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Approximate entropy

Quynhgiao N Nguyen, Charles W Bauschlicher, Dwight L Myers, Nathan S Jacobson, Elizabeth J Opila
The volatility of titanium dioxide (TiO2) in water vapor-containing environments at elevated temperatures is studied with both quantum chemical composite methods and the experimental transpiration method. The geometry and harmonic vibrational frequencies of TiO(OH)2(g) and Ti(OH)4(g) were computed using the coupled-cluster singles and doubles method with a perturbative correction for connected triple substitutions [CCSD(T)]. The B3LYP density functional theory was used to compute corrections to the harmonic approximations...
November 13, 2017: Journal of Physical Chemistry. A
Supreeth Prajwal Shashikumar, Qiao Li, Gari D Clifford, Shamim Nemati
Sepsis, a dysregulated immune-mediated host response to infection, is the leading cause of morbidity and mortality in critically ill patients. Indices of heart rate variability and complexity (such as entropy) have been proposed as surrogate markers of Neuro-immune system dysregulation with diseases such as sepsis. However, these indices only provide an average, one dimensional description of complex neuro-physiological interactions. We propose a novel multiscale network construction and analysis method for multivariate physiological time series, and demonstrate its utility for early prediction of sepsis...
November 1, 2017: Physiological Measurement
Haoshi Zhang, Lan Tian, Huiyang Lu, Ming Zhou, Haiqing Zou, Peng Fang, Fuan Yao, Guanglin Li
Continuous electrocardiogram (ECG) monitoring is significant for prevention of heart disease and is becoming an important part of personal and family health care. In most of the existing wearable solutions, conventional metal sensors and corresponding chips are simply integrated into clothes and usually could only collect few leads of ECG signals that could not provide enough information for diagnosis of cardiac diseases such as arrhythmia and myocardial ischemia. In this study, a wearable 12-lead ECG acquisition system with fabric electrodes was developed and could simultaneously process 12 leads of ECG signals...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
G Valenza, A Duggento, L Passamonti, S Diciotti, C Tessa, N Toschi, R Barbieri
While estimates of complex heartbeat dynamics have provided effective prognostic and diagnostic markers for a wide range of pathologies, brain correlates of complex cardiac measures in general and of complex sympatho-vagal dynamics in particular are still unknown. In this study we combine resting state functional Magnetic Resonance Imaging (fMRI) and physiological signal acquisition from 34 healthy subjects selected from the Human Connectome Project (HCP) repository with inhomogeneous point-process approximate and sample heartbeat entropy measures (ipApEn and ipSampEn) to investigate brain areas involved in complex cardiovascular control...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Nikhil S Padhye, Nancy Bergstrom, Mary Pat Rapp, LuAnn Etcher, Nancy S Redeker
Activity levels in nursing home residents were measured with accelerometers over one week as part of a multicenter randomized controlled trial, and complexity of the resulting activity patterns were characterized. Among 813 study participants on whom activity data had been collected, 16 participants developed pressure ulcers by the end of the study. The fractal dimension D0 of the activity series was lower (p=0.039) in residents who developed pressure ulcers than in controls matched on the basis of race, randomization group, score on the Braden scale, and diagnoses of cardiovascular disease and dementia...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Carlos Granero-Belinchon, Stephane G Roux, Nicolas B Garnier, Patrice Abry, Muriel Doret
The analysis of the temporal dynamics in intrapartum fetal heart rate (FHR), aiming at early detection of fetal acidosis, constitutes an intricate signal processing task, that continuously receives significant research efforts. Entropy and entropy rates, envisaged as measures of complexity, often computed via popular implementations referred to as Approximate Entropy (ApEn) or Sample Entropy (SampEn), have regularly been reported as significant features for intrapartum FHR analysis. The present contribution aims to show how mutual information enhances characterization of FHR temporal dynamics and improves fetal acidosis detection performance...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Xiangjun Sun, Huihui Li, Wenjing Du, Wenmin Chen, Fang Zhou, Lei Wang
Through the investigation of the difference of approximate entropy (ApEn) and Hilbert-Huang Transform Marginal spectrum entropy (HHTMSEn) of the Electroencephalogram (EEG) signals of specific low back pain (SLBP) patients before and after the massage, we wanted to reveal the impact of the massage in the brain, and provided the basis for the massage treatment of SLBP patients. We recruited twenty-six SLBP patients and collected their spontaneous EEG signals before and after the massage. Firstly, we analyzed the ApEn and HHTMSEn of fourteen channels before and after the massage, and results showed that values of ApEn and HHTMSEn after the massage were less than the values before the massage significantly...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Xiaohua Douglas Zhang
Recently, the rapid development of large data storage technologies, mobile network technology, and portable medical devices makes it possible to measure, record, store, and track analysis of biological dynamics. Portable noninvasive medical devices are crucial to capture individual characteristics of biological dynamics. The wearable noninvasive medical devices and the analysis/management of related digital medical data will revolutionize the management and treatment of diseases, subsequently resulting in the establishment of a new healthcare system...
2017: Advances in Experimental Medicine and Biology
Jun Young Chung, Jack F Douglas, Christopher M Stafford
We investigate the relaxation dynamics of thin polymer films at temperatures below the bulk glass transition Tg by first compressing polystyrene films supported on a polydimethylsiloxane substrate to create wrinkling patterns and then observing the slow relaxation of the wrinkled films back to their final equilibrium flat state by small angle light scattering. As with recent relaxation measurements on thin glassy films reported by Fakhraai and co-workers, we find the relaxation time of our wrinkled films to be strongly dependent on film thickness below an onset thickness on the order of 100 nm...
October 21, 2017: Journal of Chemical Physics
Pingjie Huang, Ke Wang, Dibo Hou, Jian Zhang, Jie Yu, Guangxin Zhang
The contaminant detection in water distribution systems is essential to protect public health from potentially harmful compounds resulting from accidental spills or intentional releases. As a noninvasive optical technique, ultraviolet-visible (UV-Vis) spectroscopy is investigated for detecting contamination events. However, current methods for event detection exhibit the shortcomings of noise susceptibility. In this paper, a new method that has less sensitivity to noise was proposed to detect water quality contamination events by analyzing the complexity of the UV-Vis spectrum series...
August 1, 2017: Applied Optics
Ahmet Gul, Burak Erman
Prediction of peptide binding on specific human leukocyte antigens (HLA) has long been studied with successful results. We herein describe the effects of entropy and dynamics by investigating the binding stabilities of 10 nanopeptides on various HLA Class I alleles using a theoretical model based on molecular dynamics simulations. The fluctuational entropies of the peptides are estimated over a temperature range of 310-460 K. The estimated entropies correlate well with experimental binding affinities of the peptides: Peptides that have higher binding affinities have lower entropies compared to non-binders, which have significantly larger entropies...
October 16, 2017: Physical Biology
Juan López-Pascual, Álvaro Page, Pilar Serra-Añó
This cross-sectional study analyzed the influence of chronic shoulder pain (CSP) on movement variability/kinematics during humeral elevation, with the trunk and elbow motions constrained to avoid compensatory strategies. For this purpose, 37 volunteers with CSP as the injured group (IG) and 58 participants with asymptomatic shoulders as the control group (CG) participated in the study. Maximum humeral elevation (Emax), maximum angular velocity (Velmax), variability of the maximum angle (CVEmax), functional variability (Func_var), and approximate entropy (ApEn) were calculated from the kinematic data...
October 13, 2017: Journal of Motor Behavior
Jamie Pethick, Samantha L Winter, Mark Burnley
The temporal structure, or complexity, of muscle torque output decreases with neuromuscular fatigue. The role of central fatigue in this process is unclear. PURPOSE: We tested the hypothesis that caffeine administration would attenuate the fatigue-induced loss of torque complexity. METHODS: Eleven healthy participants performed intermittent isometric contractions of the knee extensors to task failure at a target torque of 50% maximal voluntary contraction (MVC), with a 60% duty factor (6 s contraction, 4 s rest), 60 min after ingesting 6 mg·kg caffeine or a placebo...
October 3, 2017: Medicine and Science in Sports and Exercise
Chandan Karmakar, Radhagayathri K Udhayakumar, Peng Li, Svetha Venkatesh, Marimuthu Palaniswami
Distribution entropy (DistEn) is a recently developed measure of complexity that is used to analyse heart rate variability (HRV) data. Its calculation requires two input parameters-the embedding dimension m, and the number of bins M which replaces the tolerance parameter r that is used by the existing approximation entropy (ApEn) and sample entropy (SampEn) measures. The performance of DistEn can also be affected by the data length N. In our previous studies, we have analyzed stability and performance of DistEn with respect to one parameter (m or M) or combination of two parameters (N and M)...
2017: Frontiers in Physiology
Congcong Ma, Wenfeng Li, Raffaele Gravina, Jingjing Cao, Qimeng Li, Giancarlo Fortino
As a sedentary lifestyle leads to numerous health problems, it is important to keep constant motivation for a more active lifestyle. A large majority of the worldwide population, such as office workers, long journey vehicle drivers and wheelchair users, spends several hours every day in sedentary activities. The postures that sedentary lifestyle users assume during daily activities hide valuable information that can reveal their wellness and general health condition. Aiming at mining such underlying information, we developed a cushion-based system to assess their activity levels and recognize the activity from the information hidden in sitting postures...
October 3, 2017: Sensors
Vahid Rostami, PierGianLuca Porta Mana, Sonja Grün, Moritz Helias
Pairwise maximum-entropy models have been used in neuroscience to predict the activity of neuronal populations, given only the time-averaged correlations of the neuron activities. This paper provides evidence that the pairwise model, applied to experimental recordings, would produce a bimodal distribution for the population-averaged activity, and for some population sizes the second mode would peak at high activities, that experimentally would be equivalent to 90% of the neuron population active within time-windows of few milliseconds...
October 2017: PLoS Computational Biology
Minmin Miao, Hong Zeng, Aimin Wang, Fengkui Zhao, Feixiang Liu
Electroencephalogram (EEG)-based motor imagery (MI) brain-computer interface (BCI) has shown its effectiveness for the control of rehabilitation devices designed for large body parts of the patients with neurologic impairments. In order to validate the feasibility of using EEG to decode the MI of a single index finger and constructing a BCI-enhanced finger rehabilitation system, we collected EEG data during right hand index finger MI and rest state for five healthy subjects and proposed a pattern recognition approach for classifying these two mental states...
September 2017: Review of Scientific Instruments
Trine Krogh-Madsen, Louise Kold Taylor, Anne D Skriver, Peter Schaffer, Michael R Guevara
The transmembrane potential is recorded from small isopotential clusters of 2-4 embryonic chick ventricular cells spontaneously generating action potentials. We analyze the cycle-to-cycle fluctuations in the time between successive action potentials (the interbeat interval or IBI). We also convert an existing model of electrical activity in the cluster, which is formulated as a Hodgkin-Huxley-like deterministic system of nonlinear ordinary differential equations describing five individual ionic currents, into a stochastic model consisting of a population of ∼20 000 independently and randomly gating ionic channels, with the randomness being set by a real physical stochastic process (radio static)...
September 2017: Chaos
Pablo M Piaggi, Michele Parrinello
We introduce a new fingerprint that allows distinguishing between liquid-like and solid-like atomic environments. This fingerprint is based on an approximate expression for the entropy projected on individual atoms. When combined with local enthalpy, this fingerprint acquires an even finer resolution and it is capable of discriminating between different crystal structures.
September 21, 2017: Journal of Chemical Physics
Rui Sun, Wan-Wa Wong, Jing Wang, Raymond Kai-Yu Tong
Entropy-based algorithms have been suggested as robust estimators of electroencephalography (EEG) predictability or regularity. This study aimed to examine possible disturbances in EEG complexity as a means to elucidate the pathophysiological mechanisms in chronic stroke, before and after a brain computer interface (BCI)-motor observation intervention. Eleven chronic stroke subjects and nine unimpaired subjects were recruited to examine the differences in their EEG complexity. The BCI-motor observation intervention was designed to promote functional recovery of the hand in stroke subjects...
2017: Frontiers in Human Neuroscience
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