In this paper, we study some ring theoretic properties of the amalgamated duplication ring $Rbowtie I$ of a commutative Noetherian ring $R$ along an ideal $I$ of $R$ which was introduced by D'Anna and Fontana. Indeed, it is determined that when $Rbowtie I$ satisfies Serre's conditions $(R_n)$ and $(S_n)$, and when is a normal ring, a generalized Cohen-Macaulay ring and finally a filter ring.

Air pollution emissions were not continually monitored in the Upper Silesian Industrial District (USID), southern Poland, and data is only available for the last 20 years. Long-lasting and severe tree ring reductions in pines growing 5-20 km north of the USID area recorded particularly high levels of air pollution emissions in the period 1950-1990. Especially high amounts of reductions and many...

The fidelity of inferences on volcanic cooling from tree-ring density records has recently come into question, with competing claims that temperature reconstructions based on tree-ring records underestimate cooling due to an increased likelihood of missing rings or overestimate cooling due to reduced light availability accentuating the response. Here we test these competing hypotheses in the la...

Cohn called a ring $R$ is reversible if whenever $ab = 0,$ then $ba = 0$ for $a,bin R.$ The reversible property is an important role in noncommutative ring theory‎. ‎Recently‎, ‎Abdul-Jabbar et al‎. ‎studied the reversible ring property on nilpotent elements‎, ‎introducing‎ the concept of commutativity of nilpotent elements at zero (simply‎, ‎a CNZ ring)‎. ‎In this paper‎, ‎we extend the CNZ pr...

For a ring endomorphism $alpha$ and an $alpha$-derivation $delta$, we introduce a concept, so called skew $pi$-Armendariz ring, that is a generalization of both $pi$-Armendariz rings, and $(alpha,delta)$-compatible skew Armendariz rings. We first observe the basic properties of skew $pi$-Armendariz rings, and extend the class of skew $pi$-Armendariz rings through various ring extensions. We nex...

background: diagnostic models are frequently used to assess the role of risk factors on disease complications, and therefore to avoid them. missing data is an issue that challenges the model making. the aim of this study was to develop a diagnostic model to predict death in hiv/ aids patients when missing data exist. methods: hiv patients (n=1460) referred to voluntary consoling and testing cen...

a twenty-year-old girl was referred with tracheal stenosis (ts) which was a consequence of prolonged intubation after head injury because of previous car accident. the patient was aphasic and had normal respiration. fiberoptic bronchoscopy showed complete tracheal obstruction at second tracheal ring level. distal trachea was normal through tracheostomy tube. removal of the tracheostomy tube and...

Let X be a del Pezzo surface of degree one over an algebraically closed field, and let Cox(X) be its total coordinate ring. We prove the missing case of a conjecture of Batyrev and Popov, which states that Cox(X) is a quadratic algebra. We use a complex of vector spaces whose homology determines part of the structure of the minimal free Pic(X)-graded resolution of Cox(X) over a polynomial ring....

Signal-event nets provide a modular modeling technique based on Petri nets. Actions of a module can be activated or can be prevented by another module through condition arcs. One-sided synchronization of modules is done by signal-events, which cause the execution of actions in steps. But due to condition arcs and signal-events simultaneous ring of steps may lead to markings, which are not reach...

Bresar in 1993 proved that each biderivation on a noncommutative prime ring is a multiple of a commutatot. A result of it is a characterization of commuting additive mappings, because each commuting additive map give rise to a biderivation. Then in 1995, he investigated biderivations, generalized biderivations and sigma-biderivations on a prime ring and generalized the results of derivations fo...