Integrating discrete- and continuous-time metric temporal logics through sampling

Abstract. Real-time systems usually encompass parts that are best described by a continuous-time model, such as physical processes under control, together with other components that are more naturally formalized by a discrete-time model, such as digital computing modules. Describing such systems in a unified framework based on metric temporal logic requires to integrate formulas which are interpreted over discrete and continuous time. In this paper, we tackle this problem with reference to the metric temporal logic TRIO, that admits both a discrete-time and a continuous-time semantics. We identify sufficient conditions under which TRIO formulas have a consistent truth value when moving from continuous-time to discrete-time interpretations, or vice versa. These conditions basically involve the restriction to a proper subset of the TRIO language and a requirement on the finite variability over time of the basic items in the specification formulas. We demonstrate the approach with an example of specification and verification

The phase diagram of the extended anisotropic ferromagnetic-antiferromagnetic Heisenberg chain

By using Density Matrix Renormalization Group (DMRG) technique we study the phase diagram of 1D extended anisotropic Heisenberg model with ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions. We analyze the static correlation functions for the spin operators both in- and out-of-plane and classify the zero-temperature phases by the range of their correlations. On clusters of $64,100,200,300$ sites with open boundary conditions we isolate the boundary effects and make finite-size scaling of our results. Apart from the ferromagnetic phase, we identify two gapless spin-fluid phases and two ones with massive excitations. Based on our phase diagram and on estimates for the coupling constants known from literature, we classify the ground states of several edge-sharing materials.Comment: 12 pages, 13 figure

Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry

Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase

A sub-quadratic algorithm for conjunctive and disjunctive boolean equation systems

We present a new algorithm for conjunctive and disjunctive boolean equation systems which arise frequently in the verification and analysis of finite state concurrent systems. In contrast to the previously known O(e 2) time algorithms, our algorithm computes the solution to such a fixpoint equation system with size e and alternation depth d in O(e log d) time (here d <e). We show the correctness and complexity of the algorithm. We discuss heuristics and describe how the algorithm can be efficiently implemented. The algorithm is compared to a previous solution via experiments on verification examples. Our measurements indicate that the new algorithm makes the verification of a large class of fixpoint expressions more tractable

Digitizing Interval Duration Logic

Interval Duration Logic, (IDL), is a dense time logic for specifying properties of real-time systems. Its validity is undecidable. A corresponding discrete-time logic QDDC has decidable validity. In this paper, we consider a reduction of IDL validity question to QDDC validity using notions of digitization. A new notion of Strong Closure under Inverse Digitization, SCID, is proposed. It is shown that for all SCID formulae, the dense and the discrete-time validity coincide. Moreover, SCID has good algebraic properties which allows us to conveniently prove that many interesting IDL formulae are in fact SCID. We also give some approximation techniques to strengthen/weaken formulae to SCID form. We illustrate the use of this approach by an example where a densetime IDL formula is digitized and then verified using the QDDC validity checker, DCVALID

<i>Ralstonia eutropha</i>, containing high poly-β-hydroxybutyrate levels, regulates the immune response in mussel larvae challenged with <i>Vibrio coralliilyticus</i>

Marine invertebrates rely mainly on innate immune mechanisms that include both humoral and cellular responses. Antimicrobial peptides (AMPs), lysozyme and phenoloxidase activity, are important components of the innate immune defensesystem in marine invertebrates. They provide an immediate and rapid response to invading microorganisms. The impact of amorphous poly-β-hydroxybutyrate (PHB-A) (1 mg PHB-A L−1) on gene expression of the AMPs mytimycin, mytilinB, defensin and the hydrolytic enzyme lysozyme in infected blue mussel larvae was investigated during “in vivo” challenge tests with Vibrio coralliilyticus (105 CFU mL−1). RNAs were isolated from mussel larvae tissue, and AMPs were quantified by q-PCR using the 18srRNA gene as a housekeeping gene. Our data demonstrated that AMPs genes had a tendency to be upregulated in challenged mussel larvae, and the strongest expression was observed from 24 h post-exposure onwards. The presence of both PHB-A and the pathogen stimulated the APMs gene expression, however no significant differences were noticed between treatments or between exposure time to the pathogen V. coralliilyticus. Looking at the phenoloxidase activity in the infected mussels, it was observed that the addition of PHB-A significantly increased the activity

Another Fallen Hash-Based RFID Authentication Protocol

Abstract. In this paper, we scrutinize the security of an RFID protocol [9], which has been recently proposed, and show important vulnerabilities. Our first attack is a passive one that can disclose all secret information stored on the tags ’ memory. We only need to eavesdrop one session of the protocol between a tag and a legitimate reader (connected to the back-end database) and perform O(2 17)off-line evaluations of the PRNG-function – while the authors wrongly claimed the complexity of any such attack would be around 2 48 operations. Although the extracted information is enough to launch other relevant attacks and thus to completely rule out any of the protocol’s security claims, we additionally present several attacks using alternative strategies that show the protocol is flawed in more than one way and has many exploitable weaknesses. More precisely, we present a tag impersonation attack that requires the execution of only two runs of the protocol, and has a success probability of 1. It must be noted that this attack is, however, not applicable to the original protocol that the authors attempted to improve so, in a way, their improvement is not such. Finally, we show two approaches to trace a tag, as long as it has not updated its secret values. For all the above, we conclude that the improved protocol is even less secure than the original proposal, which is also quite insecure, and cannot be recommended