background: study of vascular and its secretory profile changes is an important issue in pathogenesis of radiation myelopathy. this paper reports the prostacyclin concentration changes after low-moderate doses of x-irradiation within a short period of time. materials and methods: cervical cords of wistar rats were irradiated to doses of 0.5, 1, 2, 4 and 6 gy x-rays. after 24 hours, 2 and 13 wee...

for a finite group $g$‎, ‎let $cent(g)$ denote the set of centralizers of single elements of $g$‎. ‎in this note we prove that if $|g|leq frac{3}{2}|cent(g)|$ and $g$ is 2-nilpotent‎, ‎then $gcong s_3‎, ‎d_{10}$ or $s_3times s_3$‎. ‎this result gives a partial and positive answer to a conjecture raised by a‎. ‎r‎. ‎ashrafi [on finite groups with a given number of centralizers‎, ‎algebra‎ ‎collo...