Simultaneous Replacement in Normal Programs

The simultaneous replacement transformation operation is here defined and studied w.r.t. normal programs. We give applicability conditions able to ensure the correctness of the operation w.r.t. the set of logical consequences of the completed database. We consider separately the cases in which the underlying language is infinite and finite; in this latter case we also distinguish according to the kind of domain closure axioms adopted. As corollaries we obtain results for Fitting's and Kunen's semantics. We also show how simultaneous replacement can mimic other transformation operations such as thinning, fattening and folding, thus producing applicability conditions for them too

Transforming Normal Programs by Replacement

The replacement transformation operation, already defined in [28], is studied wrt normal programs. We give applicability conditions able to ensure the correctness of the operation wrt Fitting's and Kunen's semantics. We show how replacement can mimic other transformation operations such as thinning, fattening and folding, thus producing applicability conditions for them too. Furthermore we characterize a transformation sequence for which the preservation of Fitting's and Kunen's semantics is ensured

Comparison of Metabolic Pathways by Considering Potential Fluxes

Comparison of metabolic pathways is useful in phylogenetic analysis and for understanding metabolic functions when studying diseases and in drugs engineering. In the literature many techniques have been proposed to compare metabolic pathways, but most of them focus on structural aspects, while behavioural or functional aspects are generally not considered. In this paper we propose a new method for comparing metabolic pathways of different organisms based on a similarity measure which considers both homology of reactions and functional aspects of the pathways. The latter are captured by relying on a Petri net representation of the pathways and comparing the corresponding T-invariant bases, which represent potential fluxes in the nets. The approach is implemented in a prototype tool, CoMeta, which allows us to test and validate our proposal. Some experiments with CoMeta are presented

Petri nets for modelling and analysing trophic networks

We consider trophic networks, a kind of networks used in ecology to represent feeding interactions (what-eats-what) in an ecosys- tem. We observe that trophic networks can be naturally modelled as Petri nets and this suggests the possibility of exploiting Petri nets for the analysis and simulation of trophic networks. Some preliminary steps in this directions and some ideas for future development are presented

Autoimmunity in gestational diabetes mellitus in Sardinia: a preliminary case-control report

<p>Abstract</p> <p>Background</p> <p>We previously reported a high prevalence (22.3%) of gestational diabetes mellitus (GDM) in a large group of Sardinian women, in contrast with the prevalence of Type 2 diabetes. Sardinia has an unusual distribution of haplotypes and genotypes, with the highest population frequency of HLA DR3 in the world, and after Finland, the highest prevalence of Type 1 diabetes and Autoimmune-related Diseases. In this study we preliminarily tested the prevalence of serological markers of Type 1 diabetes in a group of Sardinian GDM patients.</p> <p>Methods</p> <p>We determined glutamic decarboxylase antibodies (anti-GAD65), protein tyrosine phosphatase ICA 512 (IA2) antibodies (anti-IA2), and IAA in 62 GDM patients, and in 56 controls with matching age, gestational age and parity.</p> <p>Results</p> <p>We found a high prevalence and very unusual distribution of antibodies in GDM patients (38.8%), the anti-IA2 being the most frequent antibody. Out of all our GDM patients, 38.8% (24 of 62) were positive for at least one antibody. Anti-IA2 was present in 29.0 % (18 out of 62) vs. 7.1% (4 out of 56) in the controls (P < 0.001). IAA was present in 14.5% (9 out of 62) of our GDM patients, and absent in the control subjects (P < 0.001). Anti-GAD65 was also present in GDM patients, with a prevalence of 3.2% (2 out of 62) while it was absent in the control group (P = NS). Pre-gestational weight was significantly lower (57.78 ± 9.8 vs 65.9 ± 17.3 <it>P </it>= 0.04) in auto-antibodies- positive GDM patients.</p> <p>Conclusion</p> <p>These results are in contrast with the very low prevalence of all antibodies reported in Italy. If confirmed, they could indicate that a large proportion of GDM patients in Sardinia have an autoimmune origin, in accordance with the high prevalence of Type 1 diabetes.</p

Petri nets for modelling metabolic pathways: a survey

In the last 15 years, several research efforts have been directed towards the representation and the analysis of metabolic pathways by using Petri nets. The goal of this paper is twofold. First, we discuss how the knowledge about metabolic pathways can be represented with Petri nets. We point out the main problems that arise in the construction of a Petri net model of a metabolic pathway and we outline some solutions proposed in the literature. Second, we present a comprehensive review of recent research on this topic, in order to assess the maturity of the field and the availability of a methodology for modelling a metabolic pathway by a corresponding Petri net

A valuable experience in Computational Logic

In this paper, we briefly describe our esperience in the field of verification and transformation of logic programming. Though now we are working in a completely different field, verification of security properties on one hand and biosystems analysis on the other, our previous experience continues to be a valuable guide