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This paper deals with the diagnosis of intellectual precocity in gifted children (GC) cases. The P300 component is usually used for giftedness identification. By the use of empirical mode decomposition (EMD), a significant P300 detection... more
This paper deals with the diagnosis of intellectual precocity in gifted children (GC) cases. The P300 component is usually used for giftedness identification. By the use of empirical mode decomposition (EMD), a significant P300 detection is obtained through electroencephalogram signals (EEG). The novelty of the proposed work is to speed up the intellectual ability characterization based on statistical features extraction from P300 response. In order to get an optimized number of estimated information, a selection technique based on the characterization degree criterion (CD-J) is then introduced. This allows a considerably computing time decreasing and an excessive performance of the achieved results. Besides that, the proposed analysis method is applied on (GC) dataset, covering a parental relationship. Compared to the previous works, the proposed approach seems to be promising and useful for the characterization children and their diagnostic improvement.
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Research Interests: Mathematics, Computer Science, Signal Processing, Digital Signal Processing, Biomedical signal and image processing, and 11 moreElectrocardiography, Electrocardiology, Estimation, Exercise Testing, Scaling, Gaussian, Electrocardiogram, Parametric Statistics, Exercise Test, Electrocardiogram (ECG) Signals, and Electrocardiography Digital Signal Processing
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Research Interests: Statistics and Jitter
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Aging is coupled with alterations of heart rate and heart rate variability (HRV), together with increased incidence of arrhythmias and sudden cardiac death. But whether changes of sinus rhythm properties of the aged heart correlate with... more
Aging is coupled with alterations of heart rate and heart rate variability (HRV), together with increased incidence of arrhythmias and sudden cardiac death. But whether changes of sinus rhythm properties of the aged heart correlate with enhanced occurrence of ventricular ectopic discharge remains unclear. Thus, we studied the effects of aging on heart rate, HRV, and occurrence of premature ventricular complexes (PVCs) in aging C57Bl/6 mice. Electrocardiograms (ECG) were obtained in male and female conscious mice at ~4, ~12, ~18, and ~24 months of age (n=37-66). Heart rate was preserved at ~4, ~12, and ~18 months (729±30, 730±22, and 725±20 bpm) and reached a minimum at ~24 months (708±37 bpm). Standard deviation of RR intervals, an indicator of HRV, was maximal at ~4 months (3.5±1.7 ms) and was reduced at ~12, ~18, and ~24 months (2.6±1.5, 2.5±1.3, and 2.6±1.3 ms). By frequency domain analysis, high-frequency components of RR interval variations, indicative of parasympathetic influence, were preserved with aging. In contrast, low frequency components, comprising the influence of sympathetic and parasympathetic axis, were maximal in young animals and progressively decrease at ~12, ~18, and ~24 months. PVCs were observed in only 3% of mice at ~4 months, a fraction that increased to 11%, 10%, and 22% at ~12, ~18, and ~24 months, respectively. For each age interval, heart rate and HRV parameters for animals with PVCs were distributed within the range observed in mice not experiencing ventricular ectopy. Moreover, for animals with PVCs, parameters of HRV before the occurrence of ectopic beats were comparable to those observed during undisturbed sinus rhythm, although a tendency for lower heart rate was seen. To address the role of the autonomic nervous system on incidence of ectopic events, ECGs were collected before and after block of the sympathetic and parasympathetic axis in mice at ~4 months (n=30) and ~24 months (n=26). This intervention reduced heart rate in both groups of animals and attenuated HRV exclusively in young. Moreover, combine autonomic block decreased incidence of PVCs by 50% and 57% in young and old animals, respectively. Collectively, these results suggest that occurrence of ventricular ectopy does not correlate with heart rhythm dynamics.
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Time to task failure during high-intensity, exhaustive cycling exercise might coincide with a severe degree of peripheral fatigue, which is never voluntarily exceeded by the exercising human (i.e. a “critical threshold”). However, data... more
Time to task failure during high-intensity, exhaustive cycling exercise might coincide with a severe degree of peripheral fatigue, which is never voluntarily exceeded by the exercising human (i.e. a “critical threshold”). However, data showed that it is possible to improve performance time during cycling time trial (TT), by misleading participants into believing they are racing against a virtual avatar reproducing a previous TT when, in fact, power output was greater (i.e. deceptive TT). The neuromuscular consequences underpinning this performance improvement remains to be determined. Therefore, the present study aimed to investigate the influence of deceptive TTs on end-exercise peripheral and central fatigue. Ten participants performed, on separate days, one maximal 5km TT (5KCTRL) and three deceptive 5km TTs, during which they had to strictly adjust their pace to match the one of a virtual pacer. Whilst participants were informed that the virtual pacer reproduced the pattern of power output measured during 5KCTRL, which was true in only one session (5K100%), power output was in fact 5% (5K105%) and 10% (5K110%) greater in two other sessions. Maximal voluntary contraction (MVC) and peripheral fatigue were quantified via changes in pre- to post-exercise isometric quadriceps force and potentiated quadriceps twitch force (QTW) as evoked by supramaximal electrical stimulation of the femoral nerve, respectively. Central fatigue was estimated via changes in pre- to post-exercise quadriceps voluntary activation (VA). Power output (229±64W vs 219±61W, P 0.25) to improve power output (223±60W) and performance time (9.12±1.1min) compared to 5K100%. Following 5K110%, reduction in MVC (-40±14%), VA (-16±9%) and QTW (-51±8%) were not different compared to 5K100% (P>0.23). Our data showed that performance improvement during a deceptive TT is limited to small increments in power output and occurred at the expense of a centrally-mediated reduction in the muscle force generating capacity. This rise in central fatigue might assure that muscle activation does not surpass a level that would cause a further accumulation of peripheral fatigue beyond an invariable level.
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Notch1 receptor signaling is active in the heart during embryonic development, is progressively silenced after birth, and it is partly restored in the adult myocardium following ischemic damage, a condition characterized by occurrence of... more
Notch1 receptor signaling is active in the heart during embryonic development, is progressively silenced after birth, and it is partly restored in the adult myocardium following ischemic damage, a condition characterized by occurrence of arrhythmias. We previously reported that inducible overexpression of Notch1 intracellular domain (gain-of-function, NGoF) in adult mouse cardiomyocytes alters ionic currents and action potential profile. But the consequences of Notch1 signaling activation on electrical properties and arrhythmogenicity of the entire heart remain to be defined. For this purpose, electrocardiograms were obtained in NGoF (n=25) and corresponding control (Ctrl, n=13) mice in the conscious state, over a 10 min period. Electrical signals were obtained at baseline and following administration of an arrhythmogenic cocktail (120 mg/kg BW caffeine and 2 mg/kg BW epinephrine) to test the propensity of these animals to develop electrical disturbances. Moreover, information was also obtained in mice with inducible Notch1 gene deletion for complete silencing of Notch1 signaling (Notch1 loss-of-function, NLoF, n=5). At baseline, heart rate and QT interval duration were comparable in NGoF (689±30 bpm; 49±2 ms), Ctrl (703±29 bpm; 48±1 ms), and NLoF (697±50 bpm; 48±1 ms) animals. Only a small fraction (~8%) of NGoF mice presented isolated premature ventricular complexes (PVCs) or junctional rhythm, but these events were not observed in Ctrl and NLoF mice. Administration of the arrhythmogenic cocktail induced PVCs in the majority of Ctrl (~56%) and NLoF (~60%) mice and in almost all NGoF animals (~92%). Also recurrent PVCs (≥10/10 min) were 1.7-2.1-fold higher in NGoF mice, with respect to NLoF and Ctrl. Importantly, 77% of NGoF mice developed ventricular tachycardia (VT), whereas VT occurrence was attenuated in Ctrl (56%) and NLoF (~40%) animals. Incidence of sustained VT was 1.7-fold higher in NGoF mice, with respect to Ctrl. Similarly, bidirectional VT was higher in NGoF (~62%), with respect to Ctrl (~52%) and NLoF (~40%). Thus, Notch signaling activation in the heart of experimental animals tends to enhance the occurrence of electrical disturbances, a factor that may be involved in the arrhythmogenic behavior of the post-infarcted myocardium.
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Research Interests: Hysteresis and Phenomenon
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Heart rate variability (HRV) is an index of cardiovascular health and reflects the ability of the heart to adjust sinus rhythm in response to autonomic regulation, a process affected by age. Importantly, Na channels have emerged as key... more
Heart rate variability (HRV) is an index of cardiovascular health and reflects the ability of the heart to adjust sinus rhythm in response to autonomic regulation, a process affected by age. Importantly, Na channels have emerged as key components of discharge and conduction of the sino-atrial node, but whether altered Na channels affect HRV remains to be established. Thus, we studied effects of aging and altered Na channels on heart rate and HRV using wild type (WT) mice and mice with phosphomimetic mutation of Na channel Nav1.5 at Ser571 (S571E mice). Electrocardiograms (ECG) were obtained in male conscious mice at ~4, ~12, ~18, and ~24 months of age (n=13-51). The mean RR interval of the ECG was similar in WT mice at ~4, ~12, and ~18 months (83±4, 81±2, 83±2 ms, respectively), but increased at ~24 months (85±5 ms). In contrast, mean RR interval in S571E mice was maximal at ~4 months (86±6 ms) and progressively decreased at ~12 (83±9 ms), ~18 (79±2 ms), and ~24 months (80±3 ms). St...
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Accurate detection off waves during atrial flutter is difficult. However,f waves contain information on the pathology and are useful for non-invasive diagnosis. The setup and difficulties off wave detection lends itself to the use of... more
Accurate detection off waves during atrial flutter is difficult. However,f waves contain information on the pathology and are useful for non-invasive diagnosis. The setup and difficulties off wave detection lends itself to the use of statistical signal detection techniques. Real-life constraints can be modeled in the signal observation using several parameters in order to produce signal detectors with good performance. Several detectors were developed and tested using real 12-lead ECG recordings with manually annotated f wave markers available. At the end, a simple detector is obtained with relatively good detection performance (AUC= 0.89, (Se, Sp) = (0.84,0.81)) and a threshold is available for use in automatic detection off waves.
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Introduction We determined the recovery from neuromuscular fatigue in six professional (PRO) and seven moderately trained (MOD) cyclists after repeated cycling time trials of various intensities/durations. Method Participants performed... more
Introduction We determined the recovery from neuromuscular fatigue in six professional (PRO) and seven moderately trained (MOD) cyclists after repeated cycling time trials of various intensities/durations. Method Participants performed two 1-min (1minTT) or two 10-min (10minTT) self-paced cycling time trials with 5 min of recovery in between. Central and peripheral fatigue were quantified via preexercise to postexercise (15-s through 15-min recovery) changes in voluntary activation (VA) and potentiated twitch force. VA was measured using the interpolated twitch technique, and potentiated twitch force was evoked by single (QTsingle) and paired (10-Hz (QT10) and 100-Hz (QT100)) electrical stimulations of the femoral nerve. Results Mean power output was 32%–72% higher during all the time trials and decreased less (−10% vs −13%) from the first to second time trial in PRO compared with MOD (P < 0.05). Conversely, exercise-induced reduction in QTsingle and QT10/QT100 was significantly ...
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ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head... more
ABSTRACT The purpose of this study was to compare lower limb muscle activity between physically active and inactive individuals during whole-body vibration exercises. Additionally, transmissibility of the vertical acceleration to the head was quantified. 30 active and 28 inactive participants volunteered to stand in a relaxed (20°) and a squat (60°) position on a side-alternating WBV platform that induced vibrations at 16 Hz and 4 mm amplitude. Surface electromyography (sEMG) was measured in selected lower limb muscles and was normalized to the corresponding sEMG recorded during a maximal voluntary contraction. The vertical acceleration on the head was evaluated and divided by the vertical platform acceleration to obtain transmissibility values. Control trials without vibration were also assessed. The outcomes of this study showed that (1) WBV significantly increased muscle activity in the active (absolute increase: +7%, P &lt;0.05) and inactive participants (+8%, P &lt;0.05), (2) with no differences in sEMG increases between the groups (P&gt;0.05). However, (3), transmissibility to the head was greater in the active (0.080) than the inactive participants (0.065, P &lt;0.05). In conclusion, inactive individuals show similar responses in sEMG due to WBV as their active counterparts, but are at lower risk for potential side-effects of vibration exposure.