On the Feasibility of Real-Time HRV Estimation Using Overly Noisy PPG Signals

Funding Information: This work was funded by the Fundação para a Ciência e Tecnologia (FCT, Portugal) and NMT, S.A in the scope of the PhD grant PD/BDE/150312/2019 and by FCT within the scope of the CTS Research Unit—Center of Technology and Systems—UNINOVA, under the project UIDB/00066/2020 (FCT). Publisher Copyright: © 2022 by the authors.Heart Rate Variability (HRV) is a biomarker that can be obtained non-invasively from the electrocardiogram (ECG) or the photoplethysmogram (PPG) fiducial points. However, the accuracy of HRV can be compromised by the presence of artifacts. In the herein presented work, a Simulink® model with a deep learning component was studied for overly noisy PPG signals. A subset with these noisy signals was selected for this study, with the purpose of testing a real-time machine learning based HRV estimation system in substandard artifact-ridden signals. Home-based and wearable HRV systems are prone to dealing with higher contaminated signals, given the less controlled environment where the acquisitions take place, namely daily activity movements. This was the motivation behind this work. The results for overly noisy signals show that the real-time PPG-based HRV estimation system produced RMSE and Pearson correlation coefficient mean and standard deviation of 0.178 ± 0.138 s and 0.401 ± 0.255, respectively. This RMSE value is roughly one order of magnitude above the closest comparative results for which the real-time system was also used.publishersversionpublishe

The application of deep learning algorithms for PPG signal processing and classification

Funding Information: This research was funded by the Funda??o para a Ci?ncia e Tecnologia (FCT, Lisbon, Portugal) and NMT, S.A in the scope of the PhD grant PD/BDE/150312/2019 and by FCT within the scope of the CTS Research Unit?Center of Technology and Systems?UNINOVA, under the project UIDB/00066/2020 (FCT). Funding Information: Funding: This research was funded by the Fundação para a Ciência e Tecnologia (FCT, Lisbon, Portugal) and NMT, S.A in the scope of the PhD grant PD/BDE/150312/2019 and by FCT within the scope of the CTS Research Unit—Center of Technology and Systems—UNINOVA, under the project UIDB/00066/2020 (FCT). Publisher Copyright: © 2021 by the authorsLicensee MDPI, Basel, Switzerland.Photoplethysmography (PPG) is widely used in wearable devices due to its conveniency and cost-effective nature. From this signal, several biomarkers can be collected, such as heart and respiration rate. For the usual acquisition scenarios, PPG is an artefact-ridden signal, which mandates the need for the designated classification algorithms to be able to reduce the noise component effect on the classification. Within the selected classification algorithm, the hyperparameters’ adjustment is of utmost importance. This study aimed to develop a deep learning model for robust PPG wave detection, which includes finding each beat’s temporal limits, from which the peak can be determined. A study database consisting of 1100 records was created from experimental PPG measurements performed in 47 participants. Different deep learning models were implemented to classify the PPG: Long Short-Term Memory (LSTM), Bidirectional LSTM, and Convolutional Neural Network (CNN). The Bidirectional LSTM and the CNN-LSTM were investigated, using the PPG Synchrosqueezed Fourier Transform (SSFT) as the models’ input. Accuracy, precision, recall, and F1-score were evaluated for all models. The CNN-LSTM algorithm, with an SSFT input, was the best performing model with accuracy, precision, and recall of 0.894, 0.923, and 0.914, respectively. This model has shown to be competent in PPG detection and delineation tasks, under noise-corrupted signals, which justifies the use of this innovative approach.publishersversionpublishe

Peak Detection and HRV Feature Evaluation on ECG and PPG Signals

Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Heart Rate Variability (HRV) evaluates the autonomic nervous system regulation and can be used as a monitoring tool in conditions such as cardiovascular diseases, neuropathies and sleep staging. It can be extracted from the electrocardiogram (ECG) and the photoplethysmogram (PPG) signals. Typically, the HRV is obtained from the ECG processing. Being the PPG sensor widely used in clinical setups for physiological parameters monitoring such as blood oxygenation and ventilatory rate, the question arises regarding the PPG adequacy for HRV extraction. There is not a consensus regarding the PPG being able to replace the ECG in the HRV estimation. This work aims to be a contribution to this research area by comparing the HRV estimation obtained from simultaneously acquired ECG and PPG signals from forty subjects. A peak detection method is herein introduced based on the Hilbert transform: Hilbert Double Envelope Method (HDEM). Two other peak detector methods were also evaluated: Pan-Tompkins and Wavelet-based. HRV parameters for time, frequency and the non-linear domain were calculated for each algorithm and the Pearson correlation, T-test and RMSE were evaluated. The HDEM algorithm showed the best overall results with a sensitivity of 99.07% and 99.45% for the ECG and the PPG signals, respectively. For this algorithm, a high correlation and no significant differences were found between HRV features and the gold standard, for the ECG and PPG signals. The results show that the PPG is a suitable alternative to the ECG for HRV feature extraction.publishersversionpublishe

Predictors of photic phenomena with a trifocal IOL

© 2021 Espaillat et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution - Non Commercial (unported, v3.0) License.Aim: To assess predictive factors associated with glares and halos in patients undergoing cataract surgery with PanOptix trifocal IOL implantation. Methods: Single-center retrospective study. One hundred and forty eyes from 70 patients with cataract were bilaterally implanted with a trifocal PanOptix aspherical diffractive lens between 2017 and 2019 and followed-up for six months. All patients were evaluated for refraction, corneal topography, and aberrometry pre- and post-operatively. Patients were assessed at 1 day, 6 days, 1 and 6 months after surgery. One and six months post-operatively patients were asked to complete a satisfaction questionnaire that included photic phenomena assessment. Main outcome measures were photic phenomena at 1 and 6 months of follow-up. Predictors of photic phenomena at 1 and 6 months were also analyzed. Results: A higher corneal coma was associated with more mild halos at 6 months with no association regarding other degrees of severity. The lower the age the higher the glare or halos, the higher the lens thickness and the lower the anterior chamber depth or chord μ the less halos at 1 month. A significant proportion of patients had more none/mild compared to moderate/severe glare and halos both at 1 and 6 months post-operatively. Baseline BCVA was the only predictor of halos at 1 month and glare and halos at 6 months post-surgery. Conclusion: On multivariate regression analyses, the only predictor of photic phenomena was baseline visual acuity, suggesting that patients that have a better visual acuity before surgery are more demanding regarding visual outcomes after surgery.info:eu-repo/semantics/publishedVersio

Effect of insecticides growth regulators on eggs, larvae and adults of Grapholita molesta (BUSCK) (LEP.: Tortricidae)

O trabalho teve como objetivo avaliar o efeito de inseticidas reguladores de crescimento de insetos (RCI) sobre ovos, lagartas e adultos de G. molesta, em laboratório. Os inseticidas avaliados foram lufenurom e novalurom (4,0g de i.a. 100L-1) metoxifenozida e tebufenozida (9,6g de i.a. 100L-1) e uma testemunha (água destilada). Em aplicação antes da oviposição, somente o metoxifenozida causou mortalidade significativa de ovos (26,3%), quando comparado à testemunha. A aplicação dos inseticidas sobre ovos com diferentes idades (24; 48 e 72 horas) apresentou variações na mortalidade da espécie em função do inseticida e tempo de desenvolvimento embrionário. Somente metoxifenozida e novalurom reduziram a viabilidade de lagartas que eclodiram dos ovos tratados, com um máximo de 35,9 e 39,5% de viabilidade larval quando aplicados em ovos de 48-72 horas, respectivamente. O tratamento dos frutos de maçã com inseticidas causou mortalidade significativa das lagartas, contudo não foram observadas diferenças entre os inseticidas, tanto para lagartas pequenas (eficiência média de 47,2%), quanto para lagartas de 3º-4º instar (média de 45,3%). Lufenurom reduziu sua eficácia com o aumento do tamanho da lagarta. A ingestão de lufenurom, metoxifenozida, novalurom, tebufenozida e por adultos de G. molesta reduziu a fecundidade e a fertilidade, porém a longevidade dos adultos somente foi afetada negativamente pela ingestão de metoxifenozida e tebufenozida.The objective of this study were to evaluate the effect of insecticides insect growth regulators (IGR's) on eggs, larvae and adults of G. molesta, in the laboratory. The evaluated insecticides were Lufenuron and Novaluron (4.0g of a.i. 100L-1), Methoxyfenozide and Tebufenozide (9.6g of a.i. 100L-1) and control (distilled water). In application before oviposition, only Methoxyfenozide caused significant mortality of eggs (26.3%) compared to control. The application of insecticides on eggs of different ages (24, 48 and 72 hours) showed variations in mortality of the species regarding the insecticide and time of embryonic development. Only Methoxyfenozide and Novaluron reduced the viability of larvae that emerged from treated eggs, with a maximum of 35.9% and 39.5 of larval viability when applied on eggs of 48-72 hours, respectively. The treatment of apple fruit with insecticides caused significant mortality of larvae, but no differences were observed among insecticides, both for small larvae (average efficiency of 47.2%) and for 3-4rd instar larvae (averaging 45.3%). Lufenuron reduced its efficacy on 3-4rd instar larvae. The ingestion of Lufenuron, Methoxyfenozide, Novaluron and Tebufenozide by adults of G. molesta reduced fecundity and fertility, however the adult longevity was only negatively affected by the ingestion of Methoxyfenozide and Tebufenozide.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Comparative performance of lab tests and blood testing device to monitor glucose, total cholesterol and triacylglycerol in type 2 diabetic patients

Comparou-se a performance de avaliação da glicemia através de dosagens laboratoriais (DL) ou dispositivo para teste de sangue capilar (DTSC) vs. hemoglobina glicada A1c (A1c). Comparou-se ainda a performance de avaliação da glicemia, colesterol total (CT) e triacilglicerol (DL vs. DTSC). Avaliou-se estes parametros a partir das mesmas amostras de sangue coletadas em pacientes diabéticos tipo 2 (PDT2) em jejum noturno, sendo as comparações realizadas através de análise de regressão linear. A A1c correlacionou-se melhor com a glicemia-DL (r = 0,58) em relação a glicemia-DTSC (r = 0,42). Comparou-se DL vs. DTSC obtendo se r = 0,90, 0,82 e 0,92 para glicemia, CT e triacilglicerol, respectivamente. Concluiu-se que houve melhor performance da glicose-DL em relação a glicose-DTSC. Além disso, considerando que o triacilglicerol e TC avaliado através de DTSC correlaciona-se melhor com DL em comparação a DTSC-glicose vs. DL-glicose, a inclusão de DTSC-TC e DTSC-triacilglicerol visando detectar e monitorar hyperlipidemia in PDT2 deve ser considerada.The performance of lab tests (LT) and blood testing devices (BTD) to monitor glycemia vs. glycated hemoglobin A1c (A1c) were compared. In addition, the performance of blood glucose, total cholesterol (TC) and triacylglycerol measured by LT and BDT were compared. All parameters were measured based on the same blood samples from overnight fasted type 2 diabetic patients (T2DP). Linear regression analysis was used for all comparisons. The results showed that A1c correlated better with LT-glucose (r = 0.58) than BTD-glucose (r = 0.42). Moreover, LT vs. BTD showed r values of 0.90, 0.82 and 0.92 for glucose, TC and triacylglycerol, respectively. It was concluded that the performance of LT-glucose was better than BDT-glucose. Moreover, since triacylycerol and TC measured by BTD correlated better with LT compared to BDT-glucose vs. LT-glucose, the inclusion of BTD-TC and BTD-triacylglycerol for detecting and monitoring hyperlipidemia in T2DP should be considered

A contribution for the automatic sleep classification based on the Itakura-Saito spectral distance

Sleep staging is a crucial step before the scoring the sleep apnoea, in subjects that are tested for this condition. These patients undergo a whole night polysomnography recording that includes EEG, EOG, ECG, EMG and respiratory signals. Sleep staging refers to the quantification of its depth. Despite the commercial sleep software being able to stage the sleep, there is a general lack of confidence amongst health practitioners of these machine results. Generally the sleep scoring is done over the visual inspection of the overnight patient EEG recording, which takes the attention of an expert medical practitioner over a couple of hours. This contributes to a waiting list of two years for patients of the Portuguese Health Service. In this work we have used a spectral comparison method called Itakura distance to be able to make a distinction between sleepy and awake epochs in a night EEG recording, therefore automatically doing the staging. We have used the data from 20 patients of Hospital Pulido Valente, which had been previously visually expert scored. Our technique results were promising, in a way that Itakura distance can, by itself, distinguish with a good degree of certainty the N2, N3 and awake states. Pre-processing stages for artefact reduction and baseline removal using Wavelets were applied.publishersversionpublishe

PROPUESTA PARA EL PROCESO DE FORMACIÓN DEL PENSAMIENTO MATEMÁTICO LATERAL EN LA EDUCACIÓN SUPERIOR ANGOLANA

El presente artículo tiene como objetivo explicar las insuficiencias epistemológicas que se revelan en los Institutos Superiores de Ciencias de la Educación en la República de Angola. Entre dichas insuficiencias se destacan: las irregularidades en el proceso de comunicación oral en relación con la orientación contextualizada de los egresados, lo que limita  el perfeccionamiento del  proceso formativo debido a la multitud de símbolos matemáticos que se aprenden en la enseñanza media con respecto a la enseñanza superior; la incoherencia entre las explicaciones verbales, la acción práctica y su formulación en el plano metodológico, restringe el potencial reflexivo, lo que conduce a formar futuros profesionales con deficiencias que inciden en el conocimiento de naturaleza compleja, por consiguiente, se manifiesta la necesidad de establecer la mediación sistemática  entre el lenguaje y el pensamiento matemático lateral complejo. Para su elaboración se utilizaron el método histórico-lógico, el análisis documental, la comparación por partes y la técnica de muestreo aleatorio estratificado

Formación matemática sistematizada a partir del enfoque ciencia, tecnología y sociedad, en el perfil ingenieril

La actual investigación se desarrolló como parte de una formación doctoral y su ejecución en el desempeño pedagógico desde 2013 hasta 2018, la cual se socializa a través de un artículo científico, a partir del proceso de formación matemática. Se posibilita metodológicamente el perfeccionamiento del proceso formativo, a fin de elevar los niveles de sistematización cognitiva, sustentado en una relación establecida entre la abstracción matemática científica y la generalización matemática investigativa; como posición epistemológica para solución de problemas profesionales, enfocados en la Ciencia, Tecnología y Sociedad (CTS). Su implementación parcial se realizó en los estudiantes del tercer y cuarto año académico, en las carreras de Ingeniería Civil, Informática, Electrónica, Telecomunicación e Información en las Instituciones de la Enseñanza Superior (IES) angoleñas. Además, los resultados alcanzados en la pesquisa con la utilización del método histórico-lógico, el análisis documental y la técnica de muestreo aleatorio estatificado son valorados por algunos profesores, quienes tuvieron relación directa con la formación matemática, quienes posibilitaron el procesamiento de la información, a través del empleó del software IBM SPSS Statistics 20; logrando una transformación cuali-cuantitativa en el proceso de enseñanza-aprendizaje de la Matemática, mediante proyecciones investigativas de mayor pertinencia, teniendo en cuenta las demandas sociales y la adecuada implementación de los aportes científicos reconocidos por la Comunidad Científica. Así se facilitó la inserción en el contexto, en función de resolver las diversas problemáticas de la profesión y del territorio donde se reside, provocando cambios en el rol estudiantil, la economía, y en la prestación de los servicios

ÉTICA, MÉTODO E EXPERIMENTAÇÃO ANIMAL: a questão do especismo nas ciências experimentais

Análise das questões éticas suscitadas a partir do uso dos animais para fins científicos na atualidade. A experimentação animal é decorrente da valoração instrumental que os animais humanos atribuem aos demais animais, algo que tem suas raízes associadas à História e às tradições. Apresentamse as formas de compreensão idealizadas pelos humanos sobre os animais, a partir do discurso filosófico, teológico e científico, de onde emerge a necessidade de se discutirem essas questões a partir de critérios éticos/bioéticos. Investigam-se os argumentos favoráveis e contrários ao uso dos animais pela ciência, com base na possibilidade de formulação de um status moral para os animais, atualmente reconhecidos como seres dotados de sensibilidade e direitos. A importância deste estudo está em promover o debate filosófico sobre a apropriação dos animais por humanos, identificando nos discursos especistas (aqueles que defendem o avanço da ciência) e antiespecistas (aqueles que lutam pela proteção dos animais) mecanismos de poder e controle de determinados grupos sociais em detrimentos de outros. Palavras-chave: Filosofia. Ciência. Experimentação animal. Ética.ETHICS, METHOD AND ANIMAL EXPERIMENTATION: the question of the specism in the experimental sciencesAbstract: Analysis of ethical issues arising from the use of animals for scientific purposes nowadays. Animal experimentation is a result of instrumental valuation that human animals attribute to other animals, something that has its roots associated with the history and traditions. The idealized forms of understanding by humans about animals, from the philosophical, theological and scientific discourses, from which emerges  the need to discuss those issues from ethical/bioethical viewpoints are investigated. The arguments for and against the use of animals by science, based on the possibility of formulating a moral status to animals, currently recognized as beings endowed of sensibility and rights. The importance of this study is to promote the philosophical debate about human use of animals, identifying in speeches speciesists (those who advocate the advancement of science) and anti-speciesists (those who fight for animal protection) mechanisms of power and control of certain social groups at the expenses of other.Keywords: Philosophy. Science. Animal experimentation. Ethics.ÉTICA, MÉTODO Y EXPERIMENTACIÓN ANIMAL: el problema del especismo en las ciencias experimentalesResumen: Un análisis de los problemas éticos derivados de la utilización de animales para fines científicos en la actualidad. La experimentación con animales es el resultado de la valoración fundamental que los seres humanos atribuyen a los demás animales, algo que tiene sus raíces asociadas con la historia y las tradiciones. Muestranse las formas idealizadas de comprensión por parte de los humanos sobre los animales, desde el discurso filosófico, teológico y científico, de donde surge la necesidad de discutir estas cuestiones a partir de criterios éticos/bioéticos. Investigación de los argumentos a favor y en contra de la utilización de animales en la ciencia, basada em la posibilidad de establecer un estatuto moral de los animales, actualmente reconocido como seres sensibles y de derechos. La importância de este estudio es promover el debate filosófico acerca de la utilización que los humanos tienen sobre los demás animales, identificandose em los discursos especistas (los que abogan por el avance de la ciencia) y antiespecistas (aquellos que luchan por la protección de los animales) los mecanismos de poder y control de determinados grupos sociales a expensas de los demás.Palabras clave: Filosofía. Ciencia. Experimentación con animales. Ética