let r be an associative ring with identity, c(r) be the category of com-plexes of r-modules and flat(c(r)) be the class of all at complexes of r-modules. we show that the at cotorsion theory (flat(c(r)); flat(c(r))−)have enough injectives in c(r). as an application, we prove that for each atcomplex f and each complex y of r-modules, exti (f,x)= 0, whenever ris n-perfect and i > n.

Let $R$ be a commutative Noetherian ring with non-zero identity and $fa$ an ideal of $R$. Let $M$ be a finite $R$--module of finite projective dimension and $N$ an arbitrary finite $R$--module. We characterize the membership of the generalized local cohomology modules $lc^{i}_{fa}(M,N)$ in certain Serre subcategories of the category of modules from upper bounds. We define and study the properti...

inspired by a recent work of buchweitz and flenner, we show that, for a semidualizing bimodule $c$, $c$--perfect complexes have the ability to detect when a ring is strongly regular.it is shown that there exists a class of modules which admit minimal resolutions of $c$--projective modules.

statement of problem: failure of endodontic treatment is determined on the basis of radiographic findings and clinical signs and/ or symptoms of the treated teeth. purpose: the purpose of this study was to determine endodontic treatment failure in relation to various factors influencing it in teeth with periapical lesions (clinically and radiographically). materials and methods: teeth which had...

in this errata, we reconsider and modify two propositions and their corollaries which were written on epi-retractable and co-epi-retractable modules.

In this paper, we introduce the dual notion of strongly top modules and study some of the basic properties of this class of modules.

The configuration management of a sensor network composed of tens or up to thousands of nodes is difficult due to the limit of memory space and energy consumption. This paper presents an approach for dynamic reconfiguration of application modules in sensor networks based on Nano-Qplus. The version information from proposed methods is registered into NVSync (Nano-Qplus Version Synchronization), ...

We define the notion of almost $n$-layered $QTAG$-modules and study their basic properties. One of the main result is that almost 1-layered modules are almost $(omega+1)$-projective exactly when they are almost direct sum of countably generated modules of length less than or equal to $(omega+1)$. Some other characterizations of this new class are also established.