We show, mostly through detailed examples, that programming patterns known to involve the notion of virtual types can be implemented directly and concisely using parametric poly-morphism. A signiicant improvement we make over previous approaches is to allow related classes to be deened independently. This solution is more exible, more general, and we believe, simpler than other type-safe soluti...

We introduce a new concept in the area of formal logic: axioms for model morphisms. We work in the setting of specification languages that define the semantics of a theory as a category of models. While it is routine to use axioms to specify the class of models of a theory, there has so far been no analogue to systematically specify the morphisms between these models. This leads to subtle probl...

The preparation of synthetic ribonucleic acid in which one of the nucleotide species is labeled with P32, makes possible studies on the distribution of the labeled nucleotide in the polynucleotide chain. Fig. 1 presents the structure of a polynucleotide in which labeled adenylic acid is randomly distributed. Hydrolysis of such a polymer with snake venom phosphodiesterase (Fig. 1A) will yield a ...

background: single nucleotide polymorphism (snps) are considered as one of the underlying causes of male infertility. proper sperm chromatin packaging which involves replacement of histones with protamines has profound effect on male fertility. over 20 snps have been reported for the protamine 1 and 2. materials and methods: the aim of this study was to evaluate the frequency of two previously ...

Interaction of cGMP-dependent protein kinase with histones H2A, H2B, H3, and H4, or poly(L-arginine) resulted in changes in enzyme conformation such that inactivation of cGMP binding and activation of basal catalytic activity (assayed without cGMP) occurred. Total kinase activity as determined by phosphorylation of exogenous substrates subsequently decreased, but autophosphorylation of the enzy...

A sequence of 20 nucleotide residues immediately adjacent to the 3'-terminal poly(A) in Rous sarcoma virus (Prague strain, subgroup C) 35S RNA has been determined by extension of a riboguanylic acid-terminated oligothymidylic acid primer hybridized at the 5' end of the 3'-terminal poly(A) with purified reverse transcriptase (RNA-directed DNA polymerase; deoxynucleosidetriphosphate:DNA deoxynucl...