the aim of this paper is to study the $(alpha‎, ‎gamma)$-prolongation of central extensions‎. ‎we obtain the obstruction theory for $(alpha‎, ‎gamma)$-prolongations and classify $(alpha‎, ‎gamma)$-prolongations thanks to low-dimensional cohomology groups of groups‎.

It is very likely that in 3-4 years the construction of one or two linear colliders with c.m.s energy up to 0.5–1.5 TeV will be started. Besides eecollisions, linear colliders give a unique possibility to study γγ and γe interactions at energies and luminosities comparable to those in ee collisions. High energy photons for γγ and γe collisions can be obtained using laser backscattering. These t...

 Let $R$ be an associative ring with identity and $Z^*(R)$ be its set of non-zero zero divisors.  The zero-divisor graph of $R$, denoted by $Gamma(R)$, is the graph whose vertices are the non-zero  zero-divisors of  $R$, and two distinct vertices $r$ and $s$ are adjacent if and only if $rs=0$ or $sr=0$.  In this paper, we bring some results about undirected zero-divisor graph of a monoid ring o...

high spin states in the neutron rich nucleus 191os has been populated for the first time using the82se+192os deep-inelastic reaction at 460 mev beam energy using the alpi accelerators at the laboratorynazionali di legnaro, italy. high fold γ-γ coincidences were acquired with the 4π spectrometer gaspdetector array, consisting of 40 compton-suppressed, large-volume germanium detectors with an inn...

natural radionuclides present in soil as well as certain anthropogenic radionuclides released to the environment are the major contributors to terrestrial outdoor exposures. in the assessment of human exposures from environmental radioactivity, besides the conventional method of soil and vegetation sampling combined with laboratory based analyses of environmental media, the other choice would b...

introduction foodstuffs are known to contain natural and artificial radionuclides. determination of radionuclide concentration is of great significance for the protection of human health. the main objective of the present study was the quantification of radionuclides in tea samples, cultivated in guilan province in north of iran. materials and methods the activity concentrations of 226ra, 232th...

Let $R$ be a ring (not necessarily commutative) with nonzero identity. We define $Gamma(R)$ to be the graph with vertex set $R$ in which two distinct vertices $x$ and $y$ are adjacent if and only if there exist unit elements $u,v$ of $R$ such that $x+uyv$ is a unit of $R$. In this paper, basic properties of $Gamma(R)$ are studied. We investigate connectivity and the girth of $Gamma(R)$, where $...