scholarly journals Nonlinear Memory Capacity of Parallel Time-Delay Reservoir Computers in the Processing of Multidimensional Signals

2016 ◽  
Vol 28 (7) ◽  
pp. 1411-1451 ◽  
Author(s):  
Lyudmila Grigoryeva ◽  
Julie Henriques ◽  
Laurent Larger ◽  
Juan-Pablo Ortega
Keyword(s):  
Finite Sample ◽  
Functional Link ◽  
Nonlinear Memory ◽  
Reservoir Architecture ◽  
Multidimensional Signals ◽  
Input Signals ◽  
Reservoir Design ◽  
Ridge Regression Estimator ◽  
The Impact ◽  
Theoretical Results

This letter addresses the reservoir design problem in the context of delay-based reservoir computers for multidimensional input signals, parallel architectures, and real-time multitasking. First, an approximating reservoir model is presented in those frameworks that provides an explicit functional link between the reservoir architecture and its performance in the execution of a specific task. Second, the inference properties of the ridge regression estimator in the multivariate context are used to assess the impact of finite sample training on the decrease of the reservoir capacity. Finally, an empirical study is conducted that shows the adequacy of the theoretical results with the empirical performances exhibited by various reservoir architectures in the execution of several nonlinear tasks with multidimensional inputs. Our results confirm the robustness properties of the parallel reservoir architecture with respect to task misspecification and parameter choice already documented in the literature.

scholarly journals Mean Empirical Likelihood Inference for Response Mean with Data Missing at Random

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hanji He ◽  
Guangming Deng
Keyword(s):  
Empirical Likelihood ◽  
Missing At Random ◽  
Confidence Regions ◽  
Likelihood Inference ◽  
High Dimensional ◽  
Finite Sample ◽  
The Mean ◽  
Data Missing ◽  
Consistency And Asymptotic Normality ◽  
The Impact

We extend the mean empirical likelihood inference for response mean with data missing at random. The empirical likelihood ratio confidence regions are poor when the response is missing at random, especially when the covariate is high-dimensional and the sample size is small. Hence, we develop three bias-corrected mean empirical likelihood approaches to obtain efficient inference for response mean. As to three bias-corrected estimating equations, we get a new set by producing a pairwise-mean dataset. The method can increase the size of the sample for estimation and reduce the impact of the dimensional curse. Consistency and asymptotic normality of the maximum mean empirical likelihood estimators are established. The finite sample performance of the proposed estimators is presented through simulation, and an application to the Boston Housing dataset is shown.

scholarly journals Dynamics of the rumor-spreading model with hesitation mechanism in heterogenous networks and bilingual environment

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Shuai Yang ◽  
Haijun Jiang ◽  
Cheng Hu ◽  
Juan Yu ◽  
Jiarong Li
Keyword(s):  
Lyapunov Method ◽  
Reproduction Number ◽  
Model Parameters ◽  
Rumor Spreading ◽  
Spreading Model ◽  
Reductio Ad Absurdum ◽  
The Stability ◽  
The Impact ◽  
Theoretical Results ◽  
The Basic Reproduction Number

Abstract In this paper, a novel rumor-spreading model is proposed under bilingual environment and heterogenous networks, which considers that exposures may be converted to spreaders or stiflers at a set rate. Firstly, the nonnegativity and boundedness of the solution for rumor-spreading model are proved by reductio ad absurdum. Secondly, both the basic reproduction number and the stability of the rumor-free equilibrium are systematically discussed. Whereafter, the global stability of rumor-prevailing equilibrium is explored by utilizing Lyapunov method and LaSalle’s invariance principle. Finally, the sensitivity analysis and the numerical simulation are respectively presented to analyze the impact of model parameters and illustrate the validity of theoretical results.

scholarly journals Statistical Inference for the Beta Coefficient

Risks ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 56 ◽  
Author(s):  
Taras Bodnar ◽  
Arjun K. Gupta ◽  
Valdemar Vitlinskyi ◽  
Taras Zabolotskyy
Keyword(s):  
Confidence Interval ◽  
Empirical Study ◽  
Crucial Role ◽  
Risk Measure ◽  
Statistical Test ◽  
Asymptotic Distributions ◽  
Finite Sample ◽  
Benchmark Portfolio ◽  
Beta Coefficient ◽  
Theoretical Results

The beta coefficient plays a crucial role in finance as a risk measure of a portfolio in comparison to the benchmark portfolio. In the paper, we investigate statistical properties of the sample estimator for the beta coefficient. Assuming that both the holding portfolio and the benchmark portfolio consist of the same assets whose returns are multivariate normally distributed, we provide the finite sample and the asymptotic distributions of the sample estimator for the beta coefficient. These findings are used to derive a statistical test for the beta coefficient and to construct a confidence interval for the beta coefficient. Moreover, we show that the sample estimator is an unbiased estimator for the beta coefficient. The theoretical results are implemented in an empirical study.

scholarly journals RIPK3 acts as a lipid metabolism regulator contributing to inflammation and carcinogenesis in non-alcoholic fatty liver disease

Gut ◽  
2020 ◽  
pp. gutjnl-2020-321767
Author(s):  
Marta B Afonso ◽  
Pedro M Rodrigues ◽  
Miguel Mateus-Pinheiro ◽  
André L Simão ◽  
Maria M Gaspar ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Fatty Liver Disease ◽  
Body Weight Gain ◽  
Control Diet ◽  
Peroxisome Proliferator ◽  
Functional Link ◽  
Alcoholic Fatty Liver ◽  
The Impact ◽  
Alcoholic Fatty Liver Disease

ObjectiveReceptor-interacting protein kinase 3 (RIPK3) is a key player in necroptosis execution and an emerging metabolic regulator, whose contribution to non-alcoholic fatty liver disease (NAFLD) is controversial. We aimed to clarify the impact of RIPK3 signalling in the pathogenesis of human and experimental NAFLD.DesignRIPK3 levels were evaluated in two large independent cohorts of patients with biopsy proven NAFLD diagnosis and correlated with clinical and biochemical parameters. Wild-type (WT) or Ripk3-deficient (Ripk3−/−) mice were fed a choline-deficient L-amino acid-defined diet (CDAA) or an isocaloric control diet for 32 and 66 weeks.ResultsRIPK3 increased in patients with non-alcoholic steatohepatitis (NASH) in both cohorts, correlating with hepatic inflammation and fibrosis. Accordingly, Ripk3 deficiency ameliorated CDAA-induced inflammation and fibrosis in mice at both 32 and 66 weeks. WT mice on the CDAA diet for 66 weeks developed preneoplastic nodules and displayed increased hepatocellular proliferation, which were reduced in Ripk3−/− mice. Furthermore, Ripk3 deficiency hampered tumourigenesis. Intriguingly, Ripk3−/− mice displayed increased body weight gain, while lipidomics showed that deletion of Ripk3 shifted hepatic lipid profiles. Peroxisome proliferator-activated receptor γ (PPARγ) was increased in Ripk3−/− mice and negatively correlated with hepatic RIPK3 in patients with NAFLD. Mechanistic studies established a functional link between RIPK3 and PPARγ in controlling fat deposition and fibrosis.ConclusionHepatic RIPK3 correlates with NAFLD severity in humans and mice, playing a key role in managing liver metabolism, damage, inflammation, fibrosis and carcinogenesis. Targeting RIPK3 and its intricate signalling arises as a novel promising approach to treat NASH and arrest disease progression.

scholarly journals Synchrony in networks of Franklin bells

2019 ◽  
Vol 84 (5) ◽  
pp. 1001-1021 ◽  
Author(s):  
Mustafa Şayli ◽  
Yi Ming Lai ◽  
Rüdiger Thul ◽  
Stephen Coombes
Keyword(s):  
Linear Stability ◽  
Benjamin Franklin ◽  
Stability Function ◽  
Impact Oscillators ◽  
Network Topologies ◽  
Network States ◽  
Low Dimensional ◽  
Oscillatory Network ◽  
The Impact ◽  
Theoretical Results

Abstract The Franklin bell is an electro-mechanical oscillator that can generate a repeating chime in the presence of an electric field. Benjamin Franklin famously used it as a lightning detector. The chime arises from the impact of a metal ball on a metal bell. Thus, a network of Franklin bells can be regarded as a network of impact oscillators. Although the number of techniques for analysing impacting systems has grown in recent years, this has typically focused on low-dimensional systems and relatively little attention has been paid to networks. Here we redress this balance with a focus on synchronous oscillatory network states. We first study a single Franklin bell, showing how to construct periodic orbits and how to determine their linear stability and bifurcation. To cope with the non-smooth nature of the impacts we use saltation operators to develop the correct Floquet theory. We further introduce a new smoothing technique that circumvents the need for saltation and that recovers the saltation operators in some appropriate limit. We then consider the dynamics of a network of Franklin bells, showing how the master stability function approach can be adapted to treat the linear stability of the synchronous state for arbitrary network topologies. We use this to determine conditions for network induced instabilities. Direct numerical simulations are shown to be in excellent agreement with theoretical results.

Experimental and theoretical results on electron emission from helium by the impact of bare Li3+ions

2012 ◽  
Vol 45 (14) ◽  
pp. 145202 ◽  
Author(s):  
J M Monti ◽  
D Fregenal ◽  
S Suárez ◽  
P D Fainstein ◽  
R D Rivarola ◽  
...  
Keyword(s):  
Electron Emission ◽  
The Impact ◽  
Theoretical Results

Research on the Iron Losses in Variable-Frequency Motor

2014 ◽  
Vol 494-495 ◽  
pp. 1482-1486
Author(s):  
Xiao Li Luo ◽  
Wan Tai Liu ◽  
Hui Fang Zhou ◽  
Sheng Hua Luo
Keyword(s):  
Skin Effect ◽  
High Accuracy ◽  
Variable Frequency ◽  
Test Results ◽  
Analysis Method ◽  
Iron Losses ◽  
Prototype Test ◽  
Harmonic Analysis Method ◽  
The Impact ◽  
Theoretical Results

In this paper, faced with the modeling problems of analysis and calculation for iron losses in variable-frequency motor under no-sinusoidal excitation, the author points out a method that the iron losses can be calculated under any magnetic field ,that is waveform-Harmonic analysis method. In consideration of the impact of Power supply harmonics, Core saturation and Skin Effect, the author proposes a new parameter -- Harmonic Loss Correction Factor. From the comparisons between the prototype test results and the theoretical results show that this method has high accuracy and strong feasibility.

scholarly journals The Impact of Cost Uncertainty on Cournot Duopoly Game with Concave Demand Function

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
S. S. Askar
Keyword(s):  
Optimization Problem ◽  
Demand Function ◽  
Equilibrium Points ◽  
Cournot Duopoly ◽  
Worst Case ◽  
Dynamical Characteristics ◽  
Inflection Points ◽  
The Cost ◽  
The Impact ◽  
Theoretical Results

It is reported in the literature that the most fundamental idea to address uncertainty is to begin by condensing random variables. In this paper, we propose Cournot duopoly game where quantity-setting firms use nonlinear demand function that has no inflection points. A random cost function is introduced in this model. Each firm in the model wants to maximize its expected profit and also wants to minimize its uncertainty by minimizing the cost. To handle this multiobjective optimization problem, the expectation and worst-case approaches are used. A model of two rational firms that are in competition and produce homogenous commodities is introduced using an unknown demand function. The equilibrium points of this model are obtained and their dynamical characteristics such as stability, bifurcation, and chaos are investigated. Complete stability and bifurcation analysis are provided. The obtained theoretical results are verified by numerical simulation.

An Analytical Poroelastic Model of a Nonhomogeneous Medium Under Creep Compression for Ultrasound Poroelastography Applications—Part I

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Md Tauhidul Islam ◽  
J. N. Reddy ◽  
Raffaella Righetti
Keyword(s):  
Soft Tissue Tumor ◽  
Fluid Pressure ◽  
Cylindrical Sample ◽  
Surrounding Tissue ◽  
Finite Element Models ◽  
Mechanical Parameters ◽  
Poroelastic Model ◽  
The Impact ◽  
Analytical Expressions ◽  
Theoretical Results

An analytical theory for the unconfined creep behavior of a cylindrical inclusion (simulating a soft tissue tumor) embedded in a cylindrical background sample (simulating normal tissue) is presented and analyzed in this paper. Both the inclusion and the background are considered as fluid-filled, porous materials, each of them being characterized by a set of mechanical properties. Specifically, in this paper, the inclusion is considered to be less permeable than the background. The cylindrical sample is compressed using a constant pressure within two frictionless plates and is allowed to expand in an unconfined way along the radial direction. Analytical expressions for the effective Poisson's ratio (EPR) and fluid pressure inside and outside the inclusion are derived and analyzed. The theoretical results are validated using finite element models (FEMs). Statistical analysis shows excellent agreement between the results obtained from the developed model and the results from FEM. Thus, the developed theoretical model can be used in medical imaging modalities such as ultrasound poroelastography to extract the mechanical parameters of tissues and/or to better understand the impact of different mechanical parameters on the estimated displacements, strains, stresses, and fluid pressure inside a tumor and in the surrounding tissue.

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