve future investigations.

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