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In this paper we propose a new formal operation on words and languages, called superposition. By this operation, based on a Watson–Crick-like complementarity, we can generate a set of words, starting from a pair of words, in which the contribution of a word to the result need not be one subword only, as happens in classical bio-operations of DNA computing.(More)
Marine bacteria exposed to antibiotics in fish farms can acquire antimicrobial resistance by mobile genetic elements and horizontal gene transfer. A total of 872 autochthonous marine bacterial strains was isolated from samples collected from four different fish farms located at northern and southern Italian Adriatic Sea. Resistance to only tetracycline(More)
AIMS The aim of this study was to analyse the intraspecific variability of Photobacterium damselae ssp. damselae strains isolated from different cultured marine fish species using molecular typing methods. METHODS AND RESULTS Twenty P. damselae ssp. damselae strains isolated from marine fish species were used in this study. Phenotypic characterization of(More)
Redbanded seabream, Pagrus auriga Valenciennes (Sparidae), has a wide geographical distribution and a very important commercial value in European countries. Recently, this species has been successfully cultured in the C.) as a result of extensive studies on its reproductive cycle, nutrition and growth (Prieto, Cañavate & Cardenas 2003). However, as a(More)
We prove the following completeness theorem: If the fixed point operation over a category is defined by initial@, then the equations satisfied by the fixed point operation are exactly those of iteration theories. Thus, in such categories, the equational axioms of iteration theories provide a sound and complete axiomatization of the equational properties of(More)
A membrane system (P system) is a model of computation inspired by some basic features of the structure and behaviour of living cells. In this paper we consider systems with string-objects processed by rewriting, with the communication controlled by conditions on the contents of the strings. Symbols, substrings (in an arbitrary place, or as a(More)
We provide a finite equational axiomatization for bisimulation equivalence of nondeterministic interpretation of regular expressions. Our axiomatization is heavily based on the one by Salomaa, that provided an implicative axiomatization for a large subset of regular expressions, namely all those that satisfy the non-empty word property (i.e. without 1(More)
Nondeterminism is a direct outcome of interactions and is, therefore a central ingredient for modelling concurrent systems. Trees are very useful for modelling nondeterministic behaviour. We aim at a tree-based interpretation of regular expressions and study the effect of removing the idempotence law X+X=X and the distribution law X v (Y+Z)=X vY+X vZ from(More)
The logical characterization of the strong and the weak (ignoring silent actions) versions of resource bisimulation are studied. The temporal logics we introduce are variants of Hennessy-Milner Logics that use graded modalities instead of the classical box and diamond operators. The considered strong bisimulation induces an equivalence that, when applied to(More)