Md Aktaruzzaman

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Mn(3)O(4) nanoparticles with diameter ca. 10nm were synthesized by the forced hydrolysis of Mn(II) acetate at 80 degrees C. The X-ray diffraction (XRD), Fourier transform infra red (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques were employed to study structural features and chemical composition of the(More)
AIMS Dynamics of cardiovascular series may be explored with non-linear techniques. It is unknown if the arterial pressure irregularity commonly observed in patients with atrial fibrillation (AF) might be further increased by a sympathetic stimulus such as orthostatic tilt. METHODS AND RESULTS Twenty patients (62 ± 14 years, 15 men) were recruited for the(More)
Aims: Sample Entropy (SampEn) is a powerful approach for characterizing heart rate variability regularity. On the other hand, autoregressive (AR) models have been employed for maximum-entropy spectral estimation for more than 40 years. The aim of this study is to explore the feasibility of a parametric approach for SampEn estimation through AR models. We(More)
The concurrent usage of actigraphy and heart rate variability (HRV) for sleep efficiency quantification is still matter of investigation. This study compared chest (CACT) and wrist (WACT) actigraphy (actigraphs positioned on chest and wrist, respectively) in combination with HRV for automatic sleep vs wake classification. Accelerometer and ECG signals were(More)
Labor exposes the fetus to repetitive transient hypoxic stress. We assessed whether such events modify the regularity of the fetal inter-beat interval series (fRR), using an in-vivo near-term sheep model, by means of entropy measures. Umbilical cord occlusions (UCO), from partial to complete, were applied to 7 near-term pregnant sheep. Fetal blood samples(More)
Lempel-Ziv Complexity (LZC) has been demonstrated to be a powerful complexity measure in several biomedical applications. During sleep, it is still not clear how many samples are required to ensure robustness of its estimate when computed on beat-to-beat interval series (RR). The aims of this study were: i) evaluation of the number of necessary samples in(More)
OBJECTIVE A critical point in any definition of entropy is the selection of the parameters employed to obtain an estimate in practice. We propose a new definition of entropy aiming to reduce the significance of this selection. METHODS We call the new definition Bubble Entropy. Bubble Entropy is based on Permutation Entropy, where the vectors in the(More)
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