Pursuit on regular surfaces with application to consensus problems

Nonlinear Dynamics - In this work we develop geometric and numerical methods to analyze the behavior of a system of organisms or particles under various types of pursuit on a regular surface. We...     

A numerical approach for a model of the precancer lesions caused by the human papillomavirus

We develop two numerical methods to approximate the solutions of a pioneer model of the lesions at the cervical cells caused by the human papillomavirus. Such model is given by a nonlinear advection–diffusion-reaction partial differential equation and the goal of the schemes is to analyze the behaviour of the evolution of infected cells. The developed schemes consist of two explicit non standard finite differences numerical schemes which satisfy positivity conditions. They are based on the subequation method in the context of the non standard scheme methodology. Our approach provides an alternative method to the early diagnosis of the disease and may open up new lines of research.     

A solution for antiplane‐strain local problems using elliptic integrals of Cauchy type

Quasi‐periodic piecewise analytic solutions, without poles, are found for the local antiplane‐strain problems. Such problems arise from applying the asymptotic homogenization method to an elastic problem in a parallel fiber‐reinforced periodic composite that presents an imperfect contact of spring type between the fiber and the matrix. Our methodology consists of rewriting the contact conditions in a complex appropriate form that allow us to use the elliptic integrals of Cauchy type. Several general conditions are assumed including that the fibers are disposed of arbitrary manner in the unit cell, that all fibers present imperfect contact with different constants of imperfection, and that their cross section is smooth closed arbitrary curves. Finally, we obtain a family of piecewise analytic solutions for the local antiplane‐strain problems that depend of a real parameter. When we vary this parameter, it is possible to improve classic bounds for the effective coefficients. Copyright © 2017 John Wiley & Sons, Ltd.     

Quantitative determination of erythromycin and its hydrolysis products by cyclic voltammetry at the interface between water and 1,2-dichloroethane

An electrochemical method for quantifying erythromycin (Er) salts and their hydrolysis products is described. Cyclic voltammetry at the water/1,2-dichloroethane interface in a four-electrode system was used. A linear relationship between I_p and the erythromycin concentration was obtained up to the solubility limit of the antibiotic. The various hydrolysis products which can be obtained in acid or basic solutions were characterized by their respective transfer potentials. Similar hydrolysis products were observed for aged solutions of Er lactobionate.It is concluded that the proposed method is suitable for the quantification of Er and for distinguishing it from its hydrolysis products.     

Predicted existence of H 3 ++ molecular ions in strong magnetic fields

It is shown by a variational method that the molecular ion H ₃ ⁺⁺ can exist for magnetic fields B< 10¹¹ G. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 800–805 (10 June 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

On the modeling of long-term HIV-1 infection dynamics

In this paper, we propose and study models of long-term Human Immunodeficiency Virus (HIV-1) infection. Our aim is to identify model mechanisms that allow one to explain the trends observed in clinical measurements of the number of CD4+ T-cells and virus throughout the long-term HIV-1 infection, from the acute phase until the onset of AIDS. To achieve our goal, we apply some standard methods of modeling and analysis of dynamical systems. Among these methods, are model development and validation processes such as parameter estimation, as well as Painleve and bifurcation analysis.     

Modeling track-terrain interaction for transient robotic vehicle maneuvers

This article describes integration of a realistic and efficient track-terrain interaction model with a multibody dynamics model of a robotic tracked vehicle. The track-terrain interface continuum is approximated by discretized and parameterizable force elements. Of particular note is a kinematic model used to estimate dynamic shear displacement, taking the form of a partial differential equation. This equation is approximated by a series of ordinary differential equations, making it compatible with multibody dynamics model formulations. Comparisons between simulated results and those obtained from field testing with a remotely-operated unmanned tracked vehicle are made to evaluate the effectiveness of this approach and to validate the use of nominal parameter data from the literature. The test vehicle was subjected to four different types of maneuvers (go-and-stop, j-turn, double lane change, and zero radius turn) on asphalt and dry sand. Simulated results using both the dynamic and steady-state track-terrain interaction models match very well with those obtained from the tests, except for the zero radius turning maneuver in sand. In this case, bulldozing effects must be incorporated to improve prediction of lateral forces.     

A New Nonsymmetric As(OH)3 Species. Comparison with the Known C3 Species and Thermochemistry at the HF,DFT(B3LYP), MP2, MP4, and CCSD(T) Levels of Theory.

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