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Dynamic linear model

Xujun Yang, Chuandong Li, Qiankun Song, Jiyang Chen, Junjian Huang
This paper talks about the stability and synchronization problems of fractional-order quaternion-valued neural networks (FQVNNs) with linear threshold neurons. On account of the non-commutativity of quaternion multiplication resulting from Hamilton rules, the FQVNN models are separated into four real-valued neural network (RVNN) models. Consequently, the dynamic analysis of FQVNNs can be realized by investigating the real-valued ones. Based on the method of M-matrix, the existence and uniqueness of the equilibrium point of the FQVNNs are obtained without detailed proof...
May 4, 2018: Neural Networks: the Official Journal of the International Neural Network Society
Kunihiko Kaneko, Chikara Furusawa
We present a macroscopic theory to characterize the plasticity, robustness, and evolvability of biological responses and their fluctuations. First, linear approximation in intracellular reaction dynamics is used to demonstrate proportional changes in the expression of all cellular components in response to a given environmental stress, with the proportion coefficient determined by the change in growth rate as a consequence of the steady growth of cells. We further demonstrate that this relationship is supported through adaptation experiments of bacteria, perhaps too well as this proportionality is held even across cultures of different types of conditions...
May 20, 2018: Annual Review of Biophysics
Hujun Shen, Mingsen Deng, Zhenhua Wu, Jihua Zhang, Yachao Zhang, Chengui Gao, Chao Cen
The effect of cholesterol on membrane dipole potential has been the subject of a great number of experimental and theoretical investigations, but these studies have yielded different findings and interpretations at high cholesterol concentrations. This suggests that the underlying mechanism of the cholesterol effect is not well addressed. Moreover, as far as we know, none of the previously proposed coarse-grained (CG) models (including MARTINI and its improved versions) has been successfully used to probe the effect of cholesterol on membrane dipole potential, owing to either an inaccurate description of water-cholesterol electrostatics or the neglect of the contribution of cholesterol to membrane dipole potential...
May 23, 2018: Journal of Chemical Theory and Computation
Natacha Go, Catherine Belloc, Caroline Bidot, Suzanne Touzeau
Understanding the impact of pathogen exposure on the within-host dynamics and its outcome in terms of infectiousness is a key issue to better understand and control the infection spread. Most experimental and modelling studies tackling this issue looked at the impact of the exposure dose on the infection probability and pathogen load, very few on the within-host immune response. Our aim was to explore the impact on the within-host response not only of the exposure dose, but also of its duration and peak, for contrasted virulence levels...
May 21, 2018: Mathematical Medicine and Biology: a Journal of the IMA
Sandra K Hnat, Ben J H van Basten, Antonie J van den Bogert
Force plates for human movement analysis provide accurate measurements when mounted rigidly on an inertial reference frame. Large measurement errors occur, however, when the force plate is accelerated, or tilted relative to gravity. This prohibits the use of force plates in human perturbation studies with controlled surface movements, or in conditions where the foundation is moving or not sufficiently rigid. Here we present a linear model to predict the inertial and gravitational artifacts using accelerometer signals...
May 19, 2018: Journal of Biomechanics
Juan Carlos López Alfonso, Shireen Parsai, Nikhil Joshi, Andrew Godley, Chirag Shah, Shlomo A Koyfman, Jimmy J Caudell, Clifton D Fuller, Heiko Enderling, Jacob G Scott
PURPOSE: Intensity modulated radiation therapy (IMRT) has allowed optimization of three-dimensional spatial radiation dose distributions permitting target coverage while reducing normal tissue toxicity. However, radiation-induced normal tissue toxicity is a major contributor to patients' quality of life and often a dose-limiting factor in the definitive treatment of cancer with radiation therapy. We propose the next logical step in the evolution of IMRT using canonical radiobiological principles, optimizing the temporal dimension through which radiation therapy is delivered to further reduce radiation-induced toxicity by increased time for normal tissue recovery...
May 22, 2018: Medical Physics
Abhishek Sahu, Youngmin Hwang, Cristian Vilos, Jong-Min Lim, Sunghyun Kim, Won Il Choi, Giyoong Tae
The calcium (Ca2+) ion concentration in the blood serum is tightly regulated, and any abnormalities in the level of serum calcium ions are associated with many potentially dangerous diseases. Thus, monitoring of the Ca2+ ion concentration in the blood serum is of fundamental importance. Gold nanoparticle (GNP)-based colorimetric biosensors have enormous potential in clinical diagnostic applications due to their simplicity, versatility, and unique optical properties. In this study, we have developed an alendronate functionalized gold nanoparticle (GNP-ALD) system for the measurement of Ca2+ ion concentration in biological samples...
May 22, 2018: Nanoscale
Markus Gross, Fathollah Varnik
Flow behavior of a single-component yield stress fluid is addressed on the hydrodynamic level. A basic ingredient of the model is a coupling between fluctuations of density and velocity gradient via a Herschel-Bulkley-type constitutive model. Focusing on the limit of low shear rates and high densities, the model approximates well-but is not limited to-gently sheared hard sphere colloidal glasses, where solvent effects are negligible. A detailed analysis of the linearized hydrodynamic equations for fluctuations and the resulting cubic dispersion relation reveals the existence of a range of densities and shear rates with growing flow heterogeneity...
May 22, 2018: Soft Matter
Janani Sampath, Lisa M Hall
We simulate a single spherical nanoparticle (NP) surrounded by partially neutralized ionomers. The coarse-grained ionomers consist of a linear backbone of neutral monomer beads with charged pendant beads and counterions, along with pendant 'sticker' beads that represent unneutralized acid groups. Two different NP interactions are considered; one in which the NP interacts uniformly with all beads in the system (neutral NP) and another in which the NP has higher cohesive interactions with ions and stickers (sticky NP)...
May 22, 2018: Soft Matter
Adrian Kastler, Hannes Gruber, Elke Gizewski, Alexander Loizides
BACKGROUND AND OBJECTIVES: Real-time ice-ball formation during cryoneurolysis has sparsely been assessed with ultrasound (US). Cryoneurolysis in lower back pain syndrome represents a validated management option in cases of facet joint syndrome. Ultrasound may be a useful tool to perform facet joint cryodenervation. The objective of this study was to assess, ex vivo, the ability of US to assess the ice-ball formation of a cryoneurolysis device. METHODS: Ultrasound assessment of the ice-ball depiction was done using chicken muscle at 22°C in which several freezing cycles were performed with both 2...
May 17, 2018: Regional Anesthesia and Pain Medicine
Yong-Lei Wang, You-Liang Zhu, Zhong-Yuan Lu, Aatto Laaksonen
Computer simulations provide a unique insight into the microscopic details, molecular interactions and dynamic behavior responsible for many distinct physicochemical properties of ionic liquids. Due to the sluggish and heterogeneous dynamics and the long-ranged nanostructured nature of ionic liquids, coarse-grained meso-scale simulations provide an indispensable complement to detailed first-principles calculations and atomistic simulations allowing studies over extended length and time scales with a modest computational cost...
May 21, 2018: Soft Matter
René Weber, Bradly Alicea, Richard Huskey, Klaus Mathiak
This study investigates the dynamics of attention during continuous, naturalistic interactions in a video game. Specifically, the effect of repeated distraction on a continuous primary task is related to a functional model of network connectivity. We introduce the Non-linear Attentional Saturation Hypothesis (NASH), which predicts that effective connectivity within attentional networks increases non-linearly with decreasing distraction over time, and exhibits dampening at critical parameter values. Functional magnetic resonance imaging (fMRI) data collected using a naturalistic behavioral paradigm coupled with an interactive video game is used to test the hypothesis...
2018: Frontiers in Human Neuroscience
F L Dunne, M M Kelleher, S W Walsh, D P Berry
Genetic evaluations decompose an observed phenotype into its genetic and nongenetic components; the former are termed BLUP with the solutions for the systematic environmental effects in the statistical model termed best linear unbiased estimates (BLUE). Geneticists predominantly focus on the BLUP and rarely consider the BLUE. The objective of this study, however, was to define and quantify the association between 8 herd-level characteristics and BLUE for 6 traits in dairy herds, namely (1) age at first calving, (2) calving to first service interval (CFS), (3) number of services, (4) calving interval (CIV), (5) survival, and (6) milk yield...
May 16, 2018: Journal of Dairy Science
Adora M DSouza, Anas Z Abidin, Udaysankar Chockanathan, Giovanni Schifitto, Axel Wismüller
Functional connectivity analysis of functional MRI (fMRI) can represent brain networks and reveal insights into interactions amongst different brain regions. However, most connectivity analysis approaches adopted in practice are linear and non-directional. In this paper, we demonstrate the advantage of a data-driven, directed connectivity analysis approach called Mutual Connectivity Analysis using Local Models (MCA-LM) that approximates connectivity by modeling nonlinear dependencies of signal interaction, over more conventionally used approaches, such as Pearson's and partial correlation, Patel's conditional dependence measures, etcetera...
May 16, 2018: NeuroImage
Nicole Wake, Hersh Chandarana, Henry Rusinek, Koji Fujimoto, Linda Moy, Daniel K Sodickson, Sungheon Gene Kim
INTRODUCTION: Pharmacokinetic parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) data are sensitive to acquisition and post-processing techniques, which makes it difficult to compare results obtained using different methods. In particular, one of the most important factors affecting estimation of model parameters is how to convert MRI signal intensities to contrast agent concentration. The purpose of our study was to quantitatively compare a linear signal-to-concentration conversion (LC) as an approximation and a non-linear conversion (NLC) based on the MRI signal equation, in terms of the accuracy and precision of the pharmacokinetic parameters in T1 -weighted DCE-MRI...
May 16, 2018: Magnetic Resonance Imaging
Sameer Shakeel Ansari, Imtiyaz Yousuf, Farukh Arjmand, Mohammad Khursheed Siddiqi, Saeeda Naqvi
The intermolecular interaction of flufenamic acid (Hfluf) with two model proteins i.e., hemoglobin and lysozyme was explored using fluorescence, UV-vis, circular dichroism, DLS, and molecular docking techniques. The corroborative spectroscopic techniques suggested efficient binding of Hfluf to both the proteins. The S-V plot in Hb-Hfluf system showed positive deviation highlighting the presence of both static and dynamic quenching. Hence, ground state complex model and sphere of action quenching model were used for the study...
May 16, 2018: International Journal of Biological Macromolecules
Harshad Sanjay Gaikwad, Pranab Kumar Mondal, Somchai Wongwises
In this article, we describe the electro-hydrodynamics of non-Newtonian fluid in narrow fluidic channel with solvent permeable and ion-penetrable polyelectrolyte layer (PEL) grafted on channel surface with an interaction of non-overlapping electric double layer (EDL) phenomenon. In this analysis, we integrate power-law model in the momentum equation for describing the non-Newtonian rheology. The complex interplay between the non-Newtonian rheology and interfacial electrochemistry in presence of PEL on the walls leads to non-intuitive variations in the underlying flow dynamics in the channels...
May 18, 2018: Scientific Reports
Rachel Nicks, Lucie Chambon, Stephen Coombes
For coupled oscillator networks with Laplacian coupling, the master stability function (MSF) has proven a particularly powerful tool for assessing the stability of the synchronous state. Using tools from group theory, this approach has recently been extended to treat more general cluster states. However, the MSF and its generalizations require the determination of a set of Floquet multipliers from variational equations obtained by linearization around a periodic orbit. Since closed form solutions for periodic orbits are invariably hard to come by, the framework is often explored using numerical techniques...
March 2018: Physical Review. E
Urna Basu, Laurent Helden, Matthias Krüger
Nonlinear response theory, in contrast to linear cases, involves (dynamical) details, and this makes application to many-body systems challenging. From the microscopic starting point we obtain an exact response theory for a small number of coarse-grained degrees of freedom. With it, an extrapolation scheme uses near-equilibrium measurements to predict far-from-equilibrium properties (here, second order responses). Because it does not involve system details, this approach can be applied to many-body systems...
May 4, 2018: Physical Review Letters
M Nsakashalo-Senkwe, E Mwase, E Chizema-Kawesha, V Mukonka, P Songolo, F Masaninga, M P Rebollo, B Thomas, M J Bockarie, H Betts, J R Stothard, L A Kelly-Hope
Lymphatic filariasis (LF) is a mosquito-borne disease, broadly endemic in Zambia, and is targeted for elimination by mass drug administration (MDA) of albendazole and diethylcarbamazine citrate (DEC) to at-risk populations. Anopheline mosquitoes are primary vectors of LF in Africa, and it is possible that the significant scale-up of malaria vector control over the past decade may have also impacted LF transmission, and contributed to a decrease in prevalence in Zambia. We therefore aimed to examine the putative association between decreasing LF prevalence and increasing coverage of insecticide-treated mosquito nets (ITNs) for malaria vector control, by comparing LF mapping data collected between 2003-2005 and 2009-2011 to LF sentinel site prevalence data collected between 2012 and 2014, before any anti-LF MDA was started...
November 2017: Parasite Epidemiology and Control
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