1,721,557 research outputs found
Analysis of COVID-19 Data with PRISM: Parameter Estimation and SIR Modelling
No full textWe propose a pipeline for the stochastic analysis of a SIR model for COVID-19 through the stochastic model checker PRISM. The pipeline consists in: (i) the definition of a modified SIR model, able to include governmental restriction and prevention measures through an additional time-dependent coefficient; (ii) parameter estimation based on real epidemic data; (iii) translation of the modified SIR model into a Continuous Time Markov Chain (CTMC) expressed using the PRISM input language; and (iv) stochastic analysis (simulation and model checking) with PRISM
La direttiva 2016/680/UE e la protezione dei dati personali nell’ambito della sicurezza pubblica e della giustizia penale
No full textIl contributo studia la direttiva 670/2016 sul trattamento dei dati in materia di giustizia e sicurezza, anche alla luce delle più complessive modifiche al sistema della privacy introdotte con il coevo regolamento 67
Las reformas de la administración regional en Italia
No full textIl contributo ripercorre l'evoluzione delle Regioni italiane sotto il profilo della loro struttura amministrativa e delle modalità di esercizio delle funzioni
Objective/MC: A high-level model checking language: Formalization of the imperative core and translation into PRISM
No full textAmong model checking tools, the behaviour of a system is often formalized as a transition system with atomic propositions associated with states (Kripke structure). In current modeling languages, transitions are usually specified as updates of the systemâs variables to be performed when certain conditions are satisfied. However, such a low-level representation makes the description of complex transformations difficult, in particular in the presence of structured data. We present Objective/MC, a high-level language with imperative semantics for modeling finite-state systems. The language features are selected with the aim of enabling the translation of models into compact transition systems, amenable to efficient verification via model checking. To this end, we have developed a compiler of our high-level language into the modeling language of the PRISM probabilistic model checker. One of the main characteristics of the language is that it makes a very different treatment of global and local variables. It is assumed that global variables are actually the variables that describe the state of the modeled system, whereas local variables are only used to ease the specification of the systemâs internal mechanisms. In this paper, we give a complete formal definition of the language, its type system and static analyses, of the transformations to be performed at the level of the Control Flow Graph for the pruning of local variables, and of the PRISM code generation
Formal modeling and analysis of safety-critical human multitasking
No full textWhen a person is concurrently interacting with different systems, the amount of cognitive resources required (cognitive load) could be too high and might prevent some tasks from being completed. When such human multitasking involves safety-critical tasks, such as in an airplane, a spacecraft, or a car, failure to devote sufficient attention to the different tasks could have serious consequences. For example, using a GPS with high cognitive load while driving might take the attention away for too long from the safety-critical task of driving the car. To study this problem, we define an executable formal model of human attention and multitasking in Real-Time Maude. It includes a description of the human working memory and the cognitive processes involved in the interaction with a device. Our framework enables us to analyze human multitasking through simulation, reachability analysis, and LTL and timed CTL model checking, and we show how a number of prototypical multitasking problems can be analyzed in Real-Time Maude. We illustrate our modeling and analysis framework by studying: (i) the interaction with a GPS navigation system while driving, (ii) some typical scenarios involving human errors in air traffic control (ATC), and (iii) a medical operator setting multiple infusion pumps simultaneously. We apply model checking to show that in some cases the cognitive load of the navigation system could cause the driver to keep the focus away from driving for too long, and that working memory overload and distraction may cause an air traffic controller or a medical operator to make critical mistakes
Formal characterization and efficient verification of a biological robustness property
No full textRobustness is an observable property for which a chemical reaction network (CRN) can maintain its functionalities despite the influence of different perturbations. In general, to verify whether a network is robust, it is necessary to consider all the possible parameter configurations. This is a process that can entail a massive computational effort. In the work of Rizk et al., the authors propose a definition of robustness in linear temporal logic (LTL) through which, on the basis of multiple numerical timed traces obtained by considering different parameter configurations, they verify the robustness of a reaction network. In this paper, we focus on a notion of initial concentration robustness (alpha -robustness), that is related to the influence of the perturbation of the initial concentration of one species (i.e., the input) on the concentration of another species (i.e., the output) at the steady state. We characterize this notion of robustness in the framework proposed by Rizk et al., and we show that, for monotonic reaction networks, this allows us to drastically reduce the number of traces necessary to verify robustness of the CRN
Encoding Boolean networks into reaction systems for investigating causal dependencies in gene regulation
No full textGene regulatory networks represent the interactions among genes regulating the activation of specific cell functionalities. They have been successfully modelled using Boolean networks, where a set of Boolean variables model the activation state of each gene, and Boolean functions model positive and negative influences among genes. Moreover, when the effect of such influences is additive, threshold Boolean networks, in which Boolean functions are replaced by simpler threshold functions, turned out to be particularly effective. In this paper we propose a systematic translation of threshold Boolean networks into Ehrenfeucht and Rozenberg's reaction systems. Our translation produces a non redundant set of reactions, each using a minimal set of objects. This translation allows us to simulate the behaviour of a general threshold Boolean network by simply executing the (closed) reaction system we obtain, and to investigate causality relations among genes by applying tools available for reaction systems. We implemented our translation in an open-source tool and applied it in two case studies: the gene regulation network of segment polarity in Drosophila melanogaster and the one controlling the differentiation of Th cells in the immune system. In both case studies, we investigate causalities among genes in the reaction system obtained from the translation by applying a tool for the computation of formula based predictors. In the context of the second case study, we show that also Boolean networks with non-additive influences and modelling genes with multiple expression levels can be dealt with by our approach
Analysis and Verification of Robustness Properties in Becker-Döring Model
No full textMany biochemical processes in living cells involve clusters of particles. Such processes include protein aggregation and the development of intracellular concentration gradients. To study these mechanisms, we can apply coagulation-fragmentation models describing populations of interacting components. In this context, the Becker-Döring equations - theorized in 1935 - provide the simplest kinetic model to describe condensations phenomena. Experimental works on this model reveal that it exhibits robustness, defined as the system’s capability to preserve its features despite noise and fluctuations. Here, we verify the robustness of the BD model, applying our notions of initial concentration robustness (α -robustness and β -robustness), which are related to the influence of the perturbation of the initial concentration of one species (i.e., the input) on the concentration of another species (i.e., the output) at the steady state. Then, we conclude that a new definition of robustness, namely the asymptotic robustness, is necessary to describe more accurately the model’s behavior
Inauguration of the Centro 3R for the promotion of 3Rs principles in teaching and research.
No full textthe first European interuniversity center dedicated to promoting 3Rs principles in teaching and research was inaugurated in Pisa, Italy on March 14, 2018. The Centro 3R was spearheaded
by the Universities of Pisa and Genoa. Membership is open to all Italian universities and agreements for twinning across Europe and other countries are being pursued. the Centro’s mission to promote rational and scientific thinking in experimental science through a multidisciplinary teaching and research approach inclusive of all 3Rs as a means to accelerate the R of
replacement. The projects to develop an open resource-sharing web platform and interdisciplinary elective courses were also mentioned
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