YAPA: A generic tool for computing intruder knowledge

Reasoning about the knowledge of an attacker is a necessary step in many formal analyses of security protocols. In the framework of the applied pi calculus, as in similar languages based on equational logics, knowledge is typically expressed by two relations: deducibility and static equivalence. Several decision procedures have been proposed for these relations under a variety of equational theories. However, each theory has its particular algorithm, and none has been implemented so far. We provide a generic procedure for deducibility and static equivalence that takes as input any convergent rewrite system. We show that our algorithm covers most of the existing decision procedures for convergent theories. We also provide an efficient implementation, and compare it briefly with the tools ProVerif and KiSs

Automating Security Analysis: Symbolic Equivalence of Constraint Systems

We consider security properties of cryptographic protocols, that are either trace properties (such as confidentiality or authenticity) or equivalence properties (such as anonymity or strong secrecy). Infinite sets of possible traces are symbolically represented using deducibility constraints. We give a new algorithm that decides the trace equivalence for the traces that are represented using such constraints, in the case of signatures, symmetric and asymmetric encryptions. Our algorithm is implemented and performs well on typical benchmarks. This is the first implemented algorithm, deciding symbolic trace equivalence

Probing quantum and classical turbulence analogy through global bifurcations in a von K\'arm\'an liquid Helium experiment

We report measurements of the dissipation in the Superfluid Helium high REynold number von Karman flow (SHREK) experiment for different forcing conditions, through a regime of global hysteretic bifurcation. Our macroscopical measurements indicate no noticeable difference between the classical fluid and the superfluid regimes, thereby providing evidence of the same dissipative anomaly and response to asymmetry in fluid and superfluid regime. %In the latter case, A detailed study of the variations of the hysteretic cycle with Reynolds number supports the idea that (i) the stability of the bifurcated states of classical turbulence in this closed flow is partly governed by the dissipative scales and (ii) the normal and the superfluid component at these temperatures (1.6K) are locked down to the dissipative length scale.Comment: 5 pages, 5 figure

A Physical Approach for Stochastic Modeling of TERO-based TRNG

International audienceSecurity in random number generation for cryptography is closely related to the entropy rate at the generator output. This rate has to be evaluated using an appropriate stochastic model. The stochastic model proposed in this paper is dedicated to the transition effect ring oscillator (TERO) based true random number generator (TRNG) proposed by Varchola and Drutarovsky in 2010. The advantage and originality of this model is that it is derived from a physical model based on a detailed study and on the precise electrical description of the noisy physical phenomena that contribute to the generation of random numbers. We compare the proposed electrical description with data generated in a 28 nm CMOS ASIC implementation. Our experimental results are in very good agreement with those obtained with both the physical model of TERO's noisy behavior and with the stochastic model of the TERO TRNG, which we also confirmed using the AIS 31 test suites

Cophylogeny reconstruction via an approximate bayesian computation

Despite an increasingly vast literature on cophylogenetic reconstructions for studying host-parasite associations, understanding the common evolutionary history of such systems remains a problem that is far from being solved. Most algorithms for host-parasite reconciliation use an event-based model, where the events include in general (a subset of) cospeciation, duplication, loss, and host switch. All known parsimonious event-based methods then assign a cost to each type of event in order to find a reconstruction of minimum cost. The main problem with this approach is that the cost of the events strongly influences the reconciliation obtained. Some earlier approaches attempt to avoid this problem by finding a Pareto set of solutions and hence by considering event costs under some minimization constraints. To deal with this problem, we developed an algorithm, called Coala, for estimating the frequency of the events based on an approximate Bayesian computation approach. The benefits of this method are 2-fold: (i) it provides more confidence in the set of costs to be used in a reconciliation, and (ii) it allows estimation of the frequency of the events in cases where the data set consists of trees with a large number of taxa. We evaluate our method on simulated and on biological data sets. We show that in both cases, for the same pair of host and parasite trees, different sets of frequencies for the events lead to equally probable solutions. Moreover, often these solutions differ greatly in terms of the number of inferred events. It appears crucial to take this into account before attempting any further biological interpretation of such reconciliations. More generally, we also show that the set of frequencies can vary widely depending on the input host and parasite trees. Indiscriminately applying a standard vector of costs may thus not be a good strategy

Excavation at Aguas Buenas, Robinson Crusoe Island, Chile, of a gunpowder magazine and the supposed campsite of Alexander Selkirk, together with an account of early navigational dividers

Excavations were undertaken of a ruined building at Aguas Buenas, identified as an 18th-century Spanish gunpowder magazine. Evidence was also found for the campsite of an early European occupant of the island. A case is made that this was Alexander Selkirk, a castaway here from 1704 to 1709. Selkirk was the model for Defoe’s Robinson Crusoe. A detailed discussion is given of a fragment of copper alloy identifi ed as being from a pair of navigational dividers

Intermediate-term results after en bloc double-lung transplantation with bronchial arterial revascularization

AbstractObjective: Between May 1990 and January 1994, 18 patients underwent en bloc double-lung transplantation with tracheal anastomosis and bronchial arterial revascularization. Because at that time it was already suggested that chronic ischemia could be a contributing factor in occurrence of obliterative bronchiolitis, the purpose of this study was to evaluate, with a follow-up ranging from 22 to 69 months, the midterm effects of bronchial arterial revascularization on development of obliterative bronchiolitis. Results: Results were assessed according to tracheal healing, functional results, rejection, infection, and incidence of obliterative bronchiolitis. There were no intraoperative deaths or reexplorations for bleeding related to bronchial arterial revascularization, but there were three hospital deaths and five late deaths, two of them related to obliterative bronchiolitis. According to the criteria previously defined, tracheal healing was assessed as grade I, IIa, or IIb in 17 patients and grade IIIa in only one patient. Early angiography (postoperative days 20 to 40) demonstrated a patent graft in 11 of the 14 patients in whom follow-up information was obtained. Ten patients are currently alive with a 43-month mean follow-up. Among the 15 patients surviving more than 1 year, functional results have been excellent except in five in whom obliterative bronchiolitis has developed and who had an early or late graft thrombosis. Furthermore, those patients had a significantly higher incidence of late acute rejection (p < 0.02), cytomegalovirus disease (p < 0.006), and bronchitis episodes (p < 0.0008) than patients free from obliterative bronchiolitis. Conclusion: We conclude that besides its immediate beneficial effect on tracheal healing, long-lasting revascularization was, at least in this small series, associated with an absence of obliterative bronchiolitis, thus suggesting but not yet proving the possible role of chronic ischemia in this multifactorial disease. (J THORAC CARDIOVASC SURG 1996;112:1292-300

Thromboembolism and bleeding in systemic amyloidosis: a review

The assessment of both thromboembolic and haemorrhagic risks and their management in systemic amyloidosis have been poorly emphasized so far. This narrative review summarizes main evidence from literature with clinical perspective. The rate of thromboembolic events is as high as 5–10% amyloidosis patients, at least in patients with cardiac involvement, with deleterious impact on prognosis. The most known pro-thrombotic factors are heart failure, atrial fibrillation, and atrial myopathy. Atrial fibrillation could occur in 20% to 75% of systemic amyloidosis patients. Cardiac thrombi are frequently observed in patients, particularly in immunoglobulin light chains (AL) amyloidosis, up to 30%, and it is advised to look for them systematically before cardioversion. In AL amyloidosis, nephrotic syndrome and the use of immunomodulatory drugs also favour thrombosis. On the other hand, the bleeding risk increases because of frequent amyloid digestive involvement as well as factor X deficiency, renal failure, and increased risk of dysautonomia-related fall

Scattering of first and second sound waves by quantum vorticity in superfluid Helium

We study the scattering of first and second sound waves by quantum vorticity in superfluid Helium using two-fluid hydrodynamics. The vorticity of the superfluid component and the sound interact because of the nonlinear character of these equations. Explicit expressions for the scattered pressure and temperature are worked out in a first Born approximation, and care is exercised in delimiting the range of validity of the assumptions needed for this approximation to hold. An incident second sound wave will partly convert into first sound, and an incident first sound wave will partly convert into second sound. General considerations show that most incident first sound converts into second sound, but not the other way around. These considerations are validated using a vortex dipole as an explicitely worked out example.Comment: 24 pages, Latex, to appear in Journal of Low Temperature Physic

A Cryogenic High-Reynolds Turbulence Experiment at CERN

The potential of cryogenic helium flows for studying high-Reynolds number turbulence in the laboratory has been recognised for a long time and implemented in several small-scale hydrodynamic experiments. With its large superconducting particle accelerators and detector magnets, CERN, the European Laboratory for Particle Physics, has become a major world center in helium cryogenics, with several large helium refrigerators having capacities up to 18 kW @ 4.5 K. Combining a small fraction of these resources with the expertise of three laboratories at the forefront of turbulence research, has led to the design, swift implementation, and successful operation of GReC (Grands Reynolds Cryogéniques) a large axisymmetric turbulent-jet experiment. With flow-rates up to 260 g/s of gaseous helium at ~ 5 K and atmospheric pressure, Reynolds numbers up to 107 have been achieved in a 4.6 m high, 1.4 m diameter cryostat. This paper presents the results of the first runs and describes the experimental set-up comprehensively equipped with "hot" wire micro-anemometers, acoustic scattering vorticity measurements and a large-bandwidth data acquisition system