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M. Ghasemi

Publications and source records attributed to M. Ghasemi.

4 recordsLinked to original sources

Jordan derivations on the $θ-$Lau products of Banach algebras

In this paper, we study Jordan derivation-like maps on the $θ-$Lau products of algebras. We characterize them and prove that under certain condition any Jordan derivation-like maps on the $θ-$Lau products is a derivation-like map. Moreover, we investigate the concept of centralizing for Jordan derivation-like maps on the $θ-$Lau products of algebras.

math.FA

Moment problem for symmetric algebras of locally convex spaces

It is explained how a locally convex (lc) topology $τ$ on a real vector space $V$ extends to a locally multiplicatively convex (lmc) topology $\overlineτ$ on the symmetric algebra $S(V)$. This allows the application of the results on lmc topological algebras obtained by Ghasemi, Kuhlmann and Marshall to obtain representations of $\overlineτ$-continuous linear functionals $L: S(V)\rightarrow \mathbb{R}$ satisfying $L(\sum S(V)^{2d}) \subseteq [0,\infty)$ (more generally, $L(M) \subseteq [0,\infty)$ for some $2d$-power module $M$ of $S(V)$) as integrals with respect to uniquely determined Radon measures $μ$ supported by special sorts of closed balls in the dual space of $V$. The result is simultaneously more general and less general than the corresponding result of Berezansky, Kondratiev and \v Sifrin. It is more general because $V$ can be any lc topological space (not just a separable nuclear space), the result holds for arbitrary $2d$-powers (not just squares), and no assumptions of quasi-analyticity are required. It is less general because it is necessary to assume that $L : S(V) \rightarrow \mathbb{R}$ is $\overlineτ$-continuous (not just continuous on each homogeneous part of $S(V)$).

math.FA

Time adaptive numerical solution of a highly degenerate diffusion-reaction biofilm model based on regularisation

We consider a quasilinear degenerate diffusion-reaction system that describes biofilm formation. The model exhibits two non-linear effects: a power law degeneracy as one of the dependent variables vanishes and a super diffusion singularity as it approaches unity. Biologically relevant solutions are characterized by a moving interface and gradient blow-up there. Discretisation of the PDE in space by a standard Finite Volume scheme leads to a singular system of ordinary differential equations. We show that regularisation of this system allows the application of error controlled adaptive integration techniques to solve the underlying PDE. This overcomes the major limitation of existing methods for this type of problem which work with fixed time-steps. We apply the resulting numerical method to study the effect of signal diffusion in the aqueous phase on quorum sensing induction in a biofilm colony.

math.NA