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Approximate entropy

Gregory J O Beran, Joshua D Hartman, Yonaton N Heit
Molecular crystals occur widely in pharmaceuticals, foods, explosives, organic semiconductors, and many other applications. Thanks to substantial progress in electronic structure modeling of molecular crystals, attention is now shifting from basic crystal structure prediction and lattice energy modeling toward the accurate prediction of experimentally observable properties at finite temperatures and pressures. This Account discusses how fragment-based electronic structure methods can be used to model a variety of experimentally relevant molecular crystal properties...
October 18, 2016: Accounts of Chemical Research
Lorenz Kahl, Ulrich G Hofmann
This work compared the performance of six different fatigue detection algorithms quantifying muscle fatigue based on electromyographic signals. Surface electromyography (sEMG) was obtained by an experiment from upper arm contractions at three different load levels from twelve volunteers. Fatigue detection algorithms mean frequency (MNF), spectral moments ratio (SMR), the wavelet method WIRM1551, sample entropy (SampEn), fuzzy approximate entropy (fApEn) and recurrence quantification analysis (RQA%DET) were calculated...
October 7, 2016: Medical Engineering & Physics
Amit Sethi, Nick Stergiou, Tara S Patterson, Carolynn Patten, Lorie G Richards
Temporal structure reveals the potential adaptive strategies employed during upper extremity movements. The authors compared the temporal structure of upper extremity joints under 3 different reaching conditions: preferred speed, fast speed, and reaching with rhythmic auditory cues in 10 individuals poststroke. They also investigated the temporal structure of these 3 reaching conditions in 8 healthy controls to aid in the interpretation of the observed patterns in the poststroke cohort. Approximate entropy (ApEn) was used to measure the temporal structure of the upper extremity joints...
October 11, 2016: Journal of Motor Behavior
Marwène Oumezzine, Aurelian Catalin Galca, Iuliana Pasuk, Cristina Florentina Chirila, Aurel Leca, Victor Kuncser, Liviu Cristian Tanase, Andrei Kuncser, Corneliu Ghica, Mohamed Oumezzine
Epitaxial La0.67Ba0.33Ti0.02Mn0.98O3 (denoted as LBTMO hereafter) thin films of approximately 95 nm thickness were deposited by a pulsed laser deposition technique onto SrTiO3 (STO) (001) substrates. High-resolution X-ray diffraction (HRXRD) and transmission electron microscopy (TEM) investigations revealed that the films are epilayers with a four-fold symmetry around the [001] direction. Cross-sectional TEM and the presence of Pendellosung fringes in the XRD profiles demonstrate smooth interfaces. The STO substrate induces an in-plane compressive strain, which leads to a slight tetragonality of the film structure...
September 27, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Hamidreza Namazi, Amin Akrami, Sina Nazeri, Vladimir V Kulish
An important challenge in brain research is to make out the relation between the features of olfactory stimuli and the electroencephalogram (EEG) signal. Yet, no one has discovered any relation between the structures of olfactory stimuli and the EEG signal. This study investigates the relation between the structures of EEG signal and the olfactory stimulus (odorant). We show that the complexity of the EEG signal is coupled with the molecular complexity of the odorant, where more structurally complex odorant causes less fractal EEG signal...
2016: BioMed Research International
SangMin Choe, Byung-Moon Choi, Yong-Hun Lee, Soo-Han Lee, Eun-Kyung Lee, Ki-Seong Kim, Gyu-Jeong Noh
This study describes the pharmacodynamic interaction between propofol and remifentanil. Sixty patients who were scheduled for elective surgery under general anesthesia (30 males/30 females) were enrolled. Patients were randomly allocated to receive one of 15 combinations of drug levels. Baseline electroencephalograms (EEGs) were recorded for 5 min prior to administering the drugs. Patients received a target-controlled infusion at one of four predefined doses of propofol (high: 3 μg·ml(-1) , medium: 1.5 μg·ml(-1) , low: 0...
October 1, 2016: Clinical and Experimental Pharmacology & Physiology
A Pasturel, N Jakse
It is becoming common practice to consider that the Stokes-Einstein relation D/T~ η (-1) usually works for liquids above their melting temperatures although there is also experimental evidence for its failure. Here we investigate numerically this commonly-invoked assumption for simple liquid metals as well as for their liquid alloys. Using ab initio molecular dynamics simulations we show how entropy scaling relationships developed by Rosenfeld can be used to predict the conditions for the validity of the Stokes-Einstein relation in the liquid phase...
December 7, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Choukri Mekkaoui, Timothy G Reese, Marcel P Jackowski, Stephen F Cauley, Kawin Setsompop, Himanshu Bhat, David E Sosnovik
Purpose To develop a clinically feasible whole-heart free-breathing diffusion-tensor (DT) magnetic resonance (MR) imaging approach with an imaging time of approximately 15 minutes to enable three-dimensional (3D) tractography. Materials and Methods The study was compliant with HIPAA and the institutional review board and required written consent from the participants. DT imaging was performed in seven healthy volunteers and three patients with pulmonary hypertension by using a stimulated echo sequence. Twelve contiguous short-axis sections and six four-chamber sections that covered the entire left ventricle were acquired by using simultaneous multisection (SMS) excitation with a blipped-controlled aliasing in parallel imaging readout...
September 28, 2016: Radiology
Tingting Wu, Alexander J Dufford, Melissa-Ann Mackie, Laura J Egan, Jin Fan
Cognitive control refers to the processes that permit selection and prioritization of information processing in different cognitive domains to reach the capacity-limited conscious mind. Although previous studies have suggested that the capacity of cognitive control itself is limited, a direct quantification of this capacity has not been attempted. In this behavioral study, we manipulated the information rate of cognitive control by parametrically varying both the uncertainty of stimul measured as information entropy and the exposure time of the stimuli...
2016: Scientific Reports
Tiago M Barbosa, Wan Xiu Goh, Jorge E Morais, Mário J Costa
The aim was to examine the variation of linear and nonlinear proprieties of the behaviour in participants with different levels of swimming expertise among the four swim strokes. Seventy-five swimmers were split into three groups (highly qualified experts, experts and non-experts) and performed a maximal 25m trial for each of the four competitive swim strokes. A speed-meter cable was attached to the swimmer's hip to measure hip speed; from which speed fluctuation (dv), approximate entropy (ApEn) and fractal dimension (D) variables were derived...
August 19, 2016: Motor Control
Igor Krasnov, Tilo Seydel, Imke Greving, Malte Blankenburg, Fritz Vollrath, Martin Müller
Spider silk is a material well known for its outstanding mechanical properties, combining elasticity and tensile strength. The molecular mobility within the silk's polymer structure on the nanometre length scale importantly contributes to these macroscopic properties. We have therefore investigated the ensemble-averaged single-particle self-dynamics of the prevailing hydrogen atoms in humid spider dragline silk fibres on picosecond time scales in situ as a function of an externally applied tensile strain. We find that the molecular diffusion in the amorphous fraction of the oriented fibres can be described by a generalized fractional diffusion coefficient Kα that is independent of the observation length scale in the probed range from approximately 0...
September 2016: Journal of the Royal Society, Interface
Dominic Bergeron, A-M S Tremblay
Analytic continuation of numerical data obtained in imaginary time or frequency has become an essential part of many branches of quantum computational physics. It is, however, an ill-conditioned procedure and thus a hard numerical problem. The maximum-entropy approach, based on Bayesian inference, is the most widely used method to tackle that problem. Although the approach is well established and among the most reliable and efficient ones, useful developments of the method and of its implementation are still possible...
August 2016: Physical Review. E
Fabrizio Camerin, Diego Frezzato
This study focuses on fluctuating classical systems in contact with a thermal bath, and whose configurational energetics undergoes cyclic transformations due to interaction with external perturbing agents. Under the assumptions that the configurational dynamics is a stochastic Markov process in the overdamped regime and that the nonequilibrium configurational distribution remains close to the underlying equilibrium one, we derived an analytic approximation of the average dissipated energy per cycle in the asymptotic limit (i...
August 2016: Physical Review. E
Alan Paris, George Atia, Azadeh Vosoughi, Stephen A Berman
OBJECTIVE: A characteristic of neurological signal processing is high levels of noise from sub-cellular ion channels up to whole-brain processes. In this paper, we propose a new model of electroencephalogram (EEG) background periodograms, based on a family of functions which we call generalized van der Ziel- McWhorter (GVZM) power spectral densities (PSDs). To the best of our knowledge, the GVZM PSD function is the only EEG noise model which has relatively few parameters, matches recorded EEG PSD's with high accuracy from 0 Hz to over 30 Hz, and has approximately 1=f behavior in the mid-frequencies without infinities...
September 7, 2016: IEEE Transactions on Bio-medical Engineering
Evie van der Spoel, Steffy W Jansen, Abimbola A Akintola, Bart E Ballieux, Christa M Cobbaert, P Eline Slagboom, Gerard Jan Blauw, Rudi G J Westendorp, Hanno Pijl, Ferdinand Roelfsema, Diana van Heemst
Reduced growth hormone (GH) signaling has been consistently associated with increased health and lifespan in various mouse models. Here, we assessed GH secretion and its control in relation with human familial longevity. We frequently sampled blood over 24 h in 19 middle-aged offspring of long-living families from the Leiden Longevity Study together with 18 of their partners as controls. Circulating GH concentrations were measured every 10 min and insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP3) every 4 h...
September 7, 2016: Aging Cell
Yen-Ting Lin, Chia-Hua Kuo, Yi-Ching Chen
There is little knowledge regarding the force production capacities of tug-of-war athletes, who undergo years of high-load strength training on handgrip muscles. The purpose of this investigation was to determine the force-grading strategies of tug-of-war athletes by examining force fluctuation properties at high exertion levels. Sixteen tug-of-war athletes and sixteen sedentary non-athletes performed sinusoidal handgrip grip at 50%-100% of maximal effort at 0.5 Hz under visual guidance. Force outputs of the designate task were recorded with a strain gauge...
October 31, 2016: Chinese Journal of Physiology
Peter C Fino, Maury A Nussbaum, Per Gunnar Brolinson
Two experiments compared multiple methods of estimating postural stability entropy to address: 1) if postural complexity differences exist between concussed and healthy athletes immediately following return-to-play; 2) which methods best detect such differences; and 3) what is an appropriate interpretation of such differences. First, center of pressure (COP) data were collected from six concussed athletes over the six weeks immediately following their concussion and from 24 healthy athletes. Second, 25 healthy non-athletes performed four quiet standing tasks: normal, co-contracting their lower extremity muscles, performing a cognitive arithmetic task, and voluntarily manipulating their sway...
August 26, 2016: Gait & Posture
Isaac C Sanchez, Sean P O'Keefe
Using a chemical potential route, the square-well (SW) fluid model is solved in a quasichemical approximation (QCSW). At low temperatures, the liquid reaches a limiting density greater than the triple point density of a SW fluid but less than the equilibrium liquid-to-solid transition density for hard spheres. As this unique density is approached with decreasing temperature, the liquid entropy also approaches an asymptotic value, thus averting the "entropy catastrophe". Mean-field models in the van der Waals (VDW) genre fail to predict this type of behavior...
September 8, 2016: Journal of Physical Chemistry. B
A R Hassan, R Maritz
In this paper, the analysis of a reactive hydromagnetic Poiseuille fluid flow under different chemical kinetics through a channel in the presence of a heat source is carried out. An exothermic reaction is assumed while the concentration of the material is neglected. The Adomian decomposition method together with Pade approximation technique are used to obtain the solutions of the governing nonlinear non-dimensional differential equations. Effects of various physical parameters on the velocity and temperature fields of the fluid flow are investigated...
2016: SpringerPlus
Nanmu Huang, Yu Zhang, William Calawerts, Jack J Jiang
OBJECTIVE: The present study aims to compare the correlation dimension and second-order entropy at the minimum embedding dimension with the correlation dimension (D2) and second-order entropy (K2) based on their efficiency and accuracy in differentiating between normal and pathologic voices. METHODS: The minimum embedding dimension was estimated with the Cao method. Nonlinear dynamic parameters, such as correlation dimension and second-order entropy, were used to quantitatively analyze the normal and pathologic voice samples...
August 20, 2016: Journal of Voice: Official Journal of the Voice Foundation
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