Read by QxMD icon Read

Approximate entropy

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
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
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
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
Xiaoni Wang, Binbin Liu, Lin Xie, Xiaolin Yu, Mengjun Li, Jianbao Zhang
BACKGROUND: Mental arithmetic has been verified inducing cerebral and cardiovascular responses. However, the mechanism and sequential responses are still ambiguous. This study aims to reveal the mechanism of cardiovascular and autonomic responses and the related scalp positions that regulate the autonomic nerves system (ANS) during MA task. METHODS: 34 healthy male subjects aged between 19 and 27 years old (mean age 23.6 ± 2.3 years) were recruited in. Electrocardiogram, impedance cardiography, beat-to-beat blood pressure and electroencephalography were measured simultaneously and continuously during the experiments...
December 28, 2016: Biomedical Engineering Online
Heather J Chalfin, James E Verdone, Emma E van der Toom, Stephanie Glavaris, Michael A Gorin, Kenneth J Pienta
INTRODUCTION: Circulating tumor cells (CTCs) have great potential as circulating biomarkers for solid malignancies. Currently available assays for CTC detection rely on epithelial markers with somewhat limited sensitivity and specificity. We found that the staining pattern of nucleolin, a common nucleolar protein in proliferative cells, separates CTCs from white blood cells (WBCs) in men with metastatic prostate cancer. PATIENTS AND METHODS: Whole peripheral blood from 3 men with metastatic prostate cancer was processed with the AccuCyte CTC system (RareCyte, Seattle, WA)...
January 4, 2017: Clinical Genitourinary Cancer
Shu-Han Yu, Cheng-Ya Huang
In a postural-suprapostural task, appropriate prioritization is necessary to achieve task goals and maintain postural stability. A "posture-first" principle is typically favored by elderly people in order to secure stance stability, but this comes at the cost of reduced suprapostural performance. Using a postural-suprapostural task with a motor suprapostural goal, this study investigated differences between young and older adults in dual-task cost across varying task prioritization paradigms. Eighteen healthy young (mean age: 24...
2017: PloS One
Frantisek Karlicky, Eva Otyepkova, Rabindranath Lo, Michal Pitonak, Petr Jurecka, Martin Pykal, Pavel Hobza, Michal Otyepka
Understanding strength and nature of noncovalent binding to surfaces imposes significant challenge both for computations and experiments. We explored the adsorption of five small nonpolar organic molecules (acetone, acetonitrile, dichloromethane, ethanol, ethyl acetate) to fluorographene and fluorographite using inverse gas chromatography and theoretical calculations, providing new insights into the strength and nature of adsorption of small organic molecules on these surfaces. The measured adsorption enthalpies on fluorographite range from -7 to -13 kcal/mol and are by 1-2 kcal/mol lower than those measured on graphene/graphite, which indicates higher affinity of organic adsorbates to flu-rographene than to graphene...
February 1, 2017: Journal of Chemical Theory and Computation
G D Brand, D A T Pires, J R Furtado, A Cooper, S M Freitas, C Bloch
The black-eyed pea trypsin/chymotrypsin inhibitor (BTCI) forms concentration dependent homomultimers, as previously demonstrated by Light scattering and Atomic Force Microscopy. Considering that these self-aggregates might influence their binding to cognate enzymes, we investigated the interaction of BTCI at picomolar concentrations using surface immobilized Chymotrypsin (α-CT) and Trypsin (T) by Surface Plasmon Resonance. Our results indicate that BTCI has subnanomolar affinity to both immobilized enzymes, which is approximately two orders of magnitude higher than previously reported...
January 26, 2017: Archives of Biochemistry and Biophysics
Yimin Jiang, Mario Liu
Two approaches exist to account for granular dynamics: The athermal one takes grains as elementary, the thermal one considers the total entropy that includes microscopic degrees of freedom such as phonons and electrons. Discrete element method (DEM), granular kinetic theory and athermal statistical mechanics (ASM) belong to the first, granular solid hydrodynamics (GSH) to the second one. A discussion of the conceptual differences between both is given here, leading, among others, to the following insights: 1) While DEM and granular kinetic theory are well justified to take grains as athermal, any entropic consideration is far less likely to succeed...
January 2017: European Physical Journal. E, Soft Matter
Alessia Longo, Ruud Meulenbroek
Movement variability of the upper limb was investigated using a bimanual Fitts' task. Participants tapped rhythmically between target-pairs of different Index of Difficulties (ID) for three intervals of 20 min each. We studied the effects of ID and time-on-task on movement time, end-point variability, approximate entropy and standard deviation of relative phase. Lower ID and time-on-task caused decreasing movement time and increasing end-point variability. Moreover, standard deviation of relative phase and approximate entropy moderately increased...
January 25, 2017: Motor Control
Maolin Chen, Siying Wang, Mingwei Wang, Youchuan Wan, Peipei He
Automatic registration of terrestrial laser scanning point clouds is a crucial but unresolved topic that is of great interest in many domains. This study combines terrestrial laser scanner with a smartphone for the coarse registration of leveled point clouds with small roll and pitch angles and height differences, which is a novel sensor combination mode for terrestrial laser scanning. The approximate distance between two neighboring scan positions is firstly calculated with smartphone GPS coordinates. Then, 2D distribution entropy is used to measure the distribution coherence between the two scans and search for the optimal initial transformation parameters...
January 20, 2017: Sensors
Christian Wachinger, Matthew Brennan, Greg Sharp, Polina Golland
OBJECTIVE: We introduce descriptor-based segmentation that extends existing patch-based methods by combining intensities, features and location information. Since it is unclear which image features are best suited for patch selection, we perform a broad empirical study on a multitude of different features. We extend non-local means segmentation by including image features and location information. We search larger windows with an efficient nearest neighbor search based on kd-trees. We compare a large number of image features...
September 16, 2016: IEEE Transactions on Bio-medical Engineering
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
Lihua Chen, Vyacheslav S Bryantsev
Accurate prediction of melting points of ILs is important both from the fundamental point of view and from the practical perspective for screening ILs with low melting points and broadening their utilization in a wider temperature range. In this work, we present an ab initio approach to calculate melting points of ILs with known crystal structures and illustrate its application for a series of 11 ILs containing imidazolium/pyrrolidinium cations and halide/polyatomic fluoro-containing anions. The melting point is determined as a temperature at which the Gibbs free energy of fusion is zero...
February 1, 2017: Physical Chemistry Chemical Physics: PCCP
Christian Donner, Klaus Obermayer, Hideaki Shimazaki
The models in statistical physics such as an Ising model offer a convenient way to characterize stationary activity of neural populations. Such stationary activity of neurons may be expected for recordings from in vitro slices or anesthetized animals. However, modeling activity of cortical circuitries of awake animals has been more challenging because both spike-rates and interactions can change according to sensory stimulation, behavior, or an internal state of the brain. Previous approaches modeling the dynamics of neural interactions suffer from computational cost; therefore, its application was limited to only a dozen neurons...
January 2017: PLoS Computational Biology
Denis S Grebenkov, Gleb Oshanin
We study the mean first exit time (Tε) of a particle diffusing in a circular or a spherical micro-domain with an impenetrable confining boundary containing a small escape window (EW) of an angular size ε. Focusing on the effects of an energy/entropy barrier at the EW, and of the long-range interactions (LRIs) with the boundary on the diffusive search for the EW, we develop a self-consistent approximation to derive for Tε a general expression, akin to the celebrated Collins-Kimball relation in chemical kinetics and accounting for both rate-controlling factors in an explicit way...
January 10, 2017: Physical Chemistry Chemical Physics: PCCP
Dylan Suvlu, Seneviratne Samaratunga, D Thirumalai, Jayendran C Rasaiah
Understanding structure formation in polypeptide chains and synthetic polymers encapsulated in pores is important in biology and nanotechnology. We present replica exchange molecular dynamics studies of the phase diagram for α-helix formation of capped polyalanine in nanotubes (NT) open to a water reservoir as a function of the NT diameter and hydrophobicity. A helix forms only in a narrow range of diameters, which surprisingly is comparable to the width of the ribosome tunnel. Increasing the hydrophobicity enhances helicity in the NT...
January 19, 2017: Journal of Physical Chemistry Letters
G Zhao, J L Yan, Y J Yu, M C Ding, X G Zhao, H Y Wang
The relationship between structural order and water-like anomalies in tetrahedral liquids is still open. Here, first-principle molecular dynamics are performed to study it in metastable liquid Si. It is found that in T-P phase diagram, there indeed exists a structural anomaly region, which encloses density anomaly but not diffusivity anomaly. This is consistent with that of SW Si and BKS SiO2 but different from that of SPC/E water. Two-body excess entropy anomaly can neither capture the diffusivity, structural, and density anomalies, as it can in a two-scale potential fluid...
January 5, 2017: Scientific Reports
Andreas Elmerdahl Olsen, Jeppe C Dyre, Thomas B Schrøder
Computer simulations show that liquids of molecules with harmonic intramolecular bonds may have "pseudoisomorphic" lines of approximately invariant dynamics in the thermodynamic phase diagram. We demonstrate that these lines can be identified by requiring scale invariance of the inherent-structure reduced-unit low-frequency vibrational spectrum evaluated for a single equilibrium configuration. This rationalizes why generalized excess-entropy scaling, density scaling, and isochronal superposition apply for many liquids with internal degrees of freedom...
December 28, 2016: Journal of Chemical Physics
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"