2024
Authors
Leite, S; Mota, B; Silva, AR; Commons, ML; Miller, PM; Rodrigues, PP;
Publication
PLOS ONE
Abstract
Several studies demonstrate that the structure of the brain increases in hierarchical complexity throughout development. We tested if the structure of artificial neural networks also increases in hierarchical complexity while learning a developing task, called the balance beam problem. Previous simulations of this developmental task do not reflect a necessary premise underlying development: a more complex structure can be built out of less complex ones, while ensuring that the more complex structure does not replace the less complex one. In order to address this necessity, we segregated the input set by subsets of increasing Orders of Hierarchical Complexity. This is a complexity measure that has been extensively shown to underlie the complexity behavior and hypothesized to underlie the complexity of the neural structure of the brain. After segregating the input set, minimal neural network models were trained separately for each input subset, and adjacent complexity models were analyzed sequentially to observe whether there was a structural progression. Results show that three different network structural progressions were found, performing with similar accuracy, pointing towards self-organization. Also, more complex structures could be built out of less complex ones without substituting them, successfully addressing catastrophic forgetting and leveraging performance of previous models in the literature. Furthermore, the model structures trained on the two highest complexity subsets performed better than simulations of the balance beam present in the literature. As a major contribution, this work was successful in addressing hierarchical complexity structural growth in neural networks, and is the first that segregates inputs by Order of Hierarchical Complexity. Since this measure can be applied to all domains of data, the present method can be applied to future simulations, systematizing the simulation of developmental and evolutionary structural growth in neural networks.
2023
Authors
Pereira, RC; Rodrigues, PP; Figueiredo, MAT; Abreu, PH;
Publication
ICCS (1)
Abstract
Missing data can be described by the absence of values in a dataset, which can be a critical issue in domains such as healthcare. A common solution for this problem is imputation, where the missing values are replaced by estimations. Most imputation methods are suitable for the Missing Completely At Random (MCAR) and Missing At Random (MAR) mechanisms but produce biased results for Missing Not At Random (MNAR) values. An effective approach to mitigate this bias effect is to use the delta-adjustment method. This method assumes the imputation is performed for the MAR mechanism and adjusts the imputed values to become valid under MNAR assumptions by applying a correction factor. Such adjustment is usually defined manually by a domain expert, which often makes this method unfeasible. In this work, we propose an automatic procedure to find an approximate delta adjustment value for every feature of the dataset, which we call Automatic Delta-Adjustment Method. The proposed procedure is validated in an experimental setup comprising 10 datasets of the healthcare domain injected with MNAR values. The results from seven state-of-the-art imputation methods are compared with and without the adjustment, and applying the correction provides a significantly lower imputation error for all methods.
2023
Authors
Pereira, RC; Abreu, PH; Rodrigues, PP;
Publication
ICCS (1)
Abstract
Missing data is an issue that can negatively impact any task performed with the available data and it is often found in real-world domains such as healthcare. One of the most common strategies to address this issue is to perform imputation, where the missing values are replaced by estimates. Several approaches based on statistics and machine learning techniques have been proposed for this purpose, including deep learning architectures such as generative adversarial networks and autoencoders. In this work, we propose a novel siamese neural network suitable for missing data imputation, which we call Siamese Autoencoder-based Approach for Imputation (SAEI). Besides having a deep autoencoder architecture, SAEI also has a custom loss function and triplet mining strategy that are tailored for the missing data issue. The proposed SAEI approach is compared to seven state-of-the-art imputation methods in an experimental setup that comprises 14 heterogeneous datasets of the healthcare domain injected with Missing Not At Random values at a rate between 10% and 60%. The results show that SAEI significantly outperforms all the remaining imputation methods for all experimented settings, achieving an average improvement of 35%.
2023
Authors
Rodrigues, MG; Rodrigues, JD; Soares, MM; Azevedo, LF; Rodrigues, PP; Areias, JC; Areias, ME;
Publication
QUALITY OF LIFE RESEARCH
Abstract
PurposeTo identify psychoeducational interventions that target parents of children with congenital abnormalities (CA) and evaluate their impact on quality of life (QoL).MethodsThe search was conducted in six electronic databases, complemented by references of the studies found, studies of evidence synthesis, a manual search of relevant scientific meetings' abstracts and contact with experts. We included primary studies on parents of children with CA that studied psychoeducational interventions versus standard care. We assessed the risk of bias using Cochrane Collaboration's tool.ResultsWe included six studies focusing on congenital heart defects (CHD). They described four different psychoeducational strategies. In four studies, statistically significant differences were found. For clinical practice, we considered three interventions as more feasible: the Educational program for mothers, with a group format of four sessions weekly; CHIP-Family intervention, which includes a parental group workshop followed by an individual follow-up booster session; and WeChat educational health program with an online format.ConclusionsThis review is the first that assesses the impact of psychoeducational interventions targeted at parents of children with CA on their QoL. The best approach to intervention is multiple group sessions. Two essential strategies were to give support material, enabling parents to review, and the possibility of an online program application, increasing accessibility. However, because all included studies focus on CHD, generalizations should be made carefully. These findings are crucial to guide future research to promote and improve comprehensive and structured support for families and integrate them into daily practice.
2023
Authors
Duarte, M; Pereira Rodrigues, P; Ferreira Santos, D;
Publication
JOURNAL OF MEDICAL INTERNET RESEARCH
Abstract
Background: Digital clinical tools are a new technology that can be used in the screening or diagnosis of obstructive sleep apnea (OSA), notwithstanding the crucial role of polysomnography, the gold standard.Objective: This study aimed to identify, gather, and analyze the most accurate digital tools and smartphone-based health platforms used for OSA screening or diagnosis in the adult population. Methods: We performed a comprehensive literature search of PubMed, Scopus, and Web of Science databases for studies evaluating the validity of digital tools in OSA screening or diagnosis until November 2022. The risk of bias was assessed using the Joanna Briggs Institute critical appraisal tool for diagnostic test accuracy studies. The sensitivity, specificity, and area under the curve (AUC) were used as discrimination measures.Results: We retrieved 1714 articles, 41 (2.39%) of which were included in the study. From these 41 articles, we found 7 (17%) smartphone-based tools, 10 (24%) wearables, 11 (27%) bed or mattress sensors, 5 (12%) nasal airflow devices, and 8 (20%) other sensors that did not fit the previous categories. Only 8 (20%) of the 41 studies performed external validation of the developed tool. Of these, the highest reported values for AUC, sensitivity, and specificity were 0.99, 96%, and 92%, respectively, for a clinical cutoff of apnea-hypopnea index (AHI)& GE;30. These values correspond to a noncontact audio recorder that records sleep sounds, which are then analyzed by a deep learning technique that automatically detects sleep apnea events, calculates the AHI, and identifies OSA. Looking at the studies that only internally validated their models, the work that reported the highest accuracy measures showed AUC, sensitivity, and specificity values of 1.00, 100%, and 96%, respectively, for a clinical cutoff AHI & GE;30. It uses the Sonomat-a foam mattress that, aside from recording breath sounds, has pressure sensors that generate voltage when deformed, thus detecting respiratory movements, and uses it to classify OSA events.Conclusions: These clinical tools presented promising results with high discrimination measures (best results reached AUC>0.99). However, there is still a need for quality studies comparing the developed tools with the gold standard and validating them in external populations and other environments before they can be used in clinical settings.
2023
Authors
Duarte, M; Pereira-Rodrigues, P; Ferreira-Santos, D;
Publication
Abstract Clinical digital tools are an up-and-coming new technology that can be used in the screening or diagnosis of obstructive sleep apnea (OSA) patients, notwithstanding the crucial role of polysomnography (PSG) – the gold standard. The aim of our study was to identify, gather, and analyze existing digital tools and smartphone-based health platforms that are being used for this disease’s screening or diagnosis in the adult population. We performed a comprehensive literature search in MEDLINE, Scopus, and Web of Science databases for studies evaluating the validity of digital tools in OSA screening or diagnosis until November 2022. The risk of bias was assessed using JBI Critical Appraisal Tool for Diagnostic Test Accuracy Studies. Sensitivity, specificity, and area under the receiver-operating curve (AUC) were used as discrimination measures. We retrieved 1714 articles, 41 of which were included. We found 7 smartphone-based tools, 10 wearables, 11 bed/mattress sensors, 5 nasal airflow devices, and 8 other sensors that did not fit the previous categories. Only 8 (20%) studies performed external validation of their developed tool. Of those, the highest reported values for AUC, sensitivity, and specificity were 0.99, 96%, and 92%, respectively, for a clinical cutoff of apnea-hypopnea index (AHI) = 30 and correspond to a non-contact audio recorder that records sleep sounds, which are then analyzed by a deep learning technique that automatically detects sleep apnea events, calculates the AHI, and identifies OSA. Looking at the studies that only internally validated their models, the work that reported the highest accuracy measures showed AUC, sensitivity, and specificity values of 1.00, 100%, and 96%, respectively, for a clinical cutoff AHI = 30. It uses the Sonomat – a foam mattress that, aside from recording breath sounds, has pressure sensors that generate voltage when deformed, thus detecting respiratory movements, and using it to classify OSA events. These clinical tools presented promising results, showing high discrimination measures (best results reaching AUC > 0.99). However, there is still a need for quality studies, comparing the developed tools with the gold standard and validating them in external populations and other environments before they can be used in a clinical setting. This systematic review was registered in PROSPERO under reference CRD42023387748.
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