Spectral features related to the auditory perception of twang-like voices.

BACKGROUND: To the best of our knowledge, studies on the relationship between spectral energy distribution and the degree of perceived twang-like voices are still sparse. Through an auditory-perceptual test we aimed to explore the spectral features that may relate with the auditory-perception of twang-like voices. METHODS: Ten judges who were blind to the test's tasks and stimuli rated the amount of twang perceived on seventy-six audio samples. The stimuli consisted of twenty voices recorded from eight CCM singers who sustained the vowel [a:] in different pitches, with and without a twang-like voice. Also, forty filtered and sixteen synthesized-manipulated stimuli were included. RESULTS AND CONCLUSIONS: Based on the intra-rater reliability scores, four judges were identified as suitable to be included in the analyses. Results showed that the frequency of F1 and F2 correlated strongly with the auditory-perception of twang-like voices (0.90 and 0.74, respectively), whereas F3 showed a moderate negative correlation (-0.52). The frequency difference between F1 and F3 showed a strong negative correlation (-0.82). The mean energy between 1-2 kHz and 2-3 kHz correlated moderately (0.51 and 0.42, respectively). The frequency of F4 and F5, and the energy above 3 kHz showed weak correlations. Since the spectral changes under 2 kHz have been associated with the jaw, lips, and tongue adjustments (i.e. vowel articulation) and a higher vertical laryngeal position might affect the frequency of all formants (including F1 and F2), our results suggest that vowel articulation and the laryngeal height may be relevant when performing twang-like voices.

Análisis cepstral de la voz normal y patológica en español colombiano mediante el uso del programa PRAAT / Cepstral analysis of normal and pathological voice in Colombian Spanish using the PRAAT program

Introducción: las medidas auditivo-perceptuales subjetivas GRABS (Grade [grado de gravedad], Roughness [aspereza], Asthenia [astenia], Breathiness [soplosidad] y Strain [tensión] y CAPE-V (Consensus Auditory-Perceptual Evaluation of Voice) han sido el estándar de oro en evaluar la voz. La prominencia del pico cepstral suavizado (CPPS) se impone como la medida acústica objetiva más robusta para evaluar la gravedad de la disfonía. Se evaluó el análisis cepstral del programa PRAAT en pacientes con voz patológica y no patológica en hablantes de español colombiano y los valores estándar para el CPPS en lenguaje conectado (CPPSc), comparado con el análisis perceptual de la voz (GRBAS). Métodos: estudio observacional y analítico de prueba diagnóstica, de corte transversal y multicéntrico, con 120 individuos. Se grabó la voz y se analizó el CPPSc con el programa PRAAT. Se aplicó la valoración auditiva-perceptual por dos evaluadores expertos para la escala GRBAS. Resultados: el promedio de edad fue 43,3 años, 64,2 % mujeres. La media del CPPSc en el grupo disfónico fue de 6,40 dB y en el grupo de normofónicos fue 8,54 dB con p=0,000. Sensibilidad de 83,6% y especificidad de 96,2 % para la voz patológica en los pacientes con valores de CPPSc menores a 7,38 dB. Hubo alta correlación del valor de CPPSc con la gravedad de la disfonía. Conclusiones: el valor del CPPSc mediante el programa PRAAT es una medida eficiente por su alta validez, bajo costo y fácil aplicación para evaluar objetivamente la disfonía y su gravedad.

Introduction: Subjective auditory-perceptual measurements, GRABS (Grade, Roughness, Asthenia, Breathiness y Strain) and CAPE-V (Consensus Auditory Perceptual Evaluation of Voice) have been the gold standard in voice evaluation. Recently, the smoothed cepstral peak prominence (CPPS) has been imposed as the acoustic measurement, objective and more robust for dysphonia severity. Objectives: The cepstral analysis of the PRAAT program was evaluated in patients with a patho-logical and non-pathological voice in Colombian Spanish speakers and the standard values for the CPPS in connected language (CPPSc), compared with the perceptual analysis of the voice (GRBAS). Methods: An observational, analytical, cross-sec-tional, multicenter diagnostic test was performed with 120 individuals. The voice was recorded and the CPPSc was analyzed with the PRAAT program. The auditory-perceptual assessment was applied by two expert evaluators for the GRBAS scale. Results: The average age was 43.3 ± 18.1 years, 64.2% were women. The mean CPPSc in the dysphonic group was 6.40 dB, while in the group of normophonic indi-viduals it was 8.54 dB, with significant differences between both groups (p=0.000). Sensitivity of 83.6% and specificity of 96.2%; for pathological voice was established in patients with CPPSc values less than 7.38 dB. A high correlation was found in the CPPSc value with the severity of dysphonia. Conclusions: The value of CPPSc through the Praat program is an efficient measure, due to its high validity, low cost and easy application to objectively evaluate dysphonia and its severity.

Performance of self-etching adhesives on caries-affected primary dentin treated with glutaraldehyde or silver diamine fluoride.

OBJECTIVES: to evaluate the quality and stability of adhesive interfaces established by self-etching adhesives on caries-affected primary dentin (CAD) treated with glutaraldehyde (GA) or silver diamine fluoride (SDF). METHODS: 42 primary molars were exposed to a microbiological caries-inducing protocol and divided into 6 groups according to the adhesive system (Clearfil SE - CL or FL Bond II - FL) and pretreatment (water, GA or SDF) applied on CAD. One tooth from each group was analyzed for surface modification using infrared spectroscopy. Crowns were restored with resin composite (n = 36) and cut into beams and slices. The beams were subjected to microtensile testing, Raman spectroscopy and SEM after 24 h and 6 months of storage. The slices were analyzed using Micro-Raman spectroscopy to determine the diffusion zone thickness (DZ) in each period. Data were analyzed by ANOVA and Tukey or Kruskal-Wallis and Dunn tests (α = 0.05%). RESULTS: SDF reduced the immediate bond strength for both adhesives. The control groups showed a decrease in BS after 6 months in artificial saliva. GA increased immediate DZ for FL, while SDF had the opposite effect on CL. GA decreased the DZ for FL at 6 months. There was a predominance of adhesive failures with areas of cohesive dentin fractures within control groups. SIGNIFICANCE: Modifications caused by dentin surface treatments may directly affect the performance of adhesive systems and the quality and stability of adhesive restorations.

Quantitative EEG analysis in typical absence seizures: unveiling spectral dynamics and entropy patterns.

A typical absence seizure is a generalized epileptic event characterized by a sudden, brief alteration of consciousness that serves as a hallmark for various generalized epilepsy syndromes. Distinguishing between similar interictal and ictal electroencephalographic (EEG) epileptiform patterns poses a challenge. However, quantitative EEG, particularly spectral analysis focused on EEG rhythms, shows potential for differentiation. This study was designed to investigate discernible differences in EEG spectral dynamics and entropy patterns during the pre-ictal and post-ictal periods compared to the interictal state. We analyzed 20 EEG ictal patterns from 11 patients with confirmed typical absence seizures, and assessed recordings made during the pre-ictal, post-ictal, and interictal intervals. Power spectral density (PSD) was used for the quantitative analysis that focused on the delta, theta, alpha, and beta bands. In addition, we measured EEG signal regularity using approximate (ApEn) and multi-scale sample entropy (MSE). Findings demonstrate a significant increase in delta and theta power in the pre-ictal and post-ictal intervals compared to the interictal interval, especially in the posterior brain region. We also observed a notable decrease in entropy in the pre-ictal and post-ictal intervals, with a more pronounced effect in anterior brain regions. These results provide valuable information that can potentially aid in differentiating epileptiform patterns in typical absence seizures. The implications of our findings are promising for precision medicine approaches to epilepsy diagnoses and patient management. In conclusion, our quantitative analysis of EEG data suggests that PSD and entropy measures hold promise as potential biomarkers for distinguishing ictal from interictal epileptiform patterns in patients with confirmed or suspected typical absence seizures.

Combining spectral analysis and geochemical tracers to investigate surface water-groundwater interactions: A case study in an intensive agricultural setting (southern Guatemala).

An increase in the frequency of severe hydrological events has highlighted the importance of sustainable water management in intensive agricultural regions. In a warming climate, improved understanding and stewardship of water resources are needed to guarantee water supply, ensure food security, and build resilience against extreme events. In this study, we evaluate a framework that combines spectral analysis and geochemical tracers as a potential tool for (1) gaining valuable insights into surface water (SW)-groundwater (GW) interactions, and (2) providing guidance for improved water management in an intensive agricultural basin in southern Guatemala. The framework proves to be useful in revealing important water dynamics, exposing key feedback mechanisms for water availability and quality. With the use of power density functions and hydrochemistry (T, pH, EC, and major ions), two specific interaction regimes (influent and effluent) were identified and delimited for the main watercourse. These segments are estimated to interact at high rates with the shallow aquifer in the river channel proximities and would lose influence towards the basin flanks. Furthermore, the δ2H and δ18O values indicate that regional groundwater flow systems play an essential role in the basin groundwater recharge. Lastly, we established three influence zones that depict the spatial extent of the SW-GW interactions within the basin. With these zones, we provide recommendations that will allow for further investigation and application into better water management strategies regulating groundwater development and land use activities within the agricultural context of the area.

Espectroscopía visible y del infrarrojo cercano para el análisis de nutrientes en tejido vegetal de caña de azúcar para producción de panela

La espectroscopía de reflectancia en el infrarrojo cercano (NIRS) es una tecnología rápida, multiparamétrica, amigable con el ambiente, de bajo costo y gran exactitud, para el análisis de diversos componentes en alimentos, en suelo y en agricultura. El objetivo del presente estudio fue construir modelos de calibración NIRS, para la predicción de nutrientes en tejido vegetal de caña de azúcar, para producción de panela, cultivada en la región de la Hoya del río Suárez. Un total de 416 muestras de tejido fueron escaneadas en el segmento espectral Vis-NIR. El análisis quimiométrico, se realizó con el software WinISI V4.10, aplicando la regresión de mínimos cuadrados parciales modificados, junto a una validación cruzada. Se evaluaron cuatro modelos con diferentes tratamientos matemáticos y el rendimiento de las calibraciones, se hizo por medio de la validación externa, analizando las medidas de bondad de ajuste, como el coeficiente de determinación de la predicción, el error estándar de la predicción ajustado por el sesgo y la desviación predictiva residual. Los resultados muestran que el modelo de calibración para N presentó el mayor poder predictivo. Para macronutrientes, las calibraciones, con mayor poder predictivo, fueron P y K y para micronutrientes, el modelo para B, mientras que para Cu presentó el más bajo poder predictivo. Se encontraron modelos adecuados para la predicción de los contenidos de N, Ca y P; para los demás nutrientes, se recomienda ampliar el conjunto de calibración.

Near Infrared Reflectance Spectroscopy (NIRS) is a fast, multiparametric, environmentally friendly, low-cost, and highly accurate technology for the analysis of components in food, soil, and agriculture. The purpose of this study was to generate NIRS calibration models for the prediction of nutrients in plant tissue of sugarcane to panela production cultivated in the Hoya del Río Suárez region. A total of 416 tissue samples were scanned in Vis-NIR spectral segment. Chemometric analysis was performed with the WinISI V4.10 software applying modified partial least squares regression with cross-validation. Four models with different mathematical treatments were evaluated, and the performance of calibrations was made through external validation analyzing the goodness-of-fit measures as prediction determination coefficient, standard error of the bias-adjusted prediction, and residual predictive deviation. The results showed that the calibration model for N had the highest predictive power. For macronutrients, the calibrations with the best predictive power were for P and K, and micronutrients for B, while Cu presented the lowest predictive power. Adequate models were found for the prediction of N, Ca, and P. In the case of the other nutrients, it is recommended to expand the calibration set.

An Adaptive Mapping Method Using Spectral Envelope Approach for DNA Spectral Analysis.

The digital signal processing approaches were investigated as a preliminary indicator for discriminating between the protein coding and non-coding regions of DNA. This is because a three-base periodicity (TBP) has already been proven to exist in protein-coding regions arising from the length of codons (three nucleic acids). This demonstrates that there is a prominent peak in the energy spectrum of a DNA coding sequence at frequency 13 rad/sample. However, because DNA sequences are symbolic sequences, these should be mapped into one or more signals such that the hidden information is highlighted. We propose, therefore, two new algorithms for computing adaptive mappings and, by using them, finding periodicities. Both such algorithms are based on the spectral envelope approach. This adaptive approach is essentially important since a single mapping for any DNA sequence may ignore its intrinsic properties. Finally, the improved performance of the new methods is verified by using them with synthetic and real DNA sequences as compared to the classical methods, especially the minimum entropy mapping (MEM) spectrum, which is also an adaptive method. We demonstrated that our method is both more accurate and more responsive than all its counterparts. This is especially important in this application since it reduces the risks of a coding sequence being missed.

Automatic Classification of Subjects of the PSEN1-E280A Family at Risk of Developing Alzheimer's Disease Using Machine Learning and Resting State Electroencephalography.

BACKGROUND: The study of genetic variant carriers provides an opportunity to identify neurophysiological changes in preclinical stages. Electroencephalography (EEG) is a low-cost and minimally invasive technique which, together with machine learning, provide the possibility to construct systems that classify subjects that might develop Alzheimer's disease (AD). OBJECTIVE: The aim of this paper is to evaluate the capacity of the machine learning techniques to classify healthy Non-Carriers (NonCr) from Asymptomatic Carriers (ACr) of PSEN1-E280A variant for autosomal dominant Alzheimer's disease (ADAD), using spectral features from EEG channels and brain-related independent components (ICs) obtained using independent component analysis (ICA). METHODS: EEG was recorded in 27 ACr and 33 NonCr. Statistical significance analysis was applied to spectral information from channels and group ICA (gICA), standardized low-resolution tomography (sLORETA) analysis was applied over the IC as well. Strategies for feature selection and classification like Chi-square, mutual informationm and support vector machines (SVM) were evaluated over the dataset. RESULTS: A test accuracy up to 83% was obtained by implementing a SVM with spectral features derived from gICA. The main findings are related to theta and beta rhythms, generated in the parietal and occipital regions, like the precuneus and superior parietal lobule. CONCLUSION: Promising models for classification of preclinical AD due to PSEN-1-E280A variant can be trained using spectral features, and the importance of the beta band and precuneus region is highlighted in asymptomatic stages, opening up the possibility of its use as a screening methodology.

Heart rate variability in children: methodological issues and clinical applications. / Variabilidad del ritmo cardíaco en pediatría: aspectos metodológicos y aplicaciones clínicas.

Heart rate variability (HRV) corresponds to variations in heart rate or beat-beat time interval. This parameter reflects the status of the autonomic mechanisms of cardiovascular control, which may be influenced by changes characteristic of the life cycle of people, sedentary lifestyle, and various disease processes that directly or indirectly generate changes in the HRV and shift the autonomic balance, either towards greater sympathetic or parasympathetic influence on the heart. These antecedents support the use of HRV indices for the diagnosis and monitoring of various nosological entities in adults. However, there has been limited progress in the study of temporal variations in heart rhythm in the pediatric population. This article aims to describe the physiological and technical aspects of HRV in the pediatric population to provide a background that allows optimizing the application of these parameters in this age group.

La variabilidad del ritmo cardíaco (VRC) corresponde a las variaciones temporales de la frecuencia cardíaca o del intervalo latido-latido. Este parámetro refleja el estado de los mecanismos autonómicos de control cardiovascular. Los cambios propios del ciclo vital de las personas, el sedentarismo y diversos procesos de enfermedad han mostrado inducir cambios en la VRC y desplazar el balance autonómico hacia una mayor influencia simpática o parasimpática sobre el corazón. Estos antecedentes apoyan el uso de los índices de VRC para el diagnóstico y seguimiento de diversas entidades nosológicas en el adulto. Sin embargo, en la población pediátrica ha existido un limitado avance en el estudio de las variaciones temporales del ritmo cardíaco. Este artículo tiene por objetivo describir los aspectos fisiológicos y técnicos de la VRC en población pediátrica. El propósito es aportar antecedentes que permitan optimizar la aplicación de estos parámetros en este grupo etario.

Preservation of EEG spectral power features during simultaneous EEG-fMRI.

Introduction: Electroencephalographic (EEG) data quality is severely compromised when recorded inside the magnetic resonance (MR) environment. Here we characterized the impact of the ballistocardiographic (BCG) artifact on resting-state EEG spectral properties and compared the effectiveness of seven common BCG correction methods to preserve EEG spectral features. We also assessed if these methods retained posterior alpha power reactivity to an eyes closure-opening (EC-EO) task and compared the results from EEG-informed fMRI analysis using different BCG correction approaches. Method: Electroencephalographic data from 20 healthy young adults were recorded outside the MR environment and during simultaneous fMRI acquisition. The gradient artifact was effectively removed from EEG-fMRI acquisitions using Average Artifact Subtraction (AAS). The BCG artifact was corrected with seven methods: AAS, Optimal Basis Set (OBS), Independent Component Analysis (ICA), OBS followed by ICA, AAS followed by ICA, PROJIC-AAS and PROJIC-OBS. EEG signal preservation was assessed by comparing the spectral power of traditional frequency bands from the corrected rs-EEG-fMRI data with the data recorded outside the scanner. We then assessed the preservation of posterior alpha functional reactivity by computing the ratio between the EC and EO conditions during the EC-EO task. EEG-informed fMRI analysis of the EC-EO task was performed using alpha power-derived BOLD signal predictors obtained from the EEG signals corrected with different methods. Results: The BCG artifact caused significant distortions (increased absolute power, altered relative power) across all frequency bands. Artifact residuals/signal losses were present after applying all correction methods. The EEG reactivity to the EC-EO task was better preserved with ICA-based correction approaches, particularly when using ICA feature extraction to isolate alpha power fluctuations, which allowed to accurately predict hemodynamic signal fluctuations during the EEG-informed fMRI analysis. Discussion: Current software solutions for the BCG artifact problem offer limited efficiency to preserve the EEG spectral power properties using this particular EEG setup. The state-of-the-art approaches tested here can be further refined and should be combined with hardware implementations to better preserve EEG signal properties during simultaneous EEG-fMRI. Existing and novel BCG artifact correction methods should be validated by evaluating signal preservation of both ERPs and spontaneous EEG spectral power.

Efeito das irradiações ultravioleta (UV) e light emitting diode (LED) nas propriedades mecânicas dos alinhadores transparentes de poliuretano (PU) / Effect of ultraviolet (UV) and light emitting diode (LED) irradiations on the mechanical properties of transparent polyurethane (PU) aligners

O objetivo do presente estudo in vitro é investigar possíveis alterações nas propriedades mecânicas de alinhadores transparentes de poliuretano (PU). Em um estudo piloto, amostras de alinhadores foram submetidas à Espectroscopia Raman antes e depois de irradiações de UV e de LED, e os resultados demonstraram evidente alteração da estrutura molecular. Em virtude disso, foi levantada a hipótese de que as radiações também provoquem alterações nas propriedades mecânicas. Foram confeccionados trinta alinhadores, pela empresa Align Technology Inc. (Invisalign ®), distribuídos em três grupos de dez alinhadores cada. Um grupo controle não sofreu irradiação, e os outros dois grupos foram irradiados: um com radiação UV dentro de uma câmara construída para esse tipo de experimento e um terceiro grupo com radiação LED por fotopolimerizador específico. Os grupos foram definidos, as irradiações foram efetuadas sob sigilo por um operador e as identificações, armazenadas em envelopes lacrados, somente foram reveladas após a conclusão dos testes e tabulação dos dados obtidos. Para avaliação das propriedades mecânicas, neste caso resistência à deformação, utilizou-se uma máquina de ensaio universal para o teste de carga. Os alinhadores foram preenchidos com gesso, com um alívio que deixou livres as áreas a serem testadas. O teste de tensão mostrou que tendo como referência o grupo controle, os alinhadores submetidos à radiação UV tornaram-se menos rígidos e os submetidos à radiação LED tornaram-se mais rígidos. O teste de H de Kruskal-Wallis foi realizado e evidenciou não haver diferença estatisticamente significativa na carga aplicada nas amostras dos diferentes grupos. O mesmo teste foi utilizado para avaliar a diferença entre a deformação ocorrida e o módulo de elasticidade nos três grupos. A hipótese nula foi rejeitada em ambos os testes, considerando o nível de 5% de significância, o que assegura que há uma diferença significativa entre os três grupos quanto à irradiação de UV ou LED. Ainda assim, para uma avaliação mais minuciosa utilizou-se o teste de Mann-Whtiney comparando os grupos dois a dois. O resultado apontou que as irradiações aplicadas neste estudo são responsáveis pelas diferenças estatísticas apresentadas. (AU)

The aim of the present in vitro study is to investigate possible changes in the mechanical properties of transparent polyurethane (PU) aligners. In a pilot study, specimens of aligners were subjected to Raman Spectroscopy before and after UV and LED irradiation, and the results showed evident alteration of the molecular structure. Because of this, it was hypothesized that the radiations also cause changes in the mechanical properties. Thirty aligners were made by Align Technology Inc. (Invisalign®), distributed in three groups of ten aligners each. A control group was not irradiated, and the other two groups were irradiated: one with UV radiation inside a chamber built for this type of experiment, and the third group with LED radiation by a specific photopolymerizer. The groups were defined, the irradiations were done under confidentiality by an operator and the identifications, stored in sealed envelopes, were only revealed after the completion of the tests and tabulation of the data obtained. To evaluate the mechanical properties, in this case resistance to deformation, a universal testing machine was used for the load test. The aligners were filled with plaster, with a relief that left free the areas to be tested. The tension test showed that taking the control group as reference, the aligners submitted to UV radiation became less rigid and those submitted to LED radiation became more rigid. The Kruskal-Wallis H test was performed and showed that there was no statistically significant difference in the load applied to the samples of the different groups. The same test was used to evaluate the difference between the deformation occurred and the modulus of elasticity in the three groups. The null hypothesis was rejected in both tests, considering the 5% significance level, which ensures that there is a significant difference between the three groups regarding UV or LED irradiation. Even so, for a more detailed evaluation the Mann-Whtiney test was used, comparing the groups two by two. The result pointed out that the irradiations applied in this study are responsible for the statistical differences presented (AU)

Does high-definition transcranial direct current stimulation change brain electrical activity in professional female basketball players during free-throw shooting?

Differentiated brain activation in high-performance athletes supports neuronal mechanisms relevant to sports performance. Preparation for the motor action involves cortical and sub-cortical regions that can be non-invasively modulated by electrical current stimulation. This study aimed to investigate the effect of high-definition transcranial direct current stimulation (HD-tDCS) on electrical brain activity in professional female basketball players during free-throw shooting. Successful free-throw shooting (n = 2,361) from seven professional female basketball players was analyzed during two experimental conditions (HD-tDCS cathodic and sham) separated by 72 h. Three spectral bio-markers, Power Ratio Index (PRI), Delta Alpha Ratio (DAR), and Theta Beta Ratio (TBR) were measured (electroencephalography [EEG] Brain Products). Multi-channel HD-tDCS was applied for 20 min, considering current location and intensity for cathodic stimulation: FCC1h, AFF5h, AFF1h (-0.5 mA each), and FCC5h (ground). The within EEG analyses (pre and post HD-tDCS) of frontal channels (Fp1, Fp2, F3, F4, FC1, FC3) for 1 second epoch pre-shooting, showed increases in PRI (p < 0.001) and DAR (p < 0.001) for HD-tDCS cathodic condition, and in TBR for both conditions (cathodic, p = 0.01; sham, p = 0.002). Sub-group analysis divided the sample into less (n = 3; LSG) and more (n = 4; MSG) stable free-throw-shooting performers and revealed that increases in pre to post HD-tDCS in PRI only occurred for the LSG. These results suggest that the effect of HD-tDCS may induce changes in slow frontal frequency brain activities and that this alteration seems to be greater for players demonstrating a less stable free-throw shooting performance.

Quantifying muscle alterations in a Parkinson's disease animal model using electromyographic biomarkers.

Parkinson's disease (PD) is a neurodegenerative disease currently diagnosed based on characteristic motor dysfunctions. The most common Parkinson's disease animal model induces massive nigrostriatal degeneration by intracerebral infusion of 6-hydroxydopamine (6-OHDA). Motor deficits in rat models of Parkinson's disease were previously addressed in other works. However, an accurate quantification of muscle function in freely moving PD-lesioned rats over time has not been described until now. In this work, we address the muscular activity characterization of a 6-OHDA-lesion model of PD along 6 weeks post-lesion based on spectral and morphological analysis of the signals. Using chronic implanted EMG electrodes in a hindlimb muscle of freely moving rats, we have evaluated the effect of the PD neurotoxic model in the muscular activity during locomotion. EMG signals obtained from animals with different time post-injury were analyzed. Power spectral densities were characterized by the mean and median frequency, and the EMG burst stationarity was previously verified for all animals. Our results show that as the time post-lesion increases both frequency parameters decrease. Probability distribution function analysis was also performed. The results suggest that contractile dynamics of the biceps femoris muscle change with time post-lesion. We have also demonstrated here the usefulness of frequency parameters as biomarkers for monitoring the muscular function changes that could be used for early detection of motor dysfunction.

Natural Frequencies Identification by FEM Applied to a 2-DOF Planar Robot and Its Validation Using MUSIC Algorithm.

In this paper, the natural frequencies (NFs) identification by finite element method (FEM) is applied to a two degrees-of-freedom (2-DOF) planar robot, and its validation through a novel experimental methodology, the Multiple Signal Classification (MUSIC) algorithm, is presented. The experimental platforms are two different 2-DOF planar robots with different materials for the links and different types of actuators. The FEM is carried out using ANSYS™ software for the experiments, with vibration signal analysis by MUSIC algorithm. The advantages of the MUSIC algorithm against the commonly used fast Fourier transform (FFT) method are also presented for a synthetic signal contaminated by three different noise levels. The analytical and experimental results show that the proposed methodology identifies the NFs of a high-resolution robot even when they are very closed and when the signal is embedded in high-level noise. Furthermore, the results show that the proposed methodology can obtain a high-frequency resolution with a short sample data set. Identifying the NFs of robots is useful for avoiding such frequencies in the path planning and in the selection of controller gains that establish the bandwidth.

A low-cost IoT multi-spectral acquisition device.

Color and lighting quality assessment allow users to reliably examine the quality of light sources and the changes in the lighting conditions. Technological advance has led to an increase in the development of intelligent systems that are permanently connected to the Internet and that allow access to real time-data. Smart lighting systems have become a subject of great interest given their potential in different application areas, such as optimization for object reflectance and damage reduction to artwork. It has become necessary to develop new sensors that are aligned with the technological needs, that are easily integrated into IoT (Internet of Things) or smart lightning systems, and that allow estimating lighting quality measurements in real time. Here, a low-cost IoT multi-spectral acquisition device with wireless communication is presented. Insights into the overall system design and a validation of its operation is provided to allow reproducibility and independent testing of the proposed device. The device can be used for light source spectrum recovery and estimation of light quality and color rendering measures. The total cost of the device is below 130 USD, and customizability provides a great advantage over commercially available devices.

Portable low-cost IoT hyperspectral acquisition device for indoor/outdoor applications.

In lighting engineering, it has become necessary to develop new acquisition devices aligned with today's technological needs, so that they can be easily integrated with IoT (Internet of things) systems. This allows recording lighting data in real-time either to perform analysis, estimate lighting quality measurements, or interact with intelligent lighting systems. Here a portable low-cost IoT hyperspectral acquisition device is presented, which can be used to perform measurements both indoors and outdoors. Since the device is part of IoT technologies, it has wireless communication and allows raw data to be sent to the cloud or to perform calculations directly within the device to be transmitted later. In addition, information on the hardware general design is provided and the device measurements uniformity is validated using the ASTM G-173-03 solar spectra. The proposed device can be used outdoors since its container is IP67 and it can simultaneously measure incident and diffuse radiation. On the other hand, the recorded data can be used for light source spectrum recovery, and to calculate light quality measurements. The hardware and software are customizable, which is an advantage over commercially available devices. The final cost of the device is 271.95 USD.

Spectral Analysis and Mutual Information Estimation of Left and Right Intracardiac Electrograms during Ventricular Fibrillation.

Ventricular fibrillation (VF) signals are characterized by highly volatile and erratic electrical impulses, the analysis of which is difficult given the complex behavior of the heart rhythms in the left (LV) and right ventricles (RV), as sometimes shown in intracardiac recorded Electrograms (EGM). However, there are few studies that analyze VF in humans according to the simultaneous behavior of heart signals in the two ventricles. The objective of this work was to perform a spectral and a non-linear analysis of the recordings of 22 patients with Congestive Heart Failure (CHF) and clinical indication for a cardiac resynchronization device, simultaneously obtained in LV and RV during induced VF in patients with a Biventricular Implantable Cardioverter Defibrillator (BICD) Contak Renewal IVTM (Boston Sci.). The Fourier Transform was used to identify the spectral content of the first six seconds of signals recorded in the RV and LV simultaneously. In addition, measurements that were based on Information Theory were scrutinized, including Entropy and Mutual Information. The results showed that in most patients the spectral envelopes of the EGM sources of RV and LV were complex, different, and with several frequency peaks. In addition, the Dominant Frequency (DF) in the LV was higher than in the RV, while the Organization Index (OI) had the opposite trend. The entropy measurements were more regular in the RV than in the LV, thus supporting the spectral findings. We can conclude that basic stochastic processing techniques should be scrutinized with caution and from basic to elaborated techniques, but they can provide us with useful information on the biosignals from both ventricles during VF.

Awareness of hypoglycemia and spectral analysis of heart rate variability in type 1 diabetes.

AIMS: To investigate the relationship of unawareness of hypoglycemia with spectral analysis of heart rate variability (HRV) and clinical variables in type 1 diabetes (T1D) individuals. METHODS: Participants with type 1 diabetes mellitus (type 1 diabetes) were prospectively assessed for hypoglycemia awareness using the Pedersen-Bjergaard method and were classified as normal hypoglycemia awareness, impaired hypoglycemia awareness and hypoglycemia unawareness. Indices of HRV in frequency domain were evaluated and Ewing tests were used for the diagnosis of cardiovascular autonomic neuropathy (CAN). RESULTS: Ninety-eight participants with T1D (mean age 26 years, average diabetes duration 13 years, and mean HbA1c 8.4%) were included in this study. The prevalence of hypoglycemia unawareness was 28%. No significant difference was observed on the prevalence of CAN among groups of different hypoglycemia awareness (p = 0.740). On regression analyses, abnormal results of HRV in frequency domain were not associated with unawareness of hypoglycemia. On univariable regression analysis, age, diabetes duration and estimated creatinine clearance were associated with unawareness of hypoglycemia. CONCLUSION: CAN as assessed by Ewing tests and spectral analysis of HRV is not associated with unawareness of hypoglycemia. There is association of age, diabetes duration and renal deficit with unawareness of hypoglycemia.

The prefrontal cortex conscious and unconscious response to social/emotional facial expressions involve sex, hemispheric laterality, and selective activation of the central cardiac modulation.

The human prefrontal cortex (PFC) processes complex sensory information for the elaboration of social behaviors. The non-invasive neuroimaging technique near-infrared spectroscopy (NIRS) identifies hemodynamic changes and concentration of oxygenated (HbO2) and deoxygenated (HHb) hemoglobin in the cerebral cortex. We studied the responses detected by NIRS in the right and left PFC activation of 28 participants (n = 14 adult young females and males) while processing social/emotional facial expressions, i.e., in conscious perception of different expressions (neutral, happy, sad, angry, disgust, and fearful) and in unconscious/masked perception of negative expressions (fearful and disgust overlapped by neutral). The power spectral analysis from concomitant ECG signals revealed the sympathetic and parasympathetic modulation of cardiac responses. We found higher HbO2 values in the right PFC of females than in males during, and in the left PFC after, following the conscious perception of the happy face. In males, the left PFC increased and the right PFC decreased HbO2 while viewing the happy expression. In both sexes, HHb values were higher during the masked presentation of disgust than fearful expression, and after the masked presentation of fearful expression than during it. Higher sympathetic and lower parasympathetic activity (LF/ HF components) occurred in females when consciously and unconsciously processing negative emotions (p < 0.05 in all cases). These results demonstrate that the human PFC displays a selective activation depending on sex, hemispheric laterality, attention, time for responding to conscious and unconscious emotionally loaded stimuli with simulataneous centrally modulated cardiovascular responses.

Increased sympathetic cardiac autonomic modulation after two consecutive tilt tests in women with polycystic ovary syndrome / Aumento da modulação autonômica cardíaca simpática após dois testes de inclinação consecutivos em mulheres com síndrome dos ovários policísticos

Abstract Objective The present study aimed to analyze cardiac autonomic modulation via spectral and symbolic analysis of heart rate variability (HRV) in women with polycystic ovary syndrome (PCOS) who were subjected to two consecutive tilt tests. Methods A total of 64 women were selected and divided into 2 groups: control (without PCOS), and PCOS. Concentrations of follicle-stimulating hormone, luteinizing hormone, prolactin, estradiol, homocysteine, sex hormone-binding globulin, thyroid stimulating hormone, fasting insulin, testosterone, androstenedione, and 17-hydroxyprogesterone levels, triglycerides, free androgen index (FAI), and homeostasis assessment model (HOMA-IR) were assessed. Cardiac autonomic modulation was evaluated by spectral and symbolic analyses during two consecutive tilt tests (two moments) and supine moments before, between and after (three moments) the tilt tests. Results Women with PCOS had higher fasting insulin, HOMA-IR indexes, testosterone and FAI. Additionally, we observed that the PCOS group had greater sympathetic autonomic cardiac modulation in supine 2, tilt 1, and supine 3 moments compared with controls. Conclusion Women with PCOS had higher autonomic sympathetic cardiac modulation even after a second tilt test. No adaptation to this provocative test was observed. Spectral analysis was more sensitive for identifying differences between groups than the symbolic analysis.

Resumo Objetivo O presente estudo teve como objetivo analisar a modulação autonômica cardíaca por análise espectral e simbólica da variabilidade da frequência cardíaca (VFC) em mulheres com síndrome dos ovários policísticos (SOP) que foram submetidas a dois testes consecutivos de inclinação. Métodos Um total de 64 mulheres foram selecionadas e divididas em 2 grupos: controle (sem SOP) e SOP. Concentrações de hormônio folículo-estimulante, hormônio luteinizante, prolactina, estradiol, homocisteína, globulina de ligação a hormônios sexuais, hormônio estimulante da tireóide, insulina em jejum, testosterona e androstenediona e níveis de 17-hidroxiprogesterona, triglicerídeos, índice de andrógeno livre (FAI) e homeostase modelo de avaliação (HOMA-IR) foram avaliados. A modulação autonômica cardíaca foi avaliada por análises espectrais e simbólicas durante dois testes de inclinação consecutivos (dois momentos) e momentos supinos antes, entre e após (três momentos) os testes de inclinação. Resultados Mulheres com SOP apresentaram insulina em jejuM, índices HOMA-IR, testosterona e FAI mais altos. Além disso, observamos que o grupo PCOS apresentou maior modulação cardíaca autonômica simpática nos momentos supino 2, inclinado 1 e supino 3 em comparação aos controles. Conclusão Mulheres com SOP apresentaram modulação cardíaca simpática autonômica mais alta mesmo após um segundo teste de inclinação. Nenhuma adaptação a esse teste provocativo foi observada. A análise espectral foi mais sensível para identificar diferenças entre os grupos do que a análise simbólica.