In Salmonella typhimurium, expression of the hisR locus, a tRNA operon, decreases upon inhibiting DNA gyrase. Here, the hisR promoter dependence on negative DNA supercoiling was examined in vivo and in vitro. Mutant analysis showed the sequence determinants of this dependence to lie in the region between the -10 box and the transcription start site. As with most promoters subject to stringent c...

let $d=(v,a)$ be a finite simple directed graph. a function$f:vlongrightarrow {-1,0,1}$ is called a twin minus dominatingfunction (tmdf) if $f(n^-[v])ge 1$ and $f(n^+[v])ge 1$ for eachvertex $vin v$. the twin minus domination number of $d$ is$gamma_{-}^*(d)=min{w(f)mid f mbox{ is a tmdf of } d}$. inthis paper, we initiate the study of twin minus domination numbersin digraphs and present some lo...

The nature of the inhibition of Ehrlich tumor cell ribonucleotide reducÃ-ase by combinations of agents directed at the nonheme iron-containing component and the effector-binding com ponent was studied with the use of isobolograms. From these studies, it was determined that the combinations of pyrazoloimidazole (IMPY) and dialdehyde of inosine, IMPY and deoxyguanosine triphosphate (dGTP), IMPY a...

Introduction. This is quasi experimental research in order to determine and compare the learning level of nursing skills ( in B.A students) with self-directed learning and tutor-directed learning pattern in Shaheed Beheshti Univeristy of Medical Sciences and Health Services, Nursing and Midwifery faculty, 1998-1999. Methods. First of all, a questionnaire composed of some demographic data such ...

The nature of the inhibition of Ehrlich tumor cell ribonucleotide reductase by combinations of agents directed at the non-heme iron-containing component and the effector-binding component was studied with the use of isobolograms. From these studies, it was determined that the combinations of pyrazoloimidazole (IMPY) and dialdehyde of inosine, IMPY and deoxyguanosine triphosphate (dGTP), IMPY an...

in this paper, the definition of meet-continuity on $l$-directedcomplete posets (for short, $l$-dcpos) is introduced. as ageneralization of meet-continuity on crisp dcpos, meet-continuity on$l$-dcpos, based on the generalized scott topology, ischaracterized. in particular, it is shown that every continuous$l$-dcpo is meet-continuous and $l$-continuous retracts ofmeet-continuous $l$-dcpos are al...