Asymptotic behavior of age-structured and delayed Lotka-Volterra models

In this work we investigate some asymptotic properties of an age-structured Lotka-Volterra model, where a specific choice of the functional parameters allows us to formulate it as a delayed problem, for which we prove the existence of a unique coexistence equilibrium and characterize the existence of a periodic solution. We also exhibit a Lyapunov functional that enables us to reduce the attractive set to either the nontrivial equilibrium or to a periodic solution. We then prove the asymptotic stability of the nontrivial equilibrium where, depending on the existence of the periodic trajectory, we make explicit the basin of attraction of the equilibrium. Finally, we prove that these results can be extended to the initial PDE problem.Comment: 29 page

On magnetic leaf-wise intersections

In this article we introduce the notion of a magnetic leaf-wise intersection point which is a generalization of the leaf-wise intersection point with magnetic effects. We also prove the existence of magnetic leaf-wise intersection points under certain topological assumptions.Comment: 43 page

Coupled deconvolution for frequency extrapolation of electromagnetic solutions with matrix pencil method

Matrix pencil method (MPM) has been widely used to estimate the parameters of complex-exponential based models. An important application is the extrapolation of the frequency-domain solutions of electromagnetic problems. In this paper, we present a mathematical tool, namely, coupled deconvolution, which improves the performance of the MPM-based extrapolation of electromagnetic solutions. © 2005 IEEE

Coupled matrix pencil method for frequency extrapolation of electromagnetic solutions

Matrix pencil method (MPM) is used to extrapolate the available electromagnetic solutions in frequency domain to estimate the high-frequency solutions. A new approach, namely, coupled MPM, is introduced to obtain the electromagnetic solutions at intermediate frequencies using the available low-frequency and high-frequency data. © 2005 IEEE

Childhood obesity- diagnostic methods, prevalence and etiology

Çocukluk çağı obezitesi de erişkin obezitesi gibi artan bir prevalansa sahiptir. Bu artan prevalansın nedeni olarak diyet kompozisyonundaki değişiklik ve hareket miktarındaki azalma sorumlu tutulmaktadır.Ayrıca hem ailelerin ve hem de hekimlerin obeziteyi tedavi etme gereğini göz ardı etmekte olmaları ve değişen yaşam şartları obeziteyi yaygın bir sağlık sorunu haline getirmektedir. Obezite önümüzdeki yılların önemli bir halk sağlığı problemi olmaya devam edecek gibi görünmektedir.Just like increase in adult obesity, the prevalence of childhood obesity is also on the rise. Changes in dietary composition and a decrease in the amount of motion are held responsible for this increase in prevalence. Apart from these, obesity is becoming a common health problem because of changing life styles and the lack of treatment due to the ignorence of both parents and physicians. Obesity seems to continue to be an important public health problem in future

An efficient method for electromagnetic characterization of 2-D geometries in stratified media

A numerically efficient technique, based on the spectral-domain method of moments (MoM) in conjunction with the generalized pencil-of-functions (GPOF) method, is developed for the characterization of two-dimensional geometries in multilayer planar media. This approach provides an analytic expression for all the entries of the MoM matrix, explicitly including the indexes of the basis and testing functions provided that the Galerkin's MoM is employed. This feature facilitates an efficient modification of the geometry without the necessity of recalculating the additional elements in the MoM matrix. To assess the efficiency of the approach, the results and the matrix fill times are compared to those obtained with two other efficient methods, namely, the spatial-domain MoM in conjunction with the closed-form Green's functions, and a fast Fourier transform algorithm to evaluate the MoM matrix entries. Among these, the spectral-domain MoM using the GPOF algorithm is the most efficient approach for printed multilayer geometries

Integrable boundary conditions for the Toda lattice

The problem of construction of the boundary conditions for the Toda lattice compatible with its higher symmetries is considered. It is demonstrated that this problem is reduced to finding of the differential constraints consistent with the ZS-AKNS hierarchy. A method of their construction is offered based on the B\"acklund transformations. It is shown that the generalized Toda lattices corresponding to the non-exceptional Lie algebras of finite growth can be obtained by imposing one of the four simplest integrable boundary conditions on the both ends of the lattice. This fact allows, in particular, to solve the problem of reduction of the series $A$ Toda lattices into the series $D$ ones. Deformations of the found boundary conditions are presented which leads to the Painlev\'e type equations. Key words: Toda lattice, boundary conditions, integrability, B\"acklund transformation, Lie algebras, Painlev\'e equation

Validation through comparison: Measurement and calculation of the bistatic radar cross section of a stealth target

Bistatic radar cross section (BRCS) values of a stealth airborne target are predicted by performing both scaled-model measurements and numerical simulations. In order to achieve the solution of large-scale electromagnetic problems in the numerical simulation environment, the fast multipole method (FMM) is implemented and used. The FMM has produced remarkably accurate results, in addition to its efficiency. The efficiency of the FMM is due to its reduced computational complexity and memory requirement, which are both O(N1.5). Comparison of the measured and computed BRCS values has resulted in a striking agreement, which serves to validate both of the prediction techniques