arXiv subjects

Nguyen Van Minh

Publications and source records attributed to Nguyen Van Minh.

29 records · Page 2Linked to original sources

arXiv2012

Geometry of integrable dynamical systems on 2-dimensional surfaces

This paper is devoted to the problem of classification, up to smooth isomorphisms or up to orbital equivalence, of smooth integrable vector fields on 2-dimensional surfaces, under some nondegeneracy conditions. The main continuous invariants involved in this classification are the left equivalence classes of period or monodromy functions, and the cohomology classes of period cocycles, which can be expressed in terms of Puiseux series. We also study the problem of Hamiltonianization of these integrable vector fields by a compatible symplectic or Poisson structure.

math.DS↗

arXiv2012

On the Asymptotic Behavior of Volterra Difference Equations

We consider the asymptotic behavior of solutions of the difference equations of the form $x(n+1)=Ax(n) + \sum_{k=0}^n B(n-k)x(k) + y(n)$ in a Banach space $\X$, where $n=0,1,2,...$; $A,B(n)$ are linear bounded operator in $\X$. Our method of study is based on the concept of spectrum of a unilateral sequence. The obtained results on asymptotic stability and almost periodicity are stated in terms of spectral properties of the equation and its solutions. To this end, a relation between the Z-transform and spectrum of a unilateral sequence is established. The main results extend previous ones.

math.DS↗

arXiv2010

Traveling wave dispersal in partially sedentary age-structured populations

In this paper we present a thorough study on the existence of traveling waves in a mathematical model of dispersal in a partially sedentary age-structured population. This type of model was first proposed by Veit and Lewis in [{\it Am. Nat.}, {\bf 148} (1996), 255-274]. We choose the fecundity function to be the Beverton-Holt type function. We extend the theory of traveling waves in the population genetics model of Weinberger in [{\it SIAM J. Math. Anal.}, {\bf 13} (1982), 353-396] to the case when migration depends on age groups and a fraction of the population does not migrate.

math.DS↗

arXiv2010

Traveling wave dispersal in partially sedentary age-structured biological populations

math.DS↗

arXiv2009

Equilibrium Blocking Model of Isometric Tension

Calcium activation of striated muscle is known to exhibit a strongly cooperative dependency on calcium. Because the calcium receptor protein, troponin (Tn) is known to bind calcium non-cooperatively and has yet to be linked to a cooperative change in the myosin-blocking protein, tropomyosin (Tm), we describe a model in which cooperativity is exclusively a myosin-dependent mechanism. The model couples the energies of three well-described reactions with actin, namely, actin-Tn, actin-Tm, and actin-Tm-myosin, to the well-documented positions of Tm, B (blocking), C (central), and M (myosin-dependent) respectively. Results of simulations with and without data are consistent with a strand of Tm composed of ~20 subunits being moved by the concerted action of 3-5 myosin heads resulting in an all-or-none activation of the entire region of the thin filament overlapped by myosin. Equations derived from the model fit both equilibrium myosin binding data and steady-state calcium-dependent tension data and simulate non-cooperative calcium binding both in the presence and absence of myosin. All parameters of the model can be determined experimentally. The mechanism is consistent with steric blocking being both necessary and sufficient for regulation of striated muscle and can be applied to any actin-based contractile system that includes Tm and filamentous myosin.

q-bio.BM↗

arXiv2009

A Spectral Theory of Non-Uniformly Continuous Functions and the Loomis-Arendt-Batty-Vu Theory on the Asymptotic Behavior of Solutions of Evolution Equations

In this paper we present a new approach to the spectral theory of {\it non-uniformly continuous} functions and a new framework for the Loomis-Arendt-Batty-Vu theory. Our approach is direct and free of $C_0$-semigroups, so the obtained results, that extend previous ones, can be applied to large classes of evolution equations and their solutions.

math.FA↗

arXiv2009

Circular spectrum and bounded solutions of periodic evolution equations

We consider the existence and uniqueness of bounded solutions of periodic evolution equations of the form $u'=A(t)u+εH(t,u)+f(t)$, where $A(t)$ is, in general, an unbounded operator depending 1-periodically on $t$, $H$ is 1-periodic in $t$, $ε$ is small, and $f$ is a bounded and continuous function that is not necessarily uniformly continuous. We propose a new approach to the spectral theory of functions via the concept of "circular spectrum" and then apply it to study the linear equations $u'=A(t)u+f(t)$ with general conditions on $f$. For small $ε$ we show that the perturbed equation inherits some properties of the linear unperturbed one. The main results extend recent results in the direction, saying that if the unitary spectrum of the monodromy operator does not intersect the circular spectrum of $f$, then the evolution equation has a unique mild solution with its circular spectrum contained in the circular spectrum of $f$.

math.DS↗

arXiv2008

Asymptotic Behavior of Individual Orbits of Discrete Systems

We consider the asymptotic behavior of bounded solutions of the difference equations of the form $x(n+1)=Bx(n) + y(n)$ in a Banach space $\X$, where $n=1,2,...$, $B$ is a linear continuous operator in $\X$, and $(y(n))$ is a sequence in $\X$ converging to 0 as $n\to\infty$. An obtained result with an elementary proof says that if $σ(B) \cap \{|z|=1\} \subset \{1\}$, then every bounded solution $x(n)$ has the property that $\lim_{n\to\infty} (x(n+1)-x(n)) =0$. This result extends a theorem due to Katznelson-Tzafriri. Moreover, the techniques of the proof are furthered to study the individual stability of solutions of the discrete system. A discussion on further extensions is also given.

math.DS↗

arXiv2008

Perron Theorem in the Monotone Iteration Method for Traveling Waves in Delayed Reaction-Diffusion Equations

In this paper we revisit the existence of traveling waves for delayed reaction diffusion equations by the monotone iteration method. We show that Perron Theorem on existence of bounded solution provides a rigorous and constructive framework to find traveling wave solutions of reaction diffusion systems with time delay. The method is tried out on two classical examples with delay: the predator-prey and Belousov-Zhabotinskii models.

math.DS↗

arXiv2007

Massera Type Theorem for Abstract Functional Differential Equations

The paper is concerned with conditions for the existence of almost periodic solutions of the following abstract functional differential equation $ \dot u(t) = Au(t) + [{\cal B}u](t) +f(t), $ where $A$ is a closed operator in a Banach space $\X$, $\cal B$ is a general bounded linear operator in the function space of all $\X$-valued bounded and uniformly continuous functions that satisfies a so-called {\it autonomous} condition. We develop a general procedure to carry out the decomposition that does not need the well-posedness of the equations. The obtained conditions are of Massera type, which are stated in terms of spectral conditions of the operator ${\cal A}+{\cal B}$ and the spectrum of $f$. Moreover, we give conditions for the equation not to have quasi-periodic solutions with different structures of spectrum. The obtained results extend previous ones.

math.FA↗

arXiv2007

Katznelson-Tzafriri Type Theorems for Individual Solutions of Evolution Equations

In this paper we present an extension of the Katznelson-Tzafriri Theorem to the asymptotic behavior of individual solutions of evolution equations $u'(t) =Au(t)+f(t)$. The obtained results do not require the uniform continuity of solutions as well as the well-posedness of the equations. The method of study is based on a recently developed approach to the spectral of functions that is direct and free of C_0-semigroups.

math.DS↗