Naoki Furutani, Tetsuya Takahashi, Nobushige Naito, Takafumi Maruishi, Yuko Yoshimura, Chiaki Hasegawa, Tetsu Hirosawa, Mitsuru Kikuchi
Recently, measuring the complexity of body movements during sleep has been proven as an objective biomarker of various psychiatric disorders. Although sleep problems are common in children with autism spectrum disorder (ASD) and might exacerbate ASD symptoms, their objectivity as a biomarker remains to be established. Therefore, details of body movement complexity during sleep as estimated by actigraphy were investigated in typically developing (TD) children and in children with ASD. Several complexity analyses were applied to raw and thresholded data of actigraphy from 17 TD children and 17 children with ASD...
March 31, 2021: Entropy
Miguel Abadi, Vitor Amorim, Sandro Gallo
From a physical/dynamical system perspective, the potential well represents the proportional mass of points that escape the neighbourhood of a given point. In the last 20 years, several works have shown the importance of this quantity to obtain precise approximations for several recurrence time distributions in mixing stochastic processes and dynamical systems. Besides providing a review of the different scaling factors used in the literature in recurrence times, the present work contributes two new results: (1) For ϕ-mixing and ψ-mixing processes, we give a new exponential approximation for hitting and return times using the potential well as the scaling parameter...
March 23, 2021: Entropy
Marco Gherardi
Linear separability, a core concept in supervised machine learning, refers to whether the labels of a data set can be captured by the simplest possible machine: a linear classifier. In order to quantify linear separability beyond this single bit of information, one needs models of data structure parameterized by interpretable quantities, and tractable analytically. Here, I address one class of models with these properties, and show how a combinatorial method allows for the computation, in a mean field approximation, of two useful descriptors of linear separability, one of which is closely related to the popular concept of storage capacity...
March 4, 2021: Entropy
Zaijun Zhang, Daoyun Xu, Jincheng Zhou
The satisfiability (SAT) problem is a core problem in computer science. Existing studies have shown that most industrial SAT instances can be effectively solved by modern SAT solvers while random SAT instances cannot. It is believed that the structural characteristics of different SAT formula classes are the reasons behind this difference. In this paper, we study the structural properties of propositional formulas in conjunctive normal form (CNF) by the principle of structural entropy of formulas. First, we used structural entropy to measure the complex structure of a formula and found that the difficulty solving the formula is related to the structural entropy of the formula...
March 4, 2021: Entropy
Mahajabin Rahman, Benjamin M G D Carter, Shibu Saw, Ian M Douglass, Lorenzo Costigliola, Trond S Ingebrigtsen, Thomas B Schrøder, Ulf R Pedersen, Jeppe C Dyre
In the condensed liquid phase, both single- and multicomponent Lennard-Jones (LJ) systems obey the "hidden-scale-invariance" symmetry to a good approximation. Defining an isomorph as a line of constant excess entropy in the thermodynamic phase diagram, the consequent approximate isomorph invariance of structure and dynamics in appropriate units is well documented. However, although all measures of the structure are predicted to be isomorph invariant, with few exceptions only the radial distribution function (RDF) has been investigated...
March 20, 2021: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Tomasz Banaszkiewicz
Liquefied Natural Gas (LNG) must be vaporized before it is used in the combustion process. In most regasification terminals, energy that was previously expended to liquefy natural gas is dissipated in the environment. The paper proposes the use of the thermal effect of LNG regasification for the atmospheric air separation as a possible solution to the LNG exergy recovery problem. The presented idea is based on the coupling of the LNG regasification unit with an oxygen generator based on the Temperature Swing Adsorption (TSA) process...
March 15, 2021: Entropy
Qijun Tong, Kei Kobayashi
The distance and divergence of the probability measures play a central role in statistics, machine learning, and many other related fields. The Wasserstein distance has received much attention in recent years because of its distinctions from other distances or divergences. Although computing the Wasserstein distance is costly, entropy-regularized optimal transport was proposed to computationally efficiently approximate the Wasserstein distance. The purpose of this study is to understand the theoretical aspect of entropy-regularized optimal transport...
March 3, 2021: Entropy
Gianluca D'Addese, Laura Sani, Luca La Rocca, Roberto Serra, Marco Villani
The identification of emergent structures in complex dynamical systems is a formidable challenge. We propose a computationally efficient methodology to address such a challenge, based on modeling the state of the system as a set of random variables. Specifically, we present a sieving algorithm to navigate the huge space of all subsets of variables and compare them in terms of a simple index that can be computed without resorting to simulations. We obtain such a simple index by studying the asymptotic distribution of an information-theoretic measure of coordination among variables, when there is no coordination at all, which allows us to fairly compare subsets of variables having different cardinalities...
March 27, 2021: Entropy
Imon Banerjee, Vinayak A Rao, Harsha Honnappa
Datasets displaying temporal dependencies abound in science and engineering applications, with Markov models representing a simplified and popular view of the temporal dependence structure. In this paper, we consider Bayesian settings that place prior distributions over the parameters of the transition kernel of a Markov model, and seek to characterize the resulting, typically intractable, posterior distributions. We present a Probably Approximately Correct (PAC)-Bayesian analysis of variational Bayes (VB) approximations to tempered Bayesian posterior distributions, bounding the model risk of the VB approximations...
March 6, 2021: Entropy
Ilze A Auzina, Jakub M Tomczak
Many real-life processes are black-box problems, i.e., the internal workings are inaccessible or a closed-form mathematical expression of the likelihood function cannot be defined. For continuous random variables, likelihood-free inference problems can be solved via Approximate Bayesian Computation (ABC). However, an optimal alternative for discrete random variables is yet to be formulated. Here, we aim to fill this research gap. We propose an adjusted population-based MCMC ABC method by re-defining the standard ABC parameters to discrete ones and by introducing a novel Markov kernel that is inspired by differential evolution...
March 6, 2021: Entropy
Alianna J Maren
One of the biggest challenges in characterizing 2-D image topographies is finding a low-dimensional parameter set that can succinctly describe, not so much image patterns themselves, but the nature of these patterns. The 2-D cluster variation method (CVM), introduced by Kikuchi in 1951, can characterize very local image pattern distributions using configuration variables, identifying nearest-neighbor, next-nearest-neighbor, and triplet configurations. Using the 2-D CVM, we can characterize 2-D topographies using just two parameters; the activation enthalpy (ε0) and the interaction enthalpy (ε1)...
March 8, 2021: Entropy
Hafizur Rahman, Iraklis I Pipinos, Jason M Johanning, Sara A Myers
BACKGROUND: Patients with peripheral artery disease with intermittent claudication (PAD-IC) have altered gait variability from the first step they take, well before the onset of claudication pain. The mechanisms underlying these gait alterations are poorly understood. AIMS: To determine the effect of reduced blood flow on gait variability by comparing healthy older controls and patients with PAD-IC. We also determined the diagnostic value of gait variability parameters to identify the presence of PAD...
2021: PloS One
Sakthi Kumar Arul Prakash, Conrad Tucker
This work investigates the ability to classify misinformation in online social media networks in a manner that avoids the need for ground truth labels. Rather than approach the classification problem as a task for humans or machine learning algorithms, this work leverages user-user and user-media (i.e.,media likes) interactions to infer the type of information (fake vs. authentic) being spread, without needing to know the actual details of the information itself. To study the inception and evolution of user-user and user-media interactions over time, we create an experimental platform that mimics the functionality of real-world social media networks...
March 25, 2021: Scientific Reports
Khawla Ben Jeddou, Fatma Bouaziz, Fadia Ben Taheur, Oumèma Nouri-Ellouz, Raoudha Ellouz-Ghorbel, Semia Ellouz-Chaabouni
Adsorption of direct red 80 (DR 80) and methylene blue (MB) from aqueous solutions on potato peels (PP) has been compared. The use of peels in decontamination technology is very promising given the near zero-cost for the synthesis of those adsorbents. The selected potato peels were first analyzed by scanning using electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR). Then the adsorption behavior was studied in a batch system. The adsorption process is affected by various parameters such as the solution pH (2-11), the initial concentration of the dye (20, 50, 100, 150 and 200 mg L-1 ), the adsorbent dose (0...
March 2021: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Francesca Alù, Alessandro Orticoni, Elda Judica, Maria Cotelli, Paolo Maria Rossini, Francesca Miraglia, Fabrizio Vecchio
Aging is a multifactorial physiological process characterized by the accumulation of degenerative processes impacting on different brain functions, including the cognitive one. A tool largely employed in the investigation of brain networks is the electroencephalogram (EEG). Given the cerebral complexity and dynamism, many non-linear approaches have been applied to explore age-related brain electrical activity modulation detected by the EEG: one of them is the entropy, which measures the disorder of a system...
March 22, 2021: Mechanisms of Ageing and Development
Lucian Chan, Garrett M Morris, Geoffrey R Hutchison
The calculation of the entropy of flexible molecules can be challenging, since the number of possible conformers can grow exponentially with molecule size and many low-energy conformers may be thermally accessible. Different methods have been proposed to approximate the contribution of conformational entropy to the molecular standard entropy, including performing thermochemistry calculations with all possible stable conformations and developing empirical corrections from experimental data. We have performed conformer sampling on over 120,000 small molecules generating some 12 million conformers, to develop models to predict conformational entropy across a wide range of molecules...
March 24, 2021: Journal of Chemical Theory and Computation
Genchang Peng, Mehrdad Nourani, Jay Harvey, Hina Dave
Approximately, one third of patients with epilepsy are refractory to medical therapy and thus can be at high risk of injuries and sudden unexpected death. A low-complexity electroencephalography (EEG)-based seizure monitoring algorithm is critically important for daily use, especially for wearable monitoring platforms. This paper presents a personalized EEG feature selection approach, which is the key to achieve a reliable seizure monitoring with a low computational cost. We advocate a two-step, personalized feature selection strategy to enhance monitoring performances for each patient...
March 22, 2021: International Journal of Neural Systems
Abigail J Ameri, Zachary A Lewis
Neurospora crassa has been an important model organism for molecular biology and genetics for over 60 years. N. crassa has a complex life cycle, with over 28 distinct cell types and is capable of transcriptional responses to many environmental conditions including nutrient availability, temperature, and light. To quantify variation in N. crassa gene expression, we analyzed public expression data from 97 conditions and calculated the Shannon Entropy value for Neurospora's approximately 11,000 genes. Entropy values can be used to estimate the variability in expression for a single gene over a range of conditions and be used to classify individual genes as constitutive or condition-specific...
March 5, 2021: G3: Genes—Genomes—Genetics
Priyajit Mondal, T R Mahapatra, Rujda Parveen
This work is concerned with the numerical study of laminar, steady MHD mixed convection flow, and entropy generation analysis of <mml:math xmlns:mml=""> <mml:mi>A</mml:mi> <mml:msub> <mml:mrow> <mml:mi>l</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> <mml:msub> <mml:mrow> <mml:mi>O</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msub> </mml:math> -water nanofluid flowing in a lid-driven trapezoidal enclosure...
March 2021: Heliyon
Konstantinos Sakellariou, Thomas Stemler, Michael Small
We propose a computationally simple and efficient network-based method for approximating topological entropy of low-dimensional chaotic systems. This approach relies on the notion of an ordinal partition. The proposed methodology is compared to the three existing techniques based on counting ordinal patterns-all of which derive from collecting statistics about the symbolic itinerary-namely (i) the gradient of the logarithm of the number of observed patterns as a function of the pattern length, (ii) direct application of the definition of topological permutation entropy, and (iii) the outgrowth ratio of patterns of increasing length...
February 2021: Physical Review. E
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