Concurrent Computing with Shared Replicated Memory

The behavioural theory of concurrent systems states that any concurrent system can be captured by a behaviourally equivalent concurrent Abstract State Machine (cASM). While the theory in general assumes shared locations, it remains valid, if different agents can only interact via messages, i.e. sharing is restricted to mailboxes. There may even be a strict separation between memory managing agents and other agents that can only access the shared memory by sending query and update requests to the memory agents. This article is dedicated to an investigation of replicated data that is maintained by a memory management subsystem, whereas the replication neither appears in the requests nor in the corresponding answers. We show how the behaviour of a concurrent system with such a memory management can be specified using concurrent communicating ASMs. We provide several refinements of a high-level ground model addressing different replication policies and internal messaging between data centres. For all these refinements we analyse their effects on the runs such that decisions concerning the degree of consistency can be consciously made.Comment: 23 page

Systematic reconstruction of TRANSPATH data into Cell System Markup Language

<p>Abstract</p> <p>Background</p> <p>Many biological repositories store information based on experimental study of the biological processes within a cell, such as protein-protein interactions, metabolic pathways, signal transduction pathways, or regulations of transcription factors and miRNA. Unfortunately, it is difficult to directly use such information when generating simulation-based models. Thus, modeling rules for encoding biological knowledge into system-dynamics-oriented standardized formats would be very useful for fully understanding cellular dynamics at the system level.</p> <p>Results</p> <p>We selected the TRANSPATH database, a manually curated high-quality pathway database, which provides a plentiful source of cellular events in humans, mice, and rats, collected from over 31,500 publications. In this work, we have developed 16 modeling rules based on hybrid functional Petri net with extension (HFPNe), which is suitable for graphical representing and simulating biological processes. In the modeling rules, each Petri net element is incorporated with Cell System Ontology to enable semantic interoperability of models. As a formal ontology for biological pathway modeling with dynamics, CSO also defines biological terminology and corresponding icons. By combining HFPNe with the CSO features, it is possible to make TRANSPATH data to simulation-based and semantically valid models. The results are encoded into a biological pathway format, Cell System Markup Language (CSML), which eases the exchange and integration of biological data and models.</p> <p>Conclusion</p> <p>By using the 16 modeling rules, 97% of the reactions in TRANSPATH are converted into simulation-based models represented in CSML. This reconstruction demonstrates that it is possible to use our rules to generate quantitative models from static pathway descriptions.</p

Concurrent abstract state machines

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A Reduction Theory For Coloured Nets

This paper presents the generalization for the coloured nets of the most efficient reductions defined by Berthelot for Petri nets. First a methodology of the generalization is given which is independent from the reduction one wants to generalize. Then based on this methodology, we define extensions of the implicit place transformation and the pre and post agglomeration of transitions. For each reduction we prove that the reduced net has exactly the same properties as the original net. Finally we completely reduce an improved modelling of the data base management with multiple copies showing, by this way, its correctness. INTRODUCTION In any theoretical model of computation, a useful method to prove properties of an object (program, protocol, ...) of this model is to reduce this object such that the simplified object has the same properties as the original one. In his thesis, Berthelot [Ber83] has defined ten reductions of Petri nets and has shown how they can be efficiently used in ..

Can you be allergic to your Wi-Fi?

Electromagnetic fields are all around us. They are a part of our natural environment, produced by the Earth and the sun. But they are also becoming increasingly prominent with advancements in technology, such that we are surrounded daily by many different sources of electromagnetic energy. Mobile phones, Wi-Fi, personal computers, smart meters, radio, television and even the TV remote control - they all emit this kind of energy. Mobile phone base stations are continually being installed, and Wi-Fi hotspots are increasing all of the time. Cafés and restaurants, libraries, hotels and even some city centres and parks now offer free Wi-Fi. But with all of this new infrastructure it is also getting harder to avoid exposure to the electromagnetic fields that these technologies emit. And the question often asked is what does all of this exposure mean for our health? It is an issue that has continued to gain exposure, culminating this month in what\u27s being touted as a breakthrough case, with a French woman being awarded compensation for an allergy to Wi-Fi. Martine Richard, who suffers from what is called electromagnetic hypersensitivity (EHS), was granted disability payments due to claims that her symptoms, which she attributes to electromagnetic energy, prevent her from being able to work. This ruling was made despite the science saying that no relationship between exposure to these fields and symptoms exists. So what is EHS, what do we know and what don\u27t we know about this condition? And what does this case mean for the future