4,878 results match your criteria Algebraic And Geometric Topology[Journal]


Harmonic tropical morphisms and approximation.

Authors:
Lionel Lang

Math Ann 2020 4;377(1):379-419. Epub 2020 Mar 4.

Department of Mathematics, Stockholm University, 106 91 Stockholm, Sweden.

are generalisations of amoebas of algebraic curves immersed in complex tori. Introduced by Krichever in 2014, the consideration of such objects suggests to enlarge the scope of tropical geometry. In the present paper, we introduce the notion of harmonic morphisms from tropical curves to affine spaces and show how these morphisms can be systematically described as limits of families of harmonic amoeba maps on Riemann surfaces. Read More

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http://dx.doi.org/10.1007/s00208-020-01971-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7319353PMC

Pole assignment stabilization for a class of switched nonlinear time-varying delay systems.

ISA Trans 2020 Jun 30. Epub 2020 Jun 30.

Laboratory of Automation, Electrical Systems and Environment (LAESE), National Engineering School of Monastir (ENIM), Ibn El Jazzar, Skaness, 5019, Monastir, University of Monastir, Tunisia. Electronic address:

This paper investigates the pole assignment stabilization with memory state feedback controllers for switched nonlinear time-varying delay systems. More general time-varying delays which depend on the subsystem number are considered. Based on novel common Lyapunov functions (CLFs), the aggregation techniques, the proprieties and the Borne-Gentina criterion, new algebraic stabilization criteria are established. Read More

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http://dx.doi.org/10.1016/j.isatra.2020.06.022DOI Listing

Automatic identification of myopia based on ocular appearance images using deep learning.

Ann Transl Med 2020 Jun;8(11):705

State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.

Background: Myopia is the leading cause of visual impairment and affects millions of children worldwide. Timely and annual manual optometric screenings of the entire at-risk population improve outcomes, but screening is challenging due to the lack of availability and training of assessors and the economic burden imposed by the screenings. Recently, deep learning and computer vision have shown powerful potential for disease screening. Read More

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http://dx.doi.org/10.21037/atm.2019.12.39DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327333PMC

Eigenvectors of polarization coherency matrices.

J Opt Soc Am A Opt Image Sci Vis 2020 Jul;37(7):1143-1154

Calculation of the eigenvectors of two- and three-dimensional coherency matrices, and the four-dimensional coherency matrix associated with a Mueller matrix, is considered, especially for algebraic cases, in the light of recently published algorithms. The preferred approach is based on a combination of an evaluation of the characteristic polynomial and an adjugate matrix. The diagonal terms of the coherency matrix are given in terms of the characteristic polynomial of reduced matrices as functions of the eigenvalues of the coherency matrix. Read More

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http://dx.doi.org/10.1364/JOSAA.391902DOI Listing

Distributed Optimization Design for Computation of Algebraic Riccati Inequalities.

IEEE Trans Cybern 2020 Jul 1;PP. Epub 2020 Jul 1.

This article proposes a distributed optimization design to compute continuous-time algebraic Riccati inequalities (ARIs), where the information of matrices is distributed among agents. We propose a design procedure to tackle the nonlinearity, the inequality, and the coupled information structure of ARI; then, we design a distributed algorithm based on an optimization approach and analyze its convergence properties. The proposed algorithm is able to verify whether ARI is feasible in a distributed way and converges to a solution if ARI is feasible for any initial condition. Read More

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http://dx.doi.org/10.1109/TCYB.2020.3000791DOI Listing

The quaternion-based spatial-coordinate and orientation-frame alignment problems.

Authors:
Andrew J Hanson

Acta Crystallogr A Found Adv 2020 Jul 18;76(Pt 4):432-457. Epub 2020 Jun 18.

Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana, USA.

The general problem of finding a global rotation that transforms a given set of spatial coordinates and/or orientation frames (the `test' data) into the best possible alignment with a corresponding set (the `reference' data) is reviewed. For 3D point data, this `orthogonal Procrustes problem' is often phrased in terms of minimizing a root-mean-square deviation (RMSD) corresponding to a Euclidean distance measure relating the two sets of matched coordinates. This article focuses on quaternion eigensystem methods that have been exploited to solve this problem for at least five decades in several different bodies of scientific literature, where they were discovered independently. Read More

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http://dx.doi.org/10.1107/S2053273320002648DOI Listing

[Metrological assessment of the averaged phase cardiocycle in solving problems of rehabilitation and sports medicine].

Vopr Kurortol Fizioter Lech Fiz Kult 2020 ;97(3):14-23

Tavric academy, Crimea federal university named after V.I. Vernadsky, Simferopol, Republic of Crimea, Russia.

Electrocardiography is one of the leading and most common methods of instrumental research of heart biorhythms in primary medical and social care. The development of information and digital technologies, robotics for the purpose of preclinical assessment and ranking of myocardial status in different categories of the population for preventive purposes has allowed us to create highly sensitive methods for recording and processing biosignals. Converting and displaying a cardiosignal on the phase plane to obtain a averaged phase cardiocycle (APC) is a demostrative instrumental method of research. Read More

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http://dx.doi.org/10.17116/kurort20209703114DOI Listing
January 2020

Event-Triggered Output-Feedback Control for Large-Scale Systems With Unknown Hysteresis.

IEEE Trans Cybern 2020 Jun 25;PP. Epub 2020 Jun 25.

This article focuses on the event-triggered-based adaptive neural-network (NN) control problem for nonlinear large-scale systems (LSSs) in the presence of full-state constraints and unknown hysteresis. The characteristic of radial basis function NNs is utilized to construct a state observer and address the algebraic loop problem. To reduce the communication burden and the signal transmission frequency, the event-triggered mechanism and the encoding-decoding strategy are proposed with the help of a backstepping control technique. Read More

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http://dx.doi.org/10.1109/TCYB.2020.2997943DOI Listing

Relaxation Dynamics of the Triazene Compound Berenil in DNA-Minor-Groove Confinement After Photo-Excitation.

J Chem Theory Comput 2020 Jun 25. Epub 2020 Jun 25.

The effects of the biomolecular embedding on the photo-induced relaxation process of the DNA minor-groove binder berenil, diminazene aceturate, is studied with quantum mechanics/molecular mechanics, QM/MM, calculations that employ the algebraic diagrammatic construction through second-order, ADC(2), for the quantum mechanical and an atomistic polarizable embedding for the classical part. The lowest singlet excitation to the S state is a bright transition with a ππ character and a perichromatic red-shift, due to the interactions with the solvent and DNA. The excited-state relaxation pathway is a two-step mechanism, an N=N azo-bond stretch followed by a volume-conserving bicycle-pedal twist. Read More

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http://dx.doi.org/10.1021/acs.jctc.0c00489DOI Listing

Many-body localization in a long-range model: Real-space renormalization-group study.

Phys Rev E 2020 May;101(5-1):052108

SISSA, via Bonomea 265, 34136 Trieste, Italy.

We develop a real-space renormalization-group (RSRG) scheme by appropriately inserting the long-range hopping t∼r^{-α} with nearest-neighbor interaction to study the entanglement entropy and maximum block size for the many-body localization (MBL) transition. We show that for α<2 there exists a localization transition with renormalized disorder that depends logarithmically on the finite size of the system. The transition observed for α>2 does not need a rescaling in disorder strength. Read More

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http://dx.doi.org/10.1103/PhysRevE.101.052108DOI Listing

Scale invariance of the homentropic inviscid Euler equations with application to the Noh problem.

Phys Rev E 2020 May;101(5-1):053101

Applied Physics, Los Alamos National Laboratory, P.O. Box 1663, MS T082, Los Alamos, New Mexico 87545, USA.

We investigate the inviscid compressible flow (Euler) equations constrained by an "isentropic" equation of state (EOS), whose functional form in pressure is an arbitrary function of density alone. Under the aforementioned condition, we interrogate using symmetry methods the scale-invariance of the homentropic inviscid Euler equations. We find that under general conditions, we can reduce the inviscid Euler equations into a system of two coupled ordinary differential equations. Read More

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http://dx.doi.org/10.1103/PhysRevE.101.053101DOI Listing

A new Lyapunov functional for stability analysis of neutral-type Hopfield neural networks with multiple delays.

Authors:
Ozlem Faydasicok

Neural Netw 2020 Jun 16;129:288-297. Epub 2020 Jun 16.

Department of Mathematics, Faculty of Science, Istanbul University, Vezneciler, Istanbul, Turkey. Electronic address:

This research paper conducts an investigation into the stability issue for a more general class of neutral-type Hopfield neural networks that involves multiple time delays in the states of neurons and multiple neutral delays in the time derivatives of the states of neurons. By constructing a new proper Lyapunov functional, an alternative easily verifiable algebraic criterion for global asymptotic stability of this type of Hopfield neural systems is derived. This new stability condition is entirely independent of time and neutral delays. Read More

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http://dx.doi.org/10.1016/j.neunet.2020.06.013DOI Listing

Formal Modelling of FHIR Based, Medical Data Exchange Using Algebraic Petri Nets.

Stud Health Technol Inform 2020 Jun;270:597-601

Institute for Medical Informatics and Biometry, Carl Gustav Carus Faculty of Medicine, Technische Universität Dresden.

Enabling interoperability is a challenging task in medical data exchange and is often addressed by the use of versatile communication standards like HL7 FHIR. Although daily routine and scientific experiences show its suitability, the use comes with major risks regarding safety and security of data. To overcome these problems, we present an approach to enable a formal verification of medical communication use cases. Read More

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http://dx.doi.org/10.3233/SHTI200230DOI Listing

Measurement of Chladni Mode Shapes with an Optical Lever Method.

J Vis Exp 2020 Jun 5(160). Epub 2020 Jun 5.

School of Mathematics and Physics, University of Science and Technology Beijing;

Quantitatively determining the Chladni pattern of an elastic plate is of great interest in both physical science and engineering applications. In this paper, a method of measuring mode shapes of a vibrating plate based on an optical lever method is proposed. Three circular acrylic plates were employed in the measurement under different center harmonic excitations. Read More

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http://dx.doi.org/10.3791/61020DOI Listing

On relaxation systems and their relation to discrete velocity Boltzmann models for scalar advection-diffusion equations.

Philos Trans A Math Phys Eng Sci 2020 Jul 22;378(2175):20190400. Epub 2020 Jun 22.

Lattice Boltzmann Research Group, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.

The connection of relaxation systems and discrete velocity models is essential to the progress of stability as well as convergence results for lattice Boltzmann methods. In the present study we propose a formal perturbation ansatz starting from a scalar one-dimensional target equation, which yields a relaxation system specifically constructed for its equivalence to a discrete velocity Boltzmann model as commonly found in lattice Boltzmann methods. Further, the investigation of stability structures for the discrete velocity Boltzmann equation allows for algebraic characterizations of the equilibrium and collision operator. Read More

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http://dx.doi.org/10.1098/rsta.2019.0400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7333944PMC

Superiorized method for metal artifact reduction.

Med Phys 2020 Jun 16. Epub 2020 Jun 16.

School of STEM, University of Washington Bothell, Box 358538, 18115 Campus Way NE, Bothell, WA, 98011, USA.

Purpose: Metal artifact reduction (MAR) is a challenging problem in computed tomography (CT) imaging. A popular class of MAR methods replace sinogram measurements that are corrupted by metal with artificial data, typically generated from some combination of interpolation along with other heuristics. While these "projection completion" approaches are successful in eliminating severe artifacts, secondary artifacts may be introduced by the artificial data. Read More

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http://dx.doi.org/10.1002/mp.14332DOI Listing

Two-Loop Four-Graviton Scattering Amplitudes.

Phys Rev Lett 2020 May;124(21):211601

Max Planck Insitute for Physics (Werner Heisenberg Institute), D-80805 Munich, Germany.

We present the analytic form of the two-loop four-graviton scattering amplitudes in Einstein gravity. To remove ultraviolet divergences we include counterterms quadratic and cubic in the Riemann curvature tensor. The two-loop numerical unitarity approach is used to deal with the challenging momentum dependence of the interactions. Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.211601DOI Listing

Crosstalk dynamics between the circadian clock and the mTORC1 pathway.

J Theor Biol 2020 Jun 7;501:110360. Epub 2020 Jun 7.

Unidad Monterrey, Centro de Investigación y de Estudios Avanzados del IPN, Apodaca, Nuevo León, Mexico.

Crosstalk between the circadian clock clockwork and cellular metabolic regulatory networks is crucial to ensure an adequate response of an organism to the day/night cycle. mTOR (mammalian/mechanistic target of rapamycin) is a master growth regulator and sensor of nutrient status, which is part of the mTOR complex 1 (mTORC1). While the circadian clock confers rhythmicity to the mTOR protein by regulating its degradation rate, mTORC1 activity diminishes period and augments amplitude of circadian oscillations at the cellular level by a currently unknown mechanism. Read More

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http://dx.doi.org/10.1016/j.jtbi.2020.110360DOI Listing

The Effects of Algebraic Equation Solving Intervention for Students With Mathematics Learning Difficulties.

J Learn Disabil 2020 Jun 8:22219420930814. Epub 2020 Jun 8.

University of Nebraska-Lincoln, USA.

The purpose of this study was to examine the effects of algebraic equation solving intervention for sixth graders with mathematics learning difficulties (MD). A total of 48 students with MD were randomly assigned to either the algebraic equation solving intervention, ( = 24) or control condition ( = 24). The multicomponent intervention was based on the principles of explicit instruction and focused on improving conceptual and procedural knowledge of algebraic equation solving using concrete manipulatives. Read More

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http://dx.doi.org/10.1177/0022219420930814DOI Listing

The Meshless Analysis of Scale-Dependent Problems for Coupled Fields.

Materials (Basel) 2020 Jun 2;13(11). Epub 2020 Jun 2.

School of Engineering and Materials Sciences, Queen Mary University of London, Mile End, London E14NS, UK.

The meshless local Petrov-Galerkin (MLPG) method was developed to analyze 2D problems for flexoelectricity and higher-grade thermoelectricity. Both problems were multiphysical and scale-dependent. The size effect was considered by the strain and electric field gradients in the flexoelectricity, and higher-grade heat flux in the thermoelectricity. Read More

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http://dx.doi.org/10.3390/ma13112527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7321424PMC

Anomalous transmission through periodic resistive sheets.

J Acoust Soc Am 2020 May;147(5):3124

Laboratoire d'Acoustique de l'Université du Mans, Unite Mixte de Recherche 6613, Centre National de la Recherche Scientifique, Avenue O. Messiaen, F-72085 LE MANS Cedex 9, France.

This work investigates anomalous transmission effects in periodic dissipative media, which is identified as an acoustic analogue of the Borrmann effect. For this, the scattering of acoustic waves on a set of equidistant resistive sheets is considered. It is shown both theoretically and experimentally that at the Bragg frequency of the system, the transmission coefficient is significantly higher than at other frequencies. Read More

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http://dx.doi.org/10.1121/10.0001166DOI Listing

Characterizing plasma with emission tomography-Feasibility study on synthetic and experimental data.

Rev Sci Instrum 2020 May;91(5):053102

Department of Physics, Center for Accelerator Science, Old Dominion University, Norfolk, Virginia 23529, USA.

We present a feasibility study on different tomographic algorithms to overcome the issues of finite sets of projection data, limited viewing angles, and noisy data, which cause the tomographic reconstruction to be an ill-posed inversion problem. We investigated three approaches: single angle Abel inversion, two angle approach, and multiple angle 2D plasma tomography. These methods were tested on symmetric and asymmetric sample functions and on experimental results from a supersonic flowing argon microwave plasma sustained in a cylindrical quartz cavity. Read More

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http://dx.doi.org/10.1063/1.5138921DOI Listing

Quasi-bipartite synchronization of signed delayed neural networks under impulsive effects.

Neural Netw 2020 May 19;129:31-42. Epub 2020 May 19.

School of Mathematics and Statistics, Shandong Normal University, Ji'nan 250014, China. Electronic address:

This paper mainly studies quasi-bipartite synchronization (QBPS) of signed delayed neural networks (SDNNs) under impulsive effects, in which the nodes have cooperative as well as antagonistic interactions. It is assumed that disturbance occurs in the communication channels between some neighboring agents at impulsive occurring instants. Under the balanced network topology, some sufficient criteria to achieve QBPS of SDNNs are proposed by utilizing algebraic graph theory and extended Halanay differential inequality. Read More

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http://dx.doi.org/10.1016/j.neunet.2020.05.012DOI Listing

A Geometric Measure Theory Approach to Identify Complex Structural Features on Soft Matter Surfaces.

J Chem Theory Comput 2020 Jun 17. Epub 2020 Jun 17.

Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.

The structural features that protrude above or below a soft matter interface are well-known to be related to interfacially mediated chemical reactivity and transport processes. It is a challenge to develop a robust algorithm for identifying these organized surface structures, as the morphology can be highly varied and they may exist on top of an interface containing significant interfacial roughness. A new algorithm that employs concepts from geometric measure theory, algebraic topology, and optimization is developed to identify candidate structures at a soft matter surface, and then, using a probabilistic approach, to rank their likelihood of being a complex structural feature. Read More

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http://dx.doi.org/10.1021/acs.jctc.0c00260DOI Listing

Mittag-Leffler Synchronization of Delayed Fractional Memristor Neural Networks via Adaptive Control.

IEEE Trans Neural Netw Learn Syst 2020 Jun 1;PP. Epub 2020 Jun 1.

This brief is devoted to exploring the global Mittag-Leffler (ML) synchronization problem of fractional-order memristor neural networks (FOMNNs) with leakage delay via a hybrid adaptive controller. By applying Fillipov's theory and the Lyapunov functional method, the novel algebraic sufficient condition for the global ML synchronization of FOMNNs is derived. Finally, a simulation example is presented to show the practicability of our findings. Read More

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http://dx.doi.org/10.1109/TNNLS.2020.2995718DOI Listing

Adaptive Dynamic Programming for Model-Free Global Stabilization of Control Constrained Continuous-Time Systems.

IEEE Trans Cybern 2020 May 28;PP. Epub 2020 May 28.

This article addresses the problem of global stabilization of continuous-time linear systems subject to control constraints using a model-free approach. We propose a gain-scheduled low-gain feedback scheme that prevents saturation from occurring and achieves global stabilization. The framework of parameterized algebraic Riccati equations (AREs) is employed to design the low-gain feedback control laws. Read More

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http://dx.doi.org/10.1109/TCYB.2020.2989419DOI Listing

Automated gleason grading on prostate biopsy slides by statistical representations of homology profile.

Comput Methods Programs Biomed 2020 May 26;194:105528. Epub 2020 May 26.

School of Automation, Nanjing University of Information Science & Technology, Nanjing 210044, China; Jiangsu Key Laboratory of Big Data Analysis Technique and CICAEET, Nanjing University of Information Science and Technology, Nanjing 210044, China. Electronic address:

Background And Objective: Gleason grading system is currently the clinical gold standard for determining prostate cancer aggressiveness. Prostate cancer is typically classified into one of 5 different categories with 1 representing the most indolent disease and 5 reflecting the most aggressive disease. Grades 3 and 4 are the most common and difficult patterns to be discriminated in clinical practice. Read More

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http://dx.doi.org/10.1016/j.cmpb.2020.105528DOI Listing

Comparison of Reaction Field Schemes for Coupling Continuum Solvation Models with Wave Function Methods for Excitation Energies.

J Chem Theory Comput 2020 Jun 15. Epub 2020 Jun 15.

Arbeitsgruppe Quantenchemie, Ruhr-Universität, Bochum 44780, Germany.

We address in this work the question to which extend reaction field schemes for correlated wave function methods give accurate excitation energies and, at the same time, physically consistent potential energy surfaces. The performance of the perturbation on energy (PTE), perturbation on energy and density (PTED), and post-SCF reaction field schemes is compared for the algebraic diagrammatic construction through second-order, ADC(2), as electronic structure and the conductor-like screening model COSMO as solvation model. The conditions on reaction field schemes to give physically consistent potential energies surfaces are discussed at the example of 4-(,-dimethylamino)benzonitrile, which is used as a test case to assess the artifacts introduced by state-specific contributions to the effective Hamiltonian. Read More

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http://dx.doi.org/10.1021/acs.jctc.0c00316DOI Listing

Absorption spectra of pyruvic acid in water: insights from calculations for small hydrates and comparison to experiment.

Phys Chem Chem Phys 2020 Jun 27;22(22):12658-12670. Epub 2020 May 27.

Institute of Chemistry, Fritz Haber Research Center, Hebrew University of Jerusalem, Jerusalem 91904, Israel.

Pyruvic acid is abundant in the atmosphere and in seawater, being a decay product of living organisms. Although very small in size (10 atoms), pyruvic acid exhibits conformational complexity in the gas phase and in solution, which is reflected in the UV spectrum. The gas phase UV spectrum of pyruvic acid differs from the spectrum of pyruvic acid in water. Read More

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http://dx.doi.org/10.1039/d0cp01810dDOI Listing

Real-time Inference and Detection of Disruptive EEG Networks for Epileptic Seizures.

Sci Rep 2020 May 26;10(1):8653. Epub 2020 May 26.

Department of Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, MO, 63130, USA.

Recent studies in brain science and neurological medicine paid a particular attention to develop machine learning-based techniques for the detection and prediction of epileptic seizures with electroencephalogram (EEG). As a noninvasive monitoring method to record brain electrical activities, EEG has been widely used for capturing the underlying dynamics of disruptive neuronal responses across the brain in real-time to provide clinical guidance in support of epileptic seizure treatments in practice. In this study, we introduce a novel dynamic learning method that first infers a time-varying network constituted by multivariate EEG signals, which represents the overall dynamics of the brain network, and subsequently quantifies its topological property using graph theory. Read More

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http://dx.doi.org/10.1038/s41598-020-65401-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7251100PMC

Reproducing absorption spectra of pH indicators from RGB values of microscopic images.

Talanta 2020 Aug 20;216:120952. Epub 2020 Mar 20.

Graduate School of Regional Development and Creativity, Utsunomiya University, Utsunomiya, Tochigi, 321-8585, Japan. Electronic address:

Absorption spectra of pH indicators in aqueous solutions were reproduced from RGB values of microscopic images utilizing principal component analysis (PCA) and linear algebraic treatments. The reproduction of absorption spectra comprises the following three steps: (1) determining the loading spectra by PCA, (2) determining the conversion matrix from the RGB values to the score vectors, and (3) reproducing the absorption spectra by linear combination of the loading spectra and the score vectors. The reproducibility of the absorption spectra was demonstrated by employing bromothymol blue and methyl red solutions as pH indicators. Read More

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http://dx.doi.org/10.1016/j.talanta.2020.120952DOI Listing

Quantitative Redox Biology of Exercise.

Int J Sports Med 2020 May 26. Epub 2020 May 26.

Centre for Atherothrombotic & Metabolic Disease, Hull York Medical School, Hull, United Kingdom of Great Britain and Northern Ireland.

Biology is rich in claims that reactive oxygen and nitrogen species are involved in every biological process and disease. However, many quantitative aspects of redox biology remain elusive. The important quantitative parameters you need to address the feasibility of redox reactions in vivo are: rate of formation and consumption of a reactive oxygen and nitrogen species, half-life, diffusibility and membrane permeability. Read More

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http://dx.doi.org/10.1055/a-1157-9043DOI Listing

Neural-Network-Based Adaptive Event-Triggered Consensus Control of Nonstrict-Feedback Nonlinear Systems.

IEEE Trans Neural Netw Learn Syst 2020 May 18;PP. Epub 2020 May 18.

The event-triggered consensus control problem is studied for nonstrict-feedback nonlinear systems with a dynamic leader. Neural networks (NNs) are utilized to approximate the unknown dynamics of each follower and its neighbors. A novel adaptive event-trigger condition is constructed, which depends on the relative output measurement, the NN weights estimations, and the states of each follower. Read More

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http://dx.doi.org/10.1109/TNNLS.2020.2991015DOI Listing
May 2020
4.370 Impact Factor

Global dynamics of healthy and cancer cells competing in the hematopoietic system.

Math Biosci 2020 May 19;326:108372. Epub 2020 May 19.

IMFUFA, Department of Science and Environment, Roskilde University, Denmark.

Stem cells in the bone marrow differentiate to ultimately become mature, functioning blood cells through a tightly regulated process (hematopoiesis) including a stem cell niche interaction and feedback through the immune system. Mutations in a hematopoietic stem cell can create a cancer stem cell leading to a less controlled production of malfunctioning cells in the hematopoietic system. This was mathematically modelled by Andersen et al. Read More

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http://dx.doi.org/10.1016/j.mbs.2020.108372DOI Listing

On Solving Groundwater Flow and Transport Models with Algebraic Multigrid Preconditioning.

Ground Water 2020 May 20. Epub 2020 May 20.

Regional Water Centre of Maghreb, LIMEN, Ecole Mohammadia d'Ingénieurs, Université Mohammed V de Rabat, B.P. 765, Agdal Rabat, Morocco.

Iterative solvers preconditioned with algebraic multigrid have been devised as an optimal technology to speed up the response of large sparse linear systems. In this work, this technique was implemented in the framework of the dual delineation approach. This involves a single groundwater flow linear solution and a pure advective transport solution with different right-hand sides. Read More

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http://dx.doi.org/10.1111/gwat.13016DOI Listing

Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model.

Front Physiol 2020 5;11:306. Epub 2020 May 5.

Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany.

Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. Read More

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http://dx.doi.org/10.3389/fphys.2020.00306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7214688PMC

Preliminary effects of treating the half of high latent hyperopia on refractive and visual results of femtosecond laser-assisted in situ keratomileusis in subjects with hyperopia.

Int Ophthalmol 2020 May 19. Epub 2020 May 19.

Department of Ophthalmology, TOBB ETU, Ankara, Turkey.

Background: To evaluate the preliminary effects of treating the half of high latent hyperopia on refractive and visual outcomes of femtosecond laser-assisted in situ keratomileusis (LASIK) in young subjects with hyperopia.

Methods: This non-randomized comparative study includes 120 eyes of 60 subjects who underwent femtosecond LASIK to correct hyperopia. Group 1 (n = 60) includes subjects with ≤ 1D algebraic difference (DRSE) between cycloplegic (CRSE) and manifest (MRSE) refraction spherical equivalents and was treated by entering manifest refraction values. Read More

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http://dx.doi.org/10.1007/s10792-020-01421-5DOI Listing

Assessing synchronizability provided by coupling variable from the algebraic structure of dynamical systems.

Phys Rev E 2020 Apr;101(4-1):042215

Normandie Université-CORIA, Campus Universitaire du Madrillet, F-76800 Saint-Etienne du Rouvray, France.

Synchronization is a very generic phenomenon which can be encountered in a large variety of coupled dynamical systems. Being able to synchronize chaotic systems is strongly dependent on the nature of their coupling. Few attempts to explain such a dependency using observability and/or controllability were not fully satisfactory and synchronizability yet remained unexplained. Read More

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http://dx.doi.org/10.1103/PhysRevE.101.042215DOI Listing

Molière maximum likelihood proton path estimation approximated by cubic Bézier curve for scatter corrected proton CT reconstruction.

Phys Med Biol 2020 May 18. Epub 2020 May 18.

Electrical and Electronic Engineering, University of Surrey, Guildford, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.

A maximum likelihood approach to the problem of calculating the proton paths inside the scanned object in proton computed tomography is presented. Molière theory is used for first time to derive a physical model that describes proton multiple Coulomb scattering, avoiding the need for the Gaussian approximation currently used. To enable this, the proposed method approximates proton paths with cubic Bézier curves and subsequently maximizes the path likelihood through parametric optimization, based on the Molière model. Read More

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http://dx.doi.org/10.1088/1361-6560/ab9413DOI Listing
May 2020
2.761 Impact Factor

Cooperative Adaptive Dynamic Surface Control for a Class of High-Order Stochastic Nonlinear Multiagent Systems.

IEEE Trans Cybern 2020 May 12;PP. Epub 2020 May 12.

This article investigates the consensus tracking problem for high-order stochastic pure-feedback nonlinear multiagent systems (MASs) with dead zones. It should be pointed out that each follower's virtual and actual control items are the power-exponential functions with positive odd numbers instead of linear items. Because of the structural characteristics of the followers' dynamics, a technique called adding a power integrator is used, which effectively overcomes the difficulties of states and dead zone with power-exponential functions. Read More

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http://dx.doi.org/10.1109/TCYB.2020.2986332DOI Listing

Output-Feedback Global Consensus of Discrete-Time Multiagent Systems Subject to Input Saturation via Q-Learning Method.

IEEE Trans Cybern 2020 May 7. Epub 2020 May 7.

This article proposes a Q-learning (QL)-based algorithm for global consensus of saturated discrete-time multiagent systems (DTMASs) via output feedback. According to the low-gain feedback (LGF) theory, control inputs of the saturated DTMASs can avoid the saturation by utilizing the control policies with LGF matrices, which were computed from the modified algebraic Riccati equation (MARE) by requiring the information of system dynamics in most previous works. However, in this article, we first find the lower bound on the real part of Laplacian matrices' nonzero eigenvalues of directed network topologies. Read More

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http://dx.doi.org/10.1109/TCYB.2020.2987385DOI Listing

A thermodynamic model for predicting transient pressure evolution in response to venting and vaporization of liquefied gas under sudden release.

J Hazard Mater 2020 Aug 3;395:122460. Epub 2020 Mar 3.

Haier Home Appliance R&D Center, Shanghai, 200240, China.

Liquefied gases in energy supply chain suffer the risks of disastrous accidents (e.g. boiling liquid expanding vapor explosion) normally resulted from a sudden release. Read More

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http://dx.doi.org/10.1016/j.jhazmat.2020.122460DOI Listing

Minimal Solvers for Rectifying from Radially-Distorted Conjugate Translations.

IEEE Trans Pattern Anal Mach Intell 2020 May 4. Epub 2020 May 4.

This paper introduces minimal solvers that jointly solve for radial lens undistortion and affine-rectification using local features extracted from the image of coplanar translated and reflected scene texture, which is common in man-made environments. The proposed solvers accommodate different types of local features and sampling strategies, and three of the proposed variants require just one feature correspondence. State-of-the-art techniques from algebraic geometry are used to simplify the formulation of the solvers. Read More

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http://dx.doi.org/10.1109/TPAMI.2020.2992261DOI Listing

Analytical nuclear gradients for electron-attached and electron-detached states for the second-order algebraic diagrammatic construction scheme combined with frozen-density embedding.

J Chem Phys 2020 May;152(17):174109

Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), P.O. Box 6980, D-76049 Karlsruhe, Germany.

In the present work, we report the derivation and implementation of vertical ionization potentials (IPs) and electron affinities (EAs) for embedded wavefunction methods as well as the corresponding analytical nuclear gradients. Vertical transitions have been implemented for CIS(D), the second-order algebraic diagrammatic construction [ADC(2)] scheme, and the second-order approximate coupled-cluster singles and doubles method. For all methods, density fitting is applied to facilitate reduced memory and disk storage requirements. Read More

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http://dx.doi.org/10.1063/5.0002851DOI Listing

Exact Nonequilibrium Steady State of Open XXZ/XYZ Spin-1/2 Chain with Dirichlet Boundary Conditions.

Phys Rev Lett 2020 Apr;124(16):160403

Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.

We investigate a dissipatively driven XYZ spin-1/2 chain in the Zeno limit of strong dissipation, described by the Lindblad master equation. The nonequilibrium steady state is expressed in terms of a matrix product ansatz using novel site-dependent Lax operators. The components of Lax operators satisfy a simple set of linear recurrence equations that generalize the defining algebraic relations of the quantum group U_{q}(sl_{2}). Read More

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http://dx.doi.org/10.1103/PhysRevLett.124.160403DOI Listing

Quantitative three-dimensional nondestructive imaging of whole anaerobic ammonium-oxidizing bacteria.

J Synchrotron Radiat 2020 May 17;27(Pt 3):753-761. Epub 2020 Apr 17.

Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400045, People's Republic of China.

Anaerobic ammonium-oxidizing (anammox) bacteria play a key role in the global nitrogen cycle and in nitrogenous wastewater treatment. The anammox bacteria ultrastructure is unique and distinctly different from that of other prokaryotic cells. The morphological structure of an organism is related to its function; however, research on the ultrastructure of intact anammox bacteria is lacking. Read More

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http://dx.doi.org/10.1107/S1600577520002349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7285686PMC
May 2020
2.736 Impact Factor

Analytic regularity and stochastic collocation of high-dimensional Newton iterates.

Adv Comput Math 2020 Mar 4;46(3). Epub 2020 May 4.

Department of Mathematics and Statistics, Boston University, 111 Cummington Mall, Boston MA 02215.

In this paper we introduce concepts from uncertainty quantification (UQ) and numerical analysis for the efficient evaluation of stochastic high dimensional Newton iterates. In particular, we develop complex analytic regularity theory of the solution with respect to the random variables. This justifies the application of sparse grids for the computation of statistical measures. Read More

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http://dx.doi.org/10.1007/s10444-020-09791-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7201586PMC

Algebraic Study of diatomic Molecules: homonuclear molecules H and N.

Sci Rep 2020 May 6;10(1):7663. Epub 2020 May 6.

Department of Theoretical Physics and Astrophysics, University of Tabriz, Tabriz, 51664, Iran.

It is the aim of this study to discuss for two-body systems like homonuclear molecules in which eigenvalues and eigenfunctions are obtained by exact solutions of the solvable models based on SU(1, 1) Lie algebras. Exact solutions of the solvable Hamiltonian regarding the relative motion in a two-body system on Lie algebras were obtained. The U(1) ↔ O(2), U(3) ↔ O(4) and U(3) ↔ O(4) transitional Hamiltonians are employed to described for H and N molecules. Read More

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http://dx.doi.org/10.1038/s41598-020-64266-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7203175PMC

Dominant rule of community effect in synchronized beating behavior of cardiomyocyte networks.

Authors:
Kenji Yasuda

Biophys Rev 2020 Apr 4;12(2):481-501. Epub 2020 May 4.

Department of Physics, School of Advanced Science and Engineering, Waseda University 3-4-1 Okubo, Shinjuku-ku, Tokyo, 169-8555, Japan.

Exploiting the combination of latest microfabrication technologies and single cell measurement technologies, we can measure the interactions of single cells, and cell networks from "algebraic" and "geometric" perspectives under the full control of their environments and interactions. However, the experimental constructive single cell-based approach still remains the limitations regarding the quality and condition control of those cells. To overcome these limitations, mathematical modeling is one of the most powerful complementary approaches. Read More

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http://dx.doi.org/10.1007/s12551-020-00688-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242600PMC

Robustness and parameter geography in post-translational modification systems.

PLoS Comput Biol 2020 May 4;16(5):e1007573. Epub 2020 May 4.

Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America.

Biological systems are acknowledged to be robust to perturbations but a rigorous understanding of this has been elusive. In a mathematical model, perturbations often exert their effect through parameters, so sizes and shapes of parametric regions offer an integrated global estimate of robustness. Here, we explore this "parameter geography" for bistability in post-translational modification (PTM) systems. Read More

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http://dx.doi.org/10.1371/journal.pcbi.1007573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224580PMC