Description of the idealized bed roughness effects on tracer transport in water flumes by applying the strange attractor multifractal analysis

River hydrodynamicsTurbulent open channel flow and transport phenomen

Electroencephalogram background activity characterization with Detrended Moving Average in Alzheimer's disease patients

The aim of this study was to analyse the electroencephalogram (EEG) background activity in Alzheimer's disease (AD) with the Detrended Moving Average (DMA) method, a new approach to quantify correlation properties in non-stationary signals with underlying trends. EEGs were recorded from the 19 scalp loci of the international 10-20 system in 11 AD patients and 11 age-matched controls. Our results showed two scaling regions in all subjects' channels, with a clear bend when their corresponding slopes (alpha(1) and alpha(2)) were distinctly different. With the exception of electrode T4, the alpha(1) values were lower in control subjects than in AD patients, with significant differences at TS, P3, P4 and O1 (p < 0.01, Student's t-test). On the other hand, alpha(2) values were higher in control subjects than in AD patients, with significant differences only at F4. Furthermore, we evaluated the ability of alpha(2) to discriminate AD patients from control subjects at these electrodes using ROC plots. We obtained a maximum accuracy of 81.82% at O1 with alpha(1) and at F4 with alpha(2). These findings suggest that the scaling behaviour of the EEG is sensitive to AD and that the DMA method could help to increase our insight into brain dysfunction in AD

Using 222Rn to identify and quantify groundwater inflows to the Mundo River (SE Spain)

Groundwater discharge to the Mundo River (SE, Spain) has been investigated from 2011 to 2013 by means of 222Rn activities in river water and groundwater. Starting nearby the river source, some 50km of river channel have been studied. The Mundo River is located in the water stressed region of the Segura River Basin. Identifying and quantifying groundwater discharge to rivers is essential for the Hydrological Plan of the Segura Basin Authority. Four main areas of groundwater discharge to the river have been identified by means of 222Rn. Moreover, groundwater fluxes have been quantified using radon activities and, when possible, have been validated with chloride mass balances. The uncertainty range (±2σ) of all water balances has also been assessed. Groundwater discharge (QGW) values estimated by radon mass balances (RMB) and chloride mass balances (CMB) were similar in the river tracts and/or dates in which surface inputs from tributaries were null or negligible. This adds confidence to the QGW values estimated by RMB in the reaches were CMB could not be performed due to the existence of ungauged surface inputs, as is the case of the upper basin of the Mundo River, as well as to the applicability of the method to similar situations. Quantification of groundwater discharge allowed identifying Ayna zone as the main gaining reach of the studied area, with up to 29,553±8667m3day-1 in year 2011. Overall, the total QGW estimated by means of RMB for the studied area was 8-16% of the total river flow. The results are coherent with the meteorological conditions of the study period (average rainfall around 450mm/y) and also with the undisturbed situation of the aquifers discharging to the Mundo River in the considered area.Fil: Ortega Ormaechea, Lucia. Universidad Politécnica de Cartagena; España. Universidad Nacional del Centro de la Provincia de Buenos Aires. Rectorado. Instituto de Hidrología de Llanuras-Sede Azul. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Instituto de Hidrología de Llanuras-Sede Azul; ArgentinaFil: Manzano, M.. Universidad Politécnica de Cartagena; EspañaFil: Custodio, E.. Universidad Politecnica de Catalunya; EspañaFil: Hornero, J.. Instituto Geológico y Minero de España; EspañaFil: Rodríguez Arévalo, J.. Centro de Estudios y Experimentación de Obras Públicas; Españ

Parallel Study on Surface and Invasive Recordings Across Catheter Ablation Steps of Paroxysmal Atrial Fibrillation

[EN] Catheter ablation (CA) is the star treatment of atrial fibrillation (AF). However, important issues regarding its procedure have only been superficially explored. While universal CA effect is assessed, the role of right (RPVI) and left pulmonary vein isolation (LPVI) is ignored. Although coronary sinus (CS) is the prevailing CA reference, how CS itself is modified by CA is unknown. This work evaluates the effect of each ablation step on the atrial substrate and CS funtion. Five-minute lead II and bipolar CS recordings of 29 patients undergoing paroxysmal AF CA were acquired before CA, after LPVI and after RPVI (end of CA). Separate lead II and CS analysis was performed. Duration, amplitude, area and slope rate were calculated for each surface and invasive activation, then signal-averaged. Dispersion, morphology variability (MV) and time-domain heart-rate variability (HRV) features were also calculated. Non-parametric tests were recruited to compare each feature among all and in pairs of different ablation steps with Bonferroni correction. Variation of each feature was calculated in percentages. In surface recordings, duration was significantly shortened after LPVI (¿= -13%, p=0.001) and HRV showed a trend for attenuation (¿+73%, p<0.04S), tending to decrease after RPVI (¿< -33%, p<0.064). Higher dispersion in variations was observed in CS than surface recordings. LPVI causes major alterations in atrial substrate, more prominently observed from lead II analysis. Notwithstanding, HRV variations are better illustrated in CS recordings. A combined analysis of both is recommended.Research supported by grants DPI2017-83952-C3 from MINECO/AEI/FEDER UE, SBPLY/17/180501/000411 from JCCLM and AICO/2021/286 from GVA.Vraka, A.; Hornero, F.; Quesada, A.; Ravelli, F.; Alcaraz, R.; Rieta, JJ. (2021). Parallel Study on Surface and Invasive Recordings Across Catheter Ablation Steps of Paroxysmal Atrial Fibrillation. IEEE. 1-4. https://doi.org/10.1109/EHB52898.2021.96576951

Reliability of Local Activation Waves Features to Characterize Paroxysmal Atrial Fibrillation Substrate During Sinus Rhythm

[EN] Analysis of coronary sinus (CS) electrograms (EGMs) is vastly used for the assessment of the atrial fibrillation (AF) substrate. As a catheter consists of five dipoles (distal, mid-distal, medial, mid-proximal, proximal), results may vary upon the employed channel: myocardial contraction and bad contact are unavoidable factors affecting the recording. This work aims to specify the most reliable channels in catching AF dynamics, using 44 multichannel bipolar CS recordings in sinus rhythm (SR) of paroxysmal AF with 1-5 minutes duration. Local activation waves (LAWs) were detected and main features obtained: duration, amplitude, area and correlation between dominant morphologies of each channel. Analysis was performed with Kruskal-Wallis test for multichannel comparison and Mann-Whitney U-test for pairs of channels and comparison between one and the remaining channels, using Bonferroni correction. Median values were calculated. Distal channel presented the highest alteration in LAWs features, being the least correlated channel (82.84 - 88.31%) with the lowest amplitude and area (p(max) < 0.01). Contrastly, medial and mid-proximal channels showed the most robust LAW characteristics, with very high correlation (94.53%) and high area and amplitude values (p(max) < 0.02 and p(max) < 0.07, respectively) and their analysis is recommended for AF substrate characterization during SRResearch supported by grants DPI2017-83952-C3 from MINECO/AEI/FEDER UE, SBPLY/17/180501/000411 from JCCLM and AICO/2019/036 from GVA.Vraka, A.; Hornero, F.; Quesada, A.; Faes, L.; Alcaraz, R.; Rieta, JJ. (2020). Reliability of Local Activation Waves Features to Characterize Paroxysmal Atrial Fibrillation Substrate During Sinus Rhythm. IEEE. 1-4. https://doi.org/10.22489/CinC.2020.166S1

Study on the Stability of CFAEs to Characterize the Atrial Substrate in Atrial Fibrillation

[EN] A variety of indexes has been applied to complex fractionated atrial electrograms (CFAEs) of atrial fibrillation (AF) aimed at characterizing the atrial substrate. However, often the reported results miss the assessment of intra-recording and intra-patient stability of the analyzed data, as well as CFAEs signal quality. This work introduces a study in which Determinism (DET) of Recurrence Quantification Analysis (RQA) and Sample Entropy (SE) have been applied to assess intra-recording and intrapatient stability of 1, 2 and 4 s-length segments CFAEs recorded from patients with paroxysmal and persistent AF using the coefficient of variation (CV). Furthermore, the analyses verified changes introduced by discarding artifacted and noisy CFAE segments. The intra-recording analysis pointed out that discarding segments provoked a significant variation of CV(%) in any segment length both for DET and SE, with deeper decreases for longer segments. Intra-patient stability provided large variations in CV(%) for DET and even bigger for SE at any segment length. In this case discarding segments was useless and CV provided limited variations. Kruskal-Wallis test revealed significant differences in DET and SE values among channels, independently from the discarding process.Research supported by grants DPI2017-83952-C3 from MINECO/AEI/FEDER UE, SBPLY/17/180501/000411 from JCCLM and AICO/2019/036 from GVA.Finotti, E.; Ciaccio, EJ.; Garan, H.; Hornero, F.; Alcaraz, R.; Rieta, JJ. (2020). Study on the Stability of CFAEs to Characterize the Atrial Substrate in Atrial Fibrillation. IEEE. 1-4. https://doi.org/10.22489/CinC.2020.252S1

EEG characterization of the Alzheimer's disease continuum by means of multiscale entropies

Alzheimer's disease (AD) is a neurodegenerative disorder with high prevalence, known for its highly disabling symptoms. The aim of this study was to characterize the alterations in the irregularity and the complexity of the brain activity along the AD continuum. Both irregularity and complexity can be studied applying entropy-based measures throughout multiple temporal scales. In this regard, multiscale sample entropy (MSE) and refined multiscale spectral entropy (rMSSE) were calculated from electroencephalographic (EEG) data. Five minutes of resting-state EEG activity were recorded from 51 healthy controls, 51 mild cognitive impaired (MCI) subjects, 51 mild AD patients (ADMIL), 50 moderate AD patients (ADMOD), and 50 severe AD patients (ADSEV). Our results show statistically significant differences (p-values < 0.05, FDR-corrected Kruskal-Wallis test) between the five groups at each temporal scale. Additionally, average slope values and areas under MSE and rMSSE curves revealed significant changes in complexity mainly for controls vs. MCI, MCI vs. ADMIL and ADMOD vs. ADSEV comparisons (p-values < 0.05, FDR-corrected Mann-Whitney U-test). These findings indicate that MSE and rMSSE reflect the neuronal disturbances associated with the development of dementia, and may contribute to the development of new tools to track the AD progression.This research was supported by European Commission and European Regional Development Fund (FEDER) under project “Análisis y correlación entre el genoma completo y la actividad cerebral para la ayuda en el diagnóstico de la enfermedad de Alzheimer” (Cooperation Programme Interreg V-A Spain-Portugal, POCTEP 2014-2020); by “Ministerio de Ciencia, Innovación y Universidades” and FEDER under projects PGC2018-098214-A-I00 and DPI2017-84280-R; and by “Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Inovação” and FEDER under projects POCI-01-0145-FEDER-007274 and UID/MAT/00144/2013