Sleptsov Nets are Turing-complete

The present paper proves that a Sleptsov net (SN) is Turing-complete, that considerably improves, with a brief construct, the previous result that a strong SN is Turing-complete. Remind that, unlike Petri nets, an SN always fires enabled transitions at their maximal firing multiplicity, as a single step, leaving for a nondeterministic choice of which fireable transitions to fire. A strong SN restricts nondeterministic choice to firing only the transitions having the highest firing multiplicity.Comment: Sleptsov Net Computing Resolves Modern Supercomputing Problems, https://technews.acm.org/archives.cfm?fo=2023-04-apr/apr-21-2023.htm

Ladder Metamodeling & PLC Program Validation through Time Petri Nets

International audienceLadder Diagram (LD) is the most used programming language for Programmable Logical Controllers (PLCs). A PLC is a special purpose industrial computer used to automate industrial processes. Bugs in LD programs are very costly and sometimes are even a threat to human safety. We propose a model driven approach for formal verification of LD programs through model-checking. We provide a metamodel for a subset of the LD language. We define a time Petri net (TPN) semantics for LD programs through an ATL model transformation. Finally, we automatically generate behavioral properties over the LD models as LTL formulae which are then checked over the generated TPN using the model-checkers available in the Tina toolkit. We focus on race condition detection. This work is supported by the topcased project, part of the french cluster Aerospace Valley (granted by the french DGE), cf. http://www.topcased.or

Langage intermédiaire et transformations de modèles pour le développement de systèmes temps-réel : retour d'expérience sur la chaîne de vérification formelle Fiacre

6 pagesInternational audienceWe discuss the results obtained during the development of a formal verification toolchain for AADL based on a model driven engineering approach. Our approach is characterized by the use of the pivot language FIACRE to facilitate verification activities and transformations between models. We quickly analyse the first return on experience and present ongoing work started in the scope of the Quarteft project to improve the verification chain.Nous présentons les résultats obtenus durant le développement d’une chaîne de vérifi-cation formelle pour le langage d’architecture AADL basé sur une approche ingénierie dirigéepar les modèles. Notre approche se caractérise par l’utilisation du langage pivot FIACRE pourfaciliter les activités de vérification et de transformations entre modèles. Nous commentonsles premiers retours d’expérience issus de la mise en oeuvre de cette chaîne de vérification etprésentons en conclusion les travaux en cours dans le cadre du projet Quarteft qui visent àl’améliore

Fiacre: an Intermediate Language for Model Verification in the Topcased Environment

International audienceFiacre was designed in the framework of the TOPCASED project dealing with model-driven engineering and gathering numerous partners, from both industry and academics. Therefore, Fiacre is designed both as the target language of model transformation engines from various models such as SDL, UML, AADL, and as the source language of compilers into the targeted verification toolboxes, namely CADP and Tina in the first step. In this paper, we present the Fiacre language. Then transformations from AADL to Fiacre are illustrated on a small example

Formal Verification of AADL models with Fiacre and Tina

9 pagesInternational audienceThis paper details works undertaken in the scope of the Spices project concerning the behavioral verification of AADL models. We give a high-level view of the tools involved and describe the successive transformations performed by our verification process. We also report on an experiment carried out in order to evaluate our framework and give the first experimental results obtained on real-size models. This demonstrator models a network protocol in charge of data communications between an airplane and ground stations. From this study we draw a set of conclusions about the integration of model-checking tools in an industrial development process

Forty Years of Erratic Insecticide Resistance Evolution in the Mosquito Culex pipiens

One view of adaptation is that it proceeds by the slow and steady accumulation of beneficial mutations with small effects. It is difficult to test this model, since in most cases the genetic basis of adaptation can only be studied a posteriori with traits that have evolved for a long period of time through an unknown sequence of steps. In this paper, we show how ace-1, a gene involved in resistance to organophosphorous insecticide in the mosquito Culex pipiens, has evolved during 40 years of an insecticide control program. Initially, a major resistance allele with strong deleterious side effects spread through the population. Later, a duplication combining a susceptible and a resistance ace-1 allele began to spread but did not replace the original resistance allele, as it is sublethal when homozygous. Last, a second duplication, (also sublethal when homozygous) began to spread because heterozygotes for the two duplications do not exhibit deleterious pleiotropic effects. Double overdominance now maintains these four alleles across treated and nontreated areas. Thus, ace-1 evolution does not proceed via the steady accumulation of beneficial mutations. Instead, resistance evolution has been an erratic combination of mutation, positive selection, and the rearrangement of existing variation leading to complex genetic architecture

Theoretical evidence of the observed kinetic order dependence on temperature during the N2O decomposition over Fe-ZSM-5

The characterization of Fe/ZSM5 zeolite materials, the nature of Fe-sites active in N2O direct decomposition, as well as the rate limiting step are still a matter of debate. The mechanism of N2O decomposition on the binuclear oxo-hydroxo bridged extraframework iron core site [FeII(m-O)(m-OH)FeII]+ inside the ZSM-5 zeolite has been studied by combining theoretical and experimental approaches. The overall calculated path of N2O decomposition involves the oxidation of binuclear FeII core sites by N2O (atomic a-oxygen formation) and the recombination of two surface a-oxygen atoms leading to the formation of molecular oxygen. Rate parameters computed using standard statistical mechanics and transition state theory reveal that elementary catalytic steps involved into N2O decomposition are strongly dependent on the temperature. This theoretical result was compared to the experimentally observed steady state kinetics of the N2O decomposition and temperature-programmed desorption (TPD) experiments. A switch of the reaction order with respect to N2O pressure from zero to one occurs at around 800 K suggesting a change of the rate determining step from the a-oxygen recombination to a-oxygen formation. The TPD results on the molecular oxygen desorption confirmed the mechanism proposed

Overview of the current use of levosimendan in France: a prospective observational cohort study

Abstract Background Following the results of randomized controlled trials on levosimendan, French health authorities requested an update of the current use and side-effects of this medication on a national scale. Method The France-LEVO registry was a prospective observational cohort study reflecting the indications, dosing regimens, and side-effects of levosimendan, as well as patient outcomes over a year. Results The patients included ( n = 602) represented 29.6% of the national yearly use of levosimendan in France. They were treated for cardiogenic shock ( n = 250, 41.5%), decompensated heart failure ( n = 127, 21.1%), cardiac surgery-related low cardiac output prophylaxis and/or treatment ( n = 86, 14.3%), and weaning from veno-arterial extracorporeal membrane oxygenation ( n = 82, 13.6%). They received 0.18 ± 0.07 µg/kg/min levosimendan over 26 ± 8 h. An initial bolus was administered in 45 patients (7.5%), 103 (17.1%) received repeated infusions, and 461 (76.6%) received inotropes and or vasoactive agents concomitantly. Hypotension was reported in 218 patients (36.2%), atrial fibrillation in 85 (14.1%), and serious adverse events in 17 (2.8%). 136 patients (22.6%) died in hospital, and 26 (4.3%) during the 90-day follow-up. Conclusions We observed that levosimendan was used in accordance with recent recommendations by French physicians. Hypotension and atrial fibrillation remained the most frequent side-effects, while serious adverse event potentially attributable to levosimendan were infrequent. The results suggest that this medication was safe and potentially associated with some benefit in the population studied