A novel algorithm for the heart rate variability analysis of short-term recordings: Polar representation of respiratory sinus arrhythmia

A new method for the analysis of heart rate variability in short-term recordings is presented which consists of an analysis of the respiratory sinus arrhythmia in the time domain by means of a polar representation. Its main advantage is that it is applicable in experiments in which the respiration of the subject is not controlled. The algorithm is applied to data recorded on two astronauts during the Euromir-95 space mission. Statistical hypothesis tests demonstrate that the presence of a mouthpiece induces an increase of the respiratory sinus arrhythmia amplitude.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Automated breath detection on long-duration signals using feedforward backpropagation artificial neural networks

A new breath-detection algorithm is presented, intended to automate the analysis of respiratory data acquired during sleep. The algorithm is based on two independent artificial neural networks (ANN insp and ANN expi) that recognize, in the original signal, windows of interest where the onset of inspiration and expiration occurs. Postprocessing consists in finding inside each of these windows of interest minimum and maximum corresponding to each inspiration and expiration. The ANN insp and ANN expi correctly determine respectively 98.0% and 98.7% of the desired windows, when compared with 29 820 inspirations and 29 819 expirations detected by a human expert, obtained from three entire-night recordings. Postprocessing allowed determination of inspiration and expiration onsets with a mean difference with respect to the same human expert of (mean ± SD) 34 ± 71 ms for inspiration and 5 ± 46 ms for expiration. The method proved to be effective in detecting the onset of inspiration and expiration in full night continuous recordings. A comparison of five human experts performing the same classification task yielded that the automated algorithm was undifferentiable from these human experts, falling within the distribution of human expert results. Besides being applicable to adult respiratory volume data, the presented algorithm was also successfully applied to infant sleep data, consisting of uncalibrated rib cage and abdominal movement recordings. A comparison with two previously published algorithms for breath detection in respiratory volume signal shows that the presented algorithm has a higher specificity, while presenting similar or higher positive predictive values.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Mathematical assessment of qualitative diagnostic calibration for respiratory inductive plethysmography

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Ventilation-perfusion matching in long-term microgravity

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Optical response of conjugated polymers

We present a simple model for the description of the linear and nonlinear optical response of conjugated polymers, where the electrons are confined in a periodic system composed of anharmonic potential wells. We calculate the optical band gap, the polarizability, and the second hyperpolarizability as a function of the molecular length for the oligomers of thiophene and benzene, adjusting the model parameters to two band-gap measurements. We find them to be in fair agreement with experimental data. Furthermore, the length dependencies are discussed and compared with experimental and theoretical reported values. The model is very suitable for studying the sensitivity of the optical response to conformational disorder. © 1993 The American Physical Society.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Origin of the saturation of the third-order optical nonlinear response of one-dimensional conjugated systems

The coupled quantum oscillator model is applied to the evaluation of conformational effects in thiophene and polyene oligomers. Thermochromism measurements on heptathiophene are presented and modeled. The effect of conformation is also studied in recently published nonlinear optical experiments on polyene oligomers. It is shown that the model accounts for a masterplot which summarizes the length dependence of the optical properties of conjugated molecules. © 1997 Elsevier Science B.V.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Piezoelectric sensor vs. respiratory inductive plethysmograph

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Diaphragm dimensions after single-lung transplantation for emphysema

We used three-dimensional reconstructions obtained with spiral computed tomography to measure total diaphragm surface area (Adi), and the surface area of the dome (Ado) and of the zone of apposition (Aap) of the diaphragm in nine patients with single-lung transplantation (SLT) for emphysema and nine normal subjects matched for age, sex, height, and weight. Measurements were obtained at supine FRC, midinspiratory capacity, and TLC. In the normal subjects, Ado and Adi were greater on the right than on the left side, and the right dome was positioned more cranially than the left one, presumably because of the presence of the liver. Compared with either the ipsilateral side in the controls or the native side in the patients, Ado was smaller on the transplanted side because the mediastinum was shifted toward the graft. Adi showed a similar trend. On the other hand, the radius of curvature of the dome in the coronal and sagittal planes was similar on the side of the graft and on the ipsilateral side in the controls. In conclusion, we found that after SLT for emphysema, diaphragm configuration comes back to normal but Ado, and with it Adi, remain smaller than in normal subjects because the mediastinum is displaced toward the graft.Journal Articleinfo:eu-repo/semantics/publishe

Telescience operation in the belgian user support and operation center

info:eu-repo/semantics/publishe

A telemanagement system for home follow-up of respiratory patients

SCOPUS: ar.jinfo:eu-repo/semantics/publishe