a module m is called epi-retractable if every submodule of m is a homomorphic image of m. dually, a module m is called co-epi-retractable if it contains a copy of each of its factor modules. in special case, a ring r is called co-pli (resp. co-pri) if rr (resp. rr) is co-epi-retractable. it is proved that if r is a left principal right duo ring, then every left ideal of r is an epi-retractable ...

Recently, we released two LAPACK subroutines that implement Aasen’s algorithms for solving a symmetric indefinite linear system of equations. The first implementation is based on a partitioned right-looking variant of Aasen’s algorithm (the column-wise left-looking panel factorization, followed by the right-looking trailing submatrix update using the panel). The second implements the two-stage ...

We theoretically investigate resonant tunneling through S- and U-shaped nanostructured graphene nanoribbons. A rich structure of resonant tunneling peaks is found emanating from different quasi-bound states in the middle region. The tunneling current can be turned on and off by varying the Fermi energy. Tunability of resonant tunneling is realized by changing the width of the left and/or right ...

Some novel quasi-planar chiral inclusions, feasible from standard photo-etching techniques, are proposed. It is shown that such inclusions can be designed in order to present balanced electric, magnetic and magneto-electric polarizabilities. Using these inclusions, random and periodic bi-isotropic artificial metamaterials exhibiting a balanced positive/negative refractive index can be build up....

background: one of the important etiologies for cryptogenic stroke is paradoxical embolization secondary to patent foramen ovale (pfo). foramen ovale can secondarily reopen due to pulmonary arterial hypertension (pah) which is common among the older age. pah is known as a frequent and life threatening complication of copd. the aim of this study was to determine the prevalence of pfo between cop...

Given a left module U and a right modules V over an algebra D and a bilinear form β : U × V → D, we may define an associative algebra structure on the tensor product V ⊗D U . This algebra is called a near-matrix algebra. In this paper, we shall investigate algebras filtered by near-matrix algebras in some nice way and give a unified treatment for quasi-hereditary algebras, cellular algebras, an...

Abstract We study the large time asymptotics of solutions to Cauchy problem for fractional modified Korteweg-de Vries equation $$\begin{aligned} \left\{ \begin{array}{l} \partial _{t}w+\frac{1}{\alpha }\left| _{x}\right| ^{\alpha -1}\partial _{x}w=\partial _{x}\left( w^{3}\right) ,\text { }t>0,\, x\in {\mathbb {R}}\textbf{,}\\ w\left( 0,x\right) =w_{0}\left( x\right) ,\,x\in {R}} \textbf{,} ...

the concept of right (left) quotient (or residual) of an ideal η by anideal ν of an l-subring μ of a ring r is introduced. the right (left) quotients areshown to be ideals of μ . it is proved that the right quotient [η :r ν ] of an idealη by an ideal ν of an l-subring μ is the largest ideal of μ such that[η :r ν ]ν ⊆ η . most of the results pertaining to the notion of quotients(or residual) of ...