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https://www.readbyqxmd.com/read/28335461/design-and-validation-of-a-low-cost-portable-device-to-quantify-postural-stability
#1
Yong Zhu
Measurement of the displacement of the center-of-pressure (COP) is an important tool used in biomechanics to assess postural stability and human balance. The goal of this research was to design and validate a low-cost portable device that can offer a quick indication of the state of postural stability and human balance related conditions. Approximate entropy (ApEn) values reflecting the amount of irregularity hiding in COP oscillations were used to calculate the index. The prototype adopted a portable design using the measurements of the load cells located at the four corners of a low-cost force platform...
March 18, 2017: Sensors
https://www.readbyqxmd.com/read/28330366/phase-behaviour-of-quasicrystal-forming-systems-of-core-corona-particles
#2
Harini Pattabhiraman, Marjolein Dijkstra
Using Monte Carlo simulations and free-energy calculations, we study the phase behaviour of a two-dimensional system of particles interacting with a hard core of diameter σHD and a repulsive square shoulder potential. The interest in this system lies in the formation of quasicrystals of different symmetries at specific square-shoulder widths δ as previously reported by Dotera et al. [Nature 506, 208 (2014)]. However, an insight into other possible periodic phases formed in these systems and the thermodynamic stability of both the periodic and quasicrystal phases is yet to be addressed...
March 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28316861/complexity-analysis-of-electroencephalogram-dynamics-in-patients-with-parkinson-s-disease
#3
Guotao Liu, Yanping Zhang, Zhenghui Hu, Xiuquan Du, Wanqing Wu, Chenchu Xu, Xiangyang Wang, Shuo Li
In this study, a new combination scheme has been proposed for detecting Parkinson's disease (PD) from electroencephalogram (EEG) signal recorded from normal subjects and PD patients. The scheme is based on discrete wavelet transform (DWT), sample entropy (SampEn), and the three-way decision model in analysis of EEG signal. The EEG signal is noisy and nonstationary, and, as a consequence, it becomes difficult to distinguish it visually. However, the scheme is a well-established methodology in analysis of EEG signal in three stages...
2017: Parkinson's Disease
https://www.readbyqxmd.com/read/28297917/free-energy-of-singular-sticky-sphere-clusters
#4
Yoav Kallus, Miranda Holmes-Cerfon
Networks of particles connected by springs model many condensed-matter systems, from colloids interacting with a short-range potential and complex fluids near jamming, to self-assembled lattices and various metamaterials. Under small thermal fluctuations the vibrational entropy of a ground state is given by the harmonic approximation if it has no zero-frequency vibrational modes, yet such singular modes are at the epicenter of many interesting behaviors in the systems above. We consider a system of N spherical particles, and directly account for the singularities that arise in the sticky limit where the pairwise interaction is strong and short ranged...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28285644/effects-of-transdermal-testosterone-gel-or-an-aromatase-inhibitor-on-serum-concentration-and-pulsatility-of-growth-hormone-in-older-men-with-age-related-low-testosterone
#5
Jenny Pena Dias, Johannes D Veldhuis, Olga Carlson, Michelle Shardell, Chee W Chia, Denise Melvin, Josephine M Egan, Shehzad Basaria
Growth hormone is the major regulator of growth and body composition. Pulsatile GH secretion declines exponentially with age. Testosterone replacement is being increasingly offered to older men with age-related low testosterone. Testosterone administration has been shown to stimulate GH secretion. However, little is known about the effect of testosterone aromatization to estradiol on GH pulsatility and its impact on IGF-1 in older men. OBJECTIVE: This randomized controlled proof-of-concept trial investigated the relative effects of testosterone and estradiol on GH pulsatility and IGF-1 in older men with low testosterone...
April 2017: Metabolism: Clinical and Experimental
https://www.readbyqxmd.com/read/28275778/a-thermodynamical-and-structural-study-on-the-complexation-of-trivalent-lanthanides-with-a-polycarboxylate-based-concrete-superplasticizer
#6
Daniel R Fröhlich, Martin M Maiwald, Franziska Taube, Johann Plank, Petra J Panak
The complexation of trivalent lanthanides with a commercial polycarboxylate based concrete superplasticizer (Glenium® 51) is investigated using different spectroscopic techniques. Time-resolved laser fluorescence spectroscopy (TRLFS) in combination with a charge neutralization model is used to determine temperature dependent conditional stability constants (log β'(T)) for the complexation of Eu(iii) with Glenium® 51 in 0.1 mol kg(-1) NaCl solution in the temperature range of 20-90 °C. Only one complex species is observed, and log β'(T) (given in kg per mol eq) shows a very slight increase with temperature from 7...
March 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28269675/effect-of-embedding-dimension-on-complexity-measures-in-identifying-arrhythmia
#7
Radhagayathri K Udhayakumar, Chandan Karmakar, Peng Li, Marimuthu Palaniswami
Entropy measures like Approximate entropy (ApEn) and Sample entropy (SampEn) are well established tools to analyze Heart Rate Variability (HRV) data. Critical parameters involved in these computations namely embedding dimension m and tolerance r are in most cases assumed to be 2 and 0.2*signal SD (standard devaition) respectively. Such assumptions do not work fairly across data sets and thus create misleading results in many cases. Problems with r have been addressed with the advent of newer entropy measures like Permutation entropy (PE), Fuzzy entropy (FuzzyEn) and Distribution entropy (DistEn) that simply eliminate, modify or replace r from calculations...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268915/clinical-viability-of-carotid-plaque-strain-estimation-using-b-mode-ultrasound-image-sequences
#8
Amir A Khan, Joseph C Hecker, Brajesh K Lal, Siddhartha Sikdar
It is estimated that approximately 30% of ischemic strokes are caused by rupture of plaque in the carotid artery. Development of techniques focusing on identifying plaques that are vulnerable to rupture is thus indispensable for stroke prevention. Recent studies have demonstrated that motion analysis of plaques from B-mode and RF ultrasound (US) image sequences can be used to estimate plaque strain. However, viability of these methods in a clinical setting, with variable acquisition protocols, has not been demonstrated yet...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28257094/online-detection-of-driver-fatigue-using-steering-wheel-angles-for-real-driving-conditions
#9
Zuojin Li, Shengbo Eben Li, Renjie Li, Bo Cheng, Jinliang Shi
This paper presents a drowsiness on-line detection system for monitoring driver fatigue level under real driving conditions, based on the data of steering wheel angles (SWA) collected from sensors mounted on the steering lever. The proposed system firstly extracts approximate entropy (ApEn)featuresfromfixedslidingwindowsonreal-timesteeringwheelanglestimeseries. Afterthat, this system linearizes the ApEn features series through an adaptive piecewise linear fitting using a given deviation. Then, the detection system calculates the warping distance between the linear features series of the sample data...
March 2, 2017: Sensors
https://www.readbyqxmd.com/read/28255330/comparison-of-different-features-and-classifiers-for-driver-fatigue-detection-based-on-a-single-eeg-channel
#10
Jianfeng Hu
Driver fatigue has become an important factor to traffic accidents worldwide, and effective detection of driver fatigue has major significance for public health. The purpose method employs entropy measures for feature extraction from a single electroencephalogram (EEG) channel. Four types of entropies measures, sample entropy (SE), fuzzy entropy (FE), approximate entropy (AE), and spectral entropy (PE), were deployed for the analysis of original EEG signal and compared by ten state-of-the-art classifiers. Results indicate that optimal performance of single channel is achieved using a combination of channel CP4, feature FE, and classifier Random Forest (RF)...
2017: Computational and Mathematical Methods in Medicine
https://www.readbyqxmd.com/read/28251959/effects-of-electron-doping-on-the-stability-of-the-metal-hydride-nah
#11
M A Olea-Amezcua, J F Rivas-Silva, O de la Peña-Seaman, R Heid, K P Bohnen
Alkali and alkali-earth metal hydrides have high volumetric and gravimetric hydrogen densities, but due to their high thermodynamic stability, they possess high dehydrogenation temperatures which may be reduced by transforming these compounds into less stable states/configurations. We present a systematic computational study of the electron doping effects on the stability of the alkali metal hydride NaH substituted with Mg, using the self-consistent version of the virtual crystal approximation to model the alloy Na1-x Mg x H...
March 2, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28245118/comparison-of-implicit-and-explicit-solvent-models-for-the-calculation-of-solvation-free-energy-in-organic-solvents
#12
Jin Zhang, Haiyang Zhang, Tao Wu, Qi Wang, David van der Spoel
Quantitative prediction of physical properties of liquids is important for many applications. Computational methods based on either explicit or implicit solvent models can be used to approximate thermodynamics properties of liquids. Here, we evaluate the predictive power of implicit solvent models for solvation free energy of organic molecules in organic solvents. We compared the results calculated with four generalized Born (GB) models (GB(Still), GB(HCT), GB(OBC)I, and GB(OBC)II), the Poisson-Boltzmann (PB) model, and the density-based solvent model SMD with previous solvation free energy calculations (Zhang et al...
March 14, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28241380/causality-transfer-entropy-and-allosteric-communication-landscapes-in-proteins-with-harmonic-interactions
#13
Aysima Hacisuleyman, Burak Erman
A fast and approximate method of generating allosteric communication landscapes in proteins is presented by using Schreiber's entropy transfer concept in combination with the Gaussian Network Model of proteins. Predictions of the model and the allosteric communication landscapes generated show that information transfer in proteins does not necessarily take place along a single path, but an ensemble of pathways is possible. The model emphasizes that knowledge of entropy only is not sufficient for determining allosteric communication and additional information based on time delayed correlations should be introduced, which leads to the presence of causality in proteins...
February 27, 2017: Proteins
https://www.readbyqxmd.com/read/28239056/thermodynamic-analysis-of-the-transition-of-liquid-crystals-from-lamellar-to-vesicular-phase
#14
Yasutaka Enomoto, Yoko Imai, Kazuo Tajima
Here, we report the results of thermodynamic analyses on the lamellar-vesicular transition for a cationic amphiphilic species, namely 2-hydroxyethyl di(alkanol)oxyethyl methylammonium methylsulfate (DEAE). Previously, we have shown that spontaneous vesicle formation from a Lα-lamellar liquid crystal (LC) phase only occurs on the addition of a quantitative amount of additives to the DEAE LC at certain temperatures and that this change occurs without the input of any extra mechanical energy. These lamellar-vesicular transitions occur in two steps: the first step is the formation of an excited state, caused by the solubilization of organic substances in the bilayer structure...
February 24, 2017: Journal of Oleo Science
https://www.readbyqxmd.com/read/28227934/effect-of-embedding-dimension-on-complexity-measures-in-identifying-arrhythmia
#15
Radhagayathri K Udhayakumar, Chandan Karmakar, Peng Li, Marimuthu Palaniswami, Radhagayathri K Udhayakumar, Chandan Karmakar, Peng Li, Marimuthu Palaniswami, Marimuthu Palaniswami, Radhagayathri K U Udhayakumar, Peng Li, Chandan Karmakar
Entropy measures like Approximate entropy (ApEn) and Sample entropy (SampEn) are well established tools to analyze Heart Rate Variability (HRV) data. Critical parameters involved in these computations namely embedding dimension m and tolerance r are in most cases assumed to be 2 and 0.2*signal SD (standard devaition) respectively. Such assumptions do not work fairly across data sets and thus create misleading results in many cases. Problems with r have been addressed with the advent of newer entropy measures like Permutation entropy (PE), Fuzzy entropy (FuzzyEn) and Distribution entropy (DistEn) that simply eliminate, modify or replace r from calculations...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227119/clinical-viability-of-carotid-plaque-strain-estimation-using-b-mode-ultrasound-image-sequences
#16
Amir A Khan, Joseph C Hecker, Brajesh K Lal, Siddhartha Sikdar, Amir A Khan, Joseph C Hecker, Brajesh K Lal, Siddhartha Sikdar, Siddhartha Sikdar, Brajesh K Lal, Amir A Khan, Joseph C Hecker
It is estimated that approximately 30% of ischemic strokes are caused by rupture of plaque in the carotid artery. Development of techniques focusing on identifying plaques that are vulnerable to rupture is thus indispensable for stroke prevention. Recent studies have demonstrated that motion analysis of plaques from B-mode and RF ultrasound (US) image sequences can be used to estimate plaque strain. However, viability of these methods in a clinical setting, with variable acquisition protocols, has not been demonstrated yet...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28208419/einstein-podolsky-rosen-paradox-implies-a-minimum-achievable-temperature
#17
David M Rogers
This work examines the thermodynamic consequences of the repeated partial projection model for coupling a quantum system to an arbitrary series of environments under feedback control. This paper provides observational definitions of heat and work that can be realized in current laboratory setups. In contrast to other definitions, it uses only properties of the environment and the measurement outcomes, avoiding references to the "measurement" of the central system's state in any basis. These definitions are consistent with the usual laws of thermodynamics at all temperatures, while never requiring complete projective measurement of the entire system...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28208386/statistical-model-of-a-flexible-inextensible-polymer-chain-the-effect-of-kinetic-energy
#18
V M Pergamenshchik, A B Vozniak
Because of the holonomic constraints, the kinetic energy contribution in the partition function of an inextensible polymer chain is difficult to find, and it has been systematically ignored. We present the first thermodynamic calculation incorporating the kinetic energy of an inextensible polymer chain with the bending energy. To explore the effect of the translation-rotation degrees of freedom, we propose and solve a statistical model of a fully flexible chain of N+1 linked beads which, in the limit of smooth bending, is equivalent to the well-known wormlike chain model...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28201915/2d-lattice-model-of-a-lipid-bilayer-microscopic-derivation-and-thermodynamic-exploration
#19
Davit Hakobyan, Andreas Heuer
Based on all-atom Molecular Dynamics (MD) simulations of a lipid bilayer we present a systematic mapping on a 2D lattice model. Keeping the lipid type and the chain order parameter as key variables we derive a free energy functional, containing the enthalpic interaction of adjacent lipids as well as the tail entropy. The functional form of both functions is explicitly determined for saturated and polyunsaturated lipids. By studying the lattice model via Monte Carlo simulations it is possible to reproduce the temperature dependence of the distribution of order parameters of the pure lipids, including the prediction of the gel transition...
February 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28157576/alterations-in-over-ground-walking-patterns-in-obese-and-overweight-adults
#20
Hao Meng, Daniel P O'Connor, Beom-Chan Lee, Charles S Layne, Stacey L Gorniak
Obesity has been associated with negative effects on postural control, including falls. Previous studies revealed different outcomes regarding the effects of obesity on gait features, and the use of BMI may lead to bias in assessing the true effects of obesity on gait. To better understand the effects of obesity on gait, it is important to examine gait features and associated body composition measures. The purpose of this study was: (1) to assess gait features of normal weight, overweight and obese adults, and (2) to assess the relationship between body composition measures and gait features...
January 24, 2017: Gait & Posture
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