A simple matrix is a (0,1)-matrix with no repeated columns. For a (0,1)-matrix F , we define that a (0,1)-matrix A has F as a configuration if there is a submatrix of A which is a row and column permutation of F (trace is the set system version of a configuration). Let |A| denote the number of columns of A. We define forb(m,F ) = max{|A| : A is m-rowed simple matrix and has no configuration F}....

Combinations of chemical and genetic approaches were used to study the function of divalent metal ions in cleavage of RNA by the ribozyme RNase P RNA. We show that different divalent metal ions have differential effects on cleavage site recognition and rescue of cleavage activity by mixing divalent metal ions that do not promote cleavage by themselves. We conclude that efficient and correct cle...

[This corrects the article DOI: 10.1371/journal.pone.0161913.].

the hotelling's  control chart, is the most widely used multivariate procedure for monitoring  two or more related quality characteristics, but it’s power lacks the desired performance in detecting small to moderate shifts. recently, the variable sampling intervals (vsi) control scheme in which the length of successive sampling intervals is determined upon the preceding values has been pro...

Introduction: We investigate the behavior of the MR magnetization vector during RF pulses in the presence of rapid transverse relaxation. The transverse relaxation is divided into two separate mechanisms: Homogeneously broadened lines which resulting in irreversible T2 amplitude decay, and inhomogeneously broadened lines resulting in dephasing and in principle refocusable T2’. While the two dif...