Salinity effects on biodegradation of Reactive Black 5 for one stage and two stages sequential anaerobic aerobic biological processes employing different anaerobic sludge

In this study the effect of NaCl, normally found in dye bath wastewaters employing reactive azo dyes, on the performance of sequential anaerobic-aerobic processes for treatment of Reactive Black 5 (RB5) containing media, with concentration in the range 100-500mgL-1, was investigated. Three possible scenarios of the sequential anaerobic-aerobic process, namely two stage process and one stage processes employing either anaerobic or activated sludge, were considered. The results showed a statistically significant enhancement of the anaerobic decolourisation efficiency as a result of the addition of 30gL-1 NaCl to the RB5 containing media for two stage processes and one stage processes employing anaerobic sludge. NaCl at 30gL-1 concentration also inhibited aerobic colour formation during two stage processes whereas it prevented aerobic decolourisation during one stage processes. HPLC and UV Vis analysis indicated that during anaerobic phase/stage the majority of azo bonds in RB5 molecules cleave whereas the hydrophobicity/MW of the resulting dye reduction metabolites decreases. The same analysis revealed partial mineralisation of RB5 reduction metabolites under aerobic conditions. The results of the present work also showed that the effect of salt on anaerobic decolourisation efficiency, TVFA and methane production was dependent on the exposure history of anaerobic sludge

Constraint-Based Monitoring of Hyperproperties

Verifying hyperproperties at runtime is a challenging problem as hyperproperties, such as non-interference and observational determinism, relate multiple computation traces with each other. It is necessary to store previously seen traces, because every new incoming trace needs to be compatible with every run of the system observed so far. Furthermore, the new incoming trace poses requirements on future traces. In our monitoring approach, we focus on those requirements by rewriting a hyperproperty in the temporal logic HyperLTL to a Boolean constraint system. A hyperproperty is then violated by multiple runs of the system if the constraint system becomes unsatisfiable. We compare our implementation, which utilizes either BDDs or a SAT solver to store and evaluate constraints, to the automata-based monitoring tool RVHyper

Parallelizing Deadlock Resolution in Symbolic Synthesis of Distributed Programs

Previous work has shown that there are two major complexity barriers in the synthesis of fault-tolerant distributed programs: (1) generation of fault-span, the set of states reachable in the presence of faults, and (2) resolving deadlock states, from where the program has no outgoing transitions. Of these, the former closely resembles with model checking and, hence, techniques for efficient verification are directly applicable to it. Hence, we focus on expediting the latter with the use of multi-core technology. We present two approaches for parallelization by considering different design choices. The first approach is based on the computation of equivalence classes of program transitions (called group computation) that are needed due to the issue of distribution (i.e., inability of processes to atomically read and write all program variables). We show that in most cases the speedup of this approach is close to the ideal speedup and in some cases it is superlinear. The second approach uses traditional technique of partitioning deadlock states among multiple threads. However, our experiments show that the speedup for this approach is small. Consequently, our analysis demonstrates that a simple approach of parallelizing the group computation is likely to be the effective method for using multi-core computing in the context of deadlock resolution

Brief announcement: incremental component-based modeling, verification, and performance evaluation of distributed reset

In this work, we apply a methodology which consistently integrates modeling, verification, and performance evaluation techniques, based on the BIP (Behavior, Interaction, Priority) component framework developed at Verimag [A. Basu et al., 2006; A. Basu et al., 2008]. BIP is based on a semantic model encompassing composition of heterogeneous components. The distributed semantics of BIP allows generating from a high-level component-based model in BIP an observationally equivalent distributed implementation [A. Basu et al., 2008]. BIP uses two families of composition operators for expressing coordination between components: interactions and priorities. Interactions may involve multiple components (unlike traditional point-to-point formalisms) and are expressed by combining two protocols: rendezvous and broadcast. We note that addition of interactions among components adds no extra behaviors

Realizing Omega-regular Hyperproperties

We studied the hyperlogic HyperQPTL, which combines the concepts of trace relations and $\omega$-regularity. We showed that HyperQPTL is very expressive, it can express properties like promptness, bounded waiting for a grant, epistemic properties, and, in particular, any $\omega$-regular property. Those properties are not expressible in previously studied hyperlogics like HyperLTL. At the same time, we argued that the expressiveness of HyperQPTL is optimal in a sense that a more expressive logic for $\omega$-regular hyperproperties would have an undecidable model checking problem. We furthermore studied the realizability problem of HyperQPTL. We showed that realizability is decidable for HyperQPTL fragments that contain properties like promptness. But still, in contrast to the satisfiability problem, propositional quantification does make the realizability problem of hyperlogics harder. More specifically, the HyperQPTL fragment of formulas with a universal-existential propositional quantifier alternation followed by a single trace quantifier is undecidable in general, even though the projection of the fragment to HyperLTL has a decidable realizability problem. Lastly, we implemented the bounded synthesis problem for HyperQPTL in the prototype tool BoSy. Using BoSy with HyperQPTL specifications, we have been able to synthesize several resource arbiters. The synthesis problem of non-linear-time hyperlogics is still open. For example, it is not yet known how to synthesize systems from specifications given in branching-time hyperlogics like HyperCTL$^*$.Comment: International Conference on Computer Aided Verification (CAV 2020

Fully-automated Runtime Enforcement of Component-based Systems with Formal and Sound Recovery

International audienceWe introduce runtime enforcement of specifications on component-based systems (CBS) modeled in the BIP (Behavior, Interaction and Priority) framework. Runtime enforcement is an increasingly popular and effective dynamic validation technique aiming to ensure the correct runtime behavior (w.r.t. a formal specification) of a system using a so-called enforcement monitor. BIP is a powerful and expressive component-based framework for the formal construction of heterogeneous systems. Because of BIP expressiveness however , it is difficult to enforce complex behavioral properties at design-time. We first introduce a theoretical runtime enforcement framework for component-based systems where we delineate a hierarchy of enforceable properties (i.e., properties that can be enforced) according to the number of observational steps a system is allowed to deviate from the property (i.e., the notion of k-step enforceability). To ensure the observational equivalence between the correct executions of the initial system and the monitored system, we show that i) only stutter-invariant properties should be enforced on CBS with our monitors, and ii) safety properties are 1-step enforceable. Second, given an abstract enforcement monitor for some 1-step enforceable property, we define a series of formal transformations to instrument (at relevant locations) a CBS described in the BIP framework to integrate the monitor. At runtime, the monitor observes and automatically avoids any error in the behavior of the system w.r.t. the property. Third, our approach is fully implemented in RE-BIP, an available tool integrated in the BIP tool suite. Fourth, to validate our approach, we use RE-BIP to i) enforce deadlock-freedom on a dining philosophers benchmark, and ii) ensure the correct placement of robots on a map

Neural plasticity and treatment-induced recovery of sentence processing and production in agrammatism

Six agrammatic speakers were trained on production and processing of object-relative sentence structures, resulting in generalization to less complex sentence structures. The acquired structure-building process reflected by this generalization was shown to be supported by changes in neuronal activation patterns underlying syntactic task execution, as measured with pre and post training functional MRIs. The most prominent neuronal activity upregulation was seen in posterior temporoparietal cortical areas, outside of the core network activated in a group of healthy control subjects during complex syntactic processing

Explainable Reactive Synthesis

Reactive synthesis transforms a specification of a reactive system, given in a temporal logic, into an implementation. The main advantage of synthesis is that it is automatic. The main disadvantage is that the implementation is usually very difficult to understand. In this paper, we present a new synthesis process that explains the synthesized implementation to the user. The process starts with a simple version of the specification and a corresponding simple implementation. Then, desired properties are added one by one, and the corresponding transformations, repairing the implementation, are explained in terms of counterexample traces. We present SAT-based algorithms for the synthesis of repairs and explanations. The algorithms are evaluated on a range of examples including benchmarks taken from the SYNTCOMP competition

Neural Correlates of Verb Argument Structure Processing

This fMRI study examined the neural correlates of verbs controlled for argument structure complexity and nouns controlled for semantic class. Participants showed activation of left inferior frontal and posterior temporal regions for verbs as compared to nouns, and more widespread, non-perisylvian activation for nouns as compared to verbs. Verbs with more complex argument structure entries activated posterior temporal regions bilaterally. These findings suggest that posterior perisylvian regions are crucial for processing the argument structure information associated with verbs