The paper presents the results of a comparative analysis ultrastructure tooth enamel (incisors, premolars and molars) in representatives morphologically (and possibly phylogenetically) similar forms small horses. These are both extinct tarpan – Equus gmelini from various sites early Holocene Ukraine (Myrne, Kamiana Mohyla Hirzhevo) modern konik polski E. przewalskii, European wild ass hydruntin...

This paper describes the foraminiferal associations along with presentation of three new agglutinated conical species to construction biozonation framework in Mahallat region central Iran. The stratigraphic distribution benthic foraminifers is used characterize assemblage zones that are ascending order: rotaliids-valvulinids Assemblage Zone, alveolinids-coskinolinids and nummulitids-discocyclin...

Let R be a commutative ring. An R-module M is called co-multiplication provided that foreach submodule N of M there exists an ideal I of R such that N = (0 : I). In this paper weshow that co-multiplication modules are a generalization of strongly duo modules. Uniserialmodules of finite length and hence valuation Artinian rings are some distinguished classes ofco-multiplication rings. In additio...

Given a sequence d→=(d1,…,dk) of natural numbers, we consider the Lie subalgebra h gl(d,F), where d=d1+⋯+dk and F is field characteristic 0, generated by two block upper triangular matrices D E partitioned according to d→, study problem computing nilpotency degree m nilradical n h. We obtain complete answer when belong certain family that arises naturally attempting classify indecomposable modu...

Benthic foraminifera are significant indicators of habitat changes and useful for paleoenvironmental reconstruction. During the Permian period, variation in species, individual sizes, morphological characteristics different assemblages, such as fusulinids, is a clue to paleoecological interpretations. The eastern part Sichuan Basin, located near equator middle Permian, Guadalupian was precipita...

Cirrate octopods are considered to resemble the ancestor of all octopuses. Cirrates inhabit deep ocean and characterized by presence fins, a cartilaginous inner shell single row suckers alternating with pairs cirri thus comprising uniserial biserial cirri. The objective this contribution is improve taxonomy Opisthoteuthis bruuni from southeastern Pacific Ocean suggest new hypothesis cirrate phy...

We give an example of a direct summand of a serial module that does not admit an indecomposable decomposition.