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1

A Causal View on Non-Interference

Baldan P., Carraro A.

Fundamenta Informaticae

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2015

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Vol. 140, nr 1

1--38

EN

The concept of non-interference has been introduced to characterise the absence of undesired information flows in a computing system. Although it is often explained referring to an informal notion of causality - the activity involving the part of the system with higher level of confidentiality should not cause any observable effect at lower levels - it is almost invariably formalised in terms of interleaving semantics. Here we focus on Petri nets and on the BNDC (Bisimilarity-based Non-Deducibility on Composition) property, a formalisation of non-interference widely studied in the literature. We show that BNDC admits natural characterisations based on the unfolding semantics - a classical true concurrent semantics for Petri nets - in terms of causalities and conflicts between high and low level activities. This leads to algorithms for checking BNDC on various classes of Petri nets, based on the construction of suitable complete prefixes of the unfolding. We also developed a prototype tool UBIC (Unfolding-Based Interference Checker), working on safe Petri nets, which provides promising results in terms of efficiency.

2

Branching Processes of General Petri Nets

Couvreur J. M., Poitrenaud D., Weil P.

Fundamenta Informaticae

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2013

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Vol. 122, nr 1-2

31--58

EN

We propose a new model of branching processes, suitable for describing the behavior of general Petri nets, without any finiteness or safeness assumption. In this framework, we define a new class of branching processes and unfoldings of a net N, which we call faithful. These coincide with the safe branching processes and unfoldings if N is safe, or weakly safe as in [Engelfriet 1991], but not in general. However, faithful branching processes and processes satisfy the good order-theoretic properties which make the safe processes of safe nets so useful in practice, and which are known not to hold for the safe processes of a general net. Faithful processes represent therefore good candidates to generalize the theory of safe nets to the general case.

3

Application of LiF : Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) for experimental verification of radial dose distribution models

Gieszczyk W., Olko P., Bilski P., Grzanka L., Obryk B., Horwacik T.

Nukleonika

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2012

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Vol. 57, No. 4

507-512

EN

In track structure theory, the radial distribution of dose, D(r), around an ion track plays a fundamental role in predicting the response of biological systems and physical detectors after a dose (or fluence) of ions. According to the formulations of D(r), the local dose at radial distances below 1 nm can reach values as high as 106 Gy. We propose a new method of verifying experimentally the radial dose distribution around alfa-particle tracks, using LiF:Mg,Cu,P (MCP-N) thermoluminescent detectors (TLD) which are able to measure gamma-ray doses in the kGy range via evaluation of their high-temperature TL glow peak structure over the temperature range of 350–550 centigrade. MCP-N detectors were irradiated with Am-241 alfa-particles at fluences ranging from 107 to 1011 particles/cm2, and by Co-60 gamma-ray doses ranging from several Gy up to the MGy. A number N of individual high-temperature TL peaks were analysed in the obtained glow curves by deconvolution, using the GlowFit code. For each of these peaks, an equation relating the intensity, A, of the TL signal obtained after alfa-particle irradiation and after gamma-ray doses, via the dose-frequency function, f alfa(D), was written in the form: A i alfa = integral A i gamma(D)x f alfa (D)dD, i 1,.., N. Using this set of N equations, where A alfa i and A gamma i(D) were known (measured), the single unknown function f alfa(D) was unfolded and converted to D(r). Parametric unfolding and the SAND-II iterative code were applied. While we were able to confirm the 1/r2 dependence of D(r) in agreement with D(r) expressions, we were unable to conclusively evaluate the dependence of D(r) at intermediate ranges of radial distance r. This preliminary result of our unique experimental approach to determine the radial dose distribution around the path of heavy charged particles in LiF detectors, requires further development.

4

Protein conformational changes induced by adsorption onto material surfaces: an important issue for biomedical applications of material science

Ballet T., Boulange L., Brechet Y., Bruckert F., Weidenhaupt M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2010

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Vol. 58, nr 2

303-315

EN

Protein adsorption on solid surfaces is a widespread phenomenon of large biological and biotechnological significance. Conformational changes are likely to accompany protein adsorption, but are difficult to evidence directly. Nevertheless they have important consequences, since the partial unfolding of protein domains can expose hitherto hidden amino acids. This remodeling of the protein surface can trigger the activation of molecular complexes such as the blood coagulation cascade or the innate immune complement system. In the case of extracellular matrix, it can also change the way cells interact with the material surfaces and result in modified cell behavior. In this review, we present direct and indirect evidences that support the view that some proteins change their conformation upon adsorption. We also show that both physical and chemical methods are needed to study the extent and kinetics of protein conformational changes. In particular, AFM techniques and cryo-electron microscopy provide useful and complementary information. We then review the chemical and topological features of both proteins and material surfaces in relation with protein adsorption. Mutating key amino acids in proteins changes their stability and this is related to material-induced conformational changes, as shown for instance with insulin. In addition, combinatorial methods should provide valuable information about peptide or antibody adsorption on well-defined material surfaces. These techniques could be combined with molecular modeling methods to decipher the rules governing conformational changes associated with protein adsorption.

5

Komputerowa symulacja procesu składania i rozkładania ramy nośnej narzędzia rolniczego

Zbytek Z., Łowiński Ł., Talarczyk W.

Journal of Research and Applications in Agricultural Engineering

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2007

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Vol. 52, nr 2

16-20

PL

Omówiono symulacje komputerowe procesu składania i rozkładania ramy nośnej narzędzia rolniczego przeprowadzone w fazie projektowania. Opracowany model geometryczny ramy nośnej poddano analizie wpływu zmiany położenia narzędzia na reakcje w punktach zawieszenia na ciągniku, wpływu zmiany położenia ramion bocznych ramy na reakcje w miejscach mocowania siłowników oraz określono położenie i kształt zderzaków i łącznika. W wyniku podjętych prac uzyskano konstrukcję belki nośnej narzędzia rolniczego stanowiącą podstawę do przeprowadzenia analizy wytrzymałościowej modelu obliczeniowego MES całej konstrukcji wielofunkcyjnego narzędzia uprawowo-pielęgnacyjnego.

EN

Computer simulations of the process of folding and unfolding of main frame of agricultural implement which were carried out and the phase of designing are discussed in the paper. Elaborated geometrical model of the mainframe was put to the analysis to determine the influence of implement position changes on reactions in the points of its mounting on the tractor as well as to determine the influence of changes of positions of the frame side arms on reactions in the points where hydraulic cylinders are fixed. Then the location and shape of the stops and the connecting rod were determined. As a result of these works created was construction of the agricultural implement main beam which will be a base for carrying out strength analysis of calculation model FEM of the whole construction of the agricultural multifunctional implement.