Recruitment in EEG signals is tested by estimating spectra before and after flash-stimulus onset and comparing them using the F-test. At the stimulus frequency and its harmonics, significant changes are observed, even...
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Recruitment in EEG signals is tested by estimating spectra before and after flash-stimulus onset and comparing them using the F-test. At the stimulus frequency and its harmonics, significant changes are observed, even when using only short data-segments.
In order to improve a classification system for arrhythmia analysis, we developed an algorithm for automatic detection of ventricular response to atrial flutter and fibrillation episodes. As an intermediate step to di...
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In order to improve a classification system for arrhythmia analysis, we developed an algorithm for automatic detection of ventricular response to atrial flutter and fibrillation episodes. As an intermediate step to differentiate these rhythms from the normal, the algorithm detects the presence of sinus P-waves, by analyzing single lead ECG. When P-waves are detected for six successive beats, the rhythm is labeled as normal. If this detection fails, the mean RR interval is computed and analyzed. The rhythm is labelled atrial fibrillation when the mean is between two thresholds. The algorithm identifies as atrial flutter, epochs with high cardiac frequency and low variability. All other rhythms are labeled as abnormal, requiring posterior QRS shape analysis for correct classification. The algorithm was tested with the MIT-BIH Arrhythmia Database.
Presents experimental and theoretical investigations about the effect of mode conversion on the ultrasonic total cross section of polystyrene spheres near the resonance. An ultrasonic continuous-wave was transmitted t...
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Presents experimental and theoretical investigations about the effect of mode conversion on the ultrasonic total cross section of polystyrene spheres near the resonance. An ultrasonic continuous-wave was transmitted through a random medium consisting of a suspension of polystyrene spheres (mean diameter 0.589 mm, standard deviation 0.066 mm) in a solution of water and sugar. The average total cross section of the particle distribution was obtained from measurements of the wave intensity attenuation, for frequency ranges of 0.85 to 3.0 MHz and 5.0 to 6.0 MHz, equivalent to ka ranges (k as the wave number and a as the average radius of the particles) of 1.05 to 3.71 and 6.18 to 7.41, respectively. Experimental results of the total cross section presents a resonant behavior, for ka between 1.07 to 1.38, that is demonstrated to be due to propagation of acoustic shear waves inside the particles
In the search for parameters to quantify clinically significant characteristics of signal shape (for example in evoked potentials), the Fourier Transform has been employed, with the amplitude spectrum having received ...
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ISBN:
(纸本)0780307852
In the search for parameters to quantify clinically significant characteristics of signal shape (for example in evoked potentials), the Fourier Transform has been employed, with the amplitude spectrum having received main attention. However, the phase spectrum appears to be more closely linked to signal shape and principally peak latency. In this paper the still poorly explored relative roles of the two parts of the spectrum in determining transient signal morphology is investigated.
Coherence has been used to study the dependence between EEG derivations as a function of frequency. In order bto arrive at meaningful conclusions the statistics of the estimates must be known and are investigated in t...
This work presents a simple, reliable and accurate calibration technique for pneumotacographs. It is based on a polynomial curve fitting which minimizes the calculated volume error for a set of injections of a calibra...
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A noninvasive technique to measure cardiac output in spontaneously breathing subjects is evaluated. It is based on a differential form of the Fick equation and a partial rebreathing maneuver. Corrections for experimen...
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For the teaching of medicine and dentistry, a system for the development of 3D computer models of the human skull anatomy has been developed, together with a graphics interface for its presentation on screen. The task...
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Ultrasonic medical images is well established as an important diagnostic tool nowadays. Quantitative ultrasonic images, nevertheless, have not reached a clinical use. The cause of this are the peculiar propagation of ...
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In order to characterize ultrasonic (US) transducers, several aspects may be studied, such as the shape of the beam in space, the US intensity along the central axis and the US intensity parallel to the face of the tr...
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