Synchrony vs. Causality in Asynchronous Petri Nets

Given a synchronous system, we study the question whether the behaviour of that system can be exhibited by a (non-trivially) distributed and hence asynchronous implementation. In this paper we show, by counterexample, that synchronous systems cannot in general be implemented in an asynchronous fashion without either introducing an infinite implementation or changing the causal structure of the system behaviour.Comment: In Proceedings EXPRESS 2011, arXiv:1108.407

Synchrony versus causality in distributed systems

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Given a synchronous system, we study the question whether – or, under which conditions – the behaviour of that system can be realized by a (non-trivially) distributed and hence asynchronous implementation. In this paper, we partially answer this question by examining the role of causality for the implementation of synchrony in two fundamental different formalisms of concurrency, Petri nets and the π-calculus. For both formalisms it turns out that each ‘good’ encoding of synchronous interactions using just asynchronous interactions introduces causal dependencies in the translation

Synchrony versus causality in distributed systems

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Given a synchronous system, we study the question whether – or, under which conditions – the behaviour of that system can be realized by a (non-trivially) distributed and hence asynchronous implementation. In this paper, we partially answer this question by examining the role of causality for the implementation of synchrony in two fundamental different formalisms of concurrency, Petri nets and the π-calculus. For both formalisms it turns out that each ‘good’ encoding of synchronous interactions using just asynchronous interactions introduces causal dependencies in the translation

New Platform Technology for Comprehensive Serological Diagnostics of Autoimmune Diseases

Antibody assessment is an essential part in the serological diagnosis of autoimmune diseases. However, different diagnostic strategies have been proposed for the work up of sera in particular from patients with systemic autoimmune rheumatic disease (SARD). In general, screening for SARD-associated antibodies by indirect immunofluorescence (IIF) is followed by confirmatory testing covering different assay techniques. Due to lacking automation, standardization, modern data management, and human bias in IIF screening, this two-stage approach has recently been challenged by multiplex techniques particularly in laboratories with high workload. However, detection of antinuclear antibodies by IIF is still recommended to be the gold standard method for antibody screening in sera from patients with suspected SARD. To address the limitations of IIF and to meet the demand for cost-efficient autoantibody screening, automated IIF methods employing novel pattern recognition algorithms for image analysis have been introduced recently. In this respect, the AKLIDES technology has been the first commercially available platform for automated interpretation of cell-based IIF testing and provides multiplexing by addressable microbead immunoassays for confirmatory testing. This paper gives an overview of recently published studies demonstrating the advantages of this new technology for SARD serology

Attracting AID to targets of somatic hypermutation

The process of somatic hypermutation (SHM) of immunoglobulin (Ig) genes requires activation-induced cytidine deaminase (AID). Although mistargeting of AID is detrimental to genome integrity, the mechanism and the cis-elements responsible for targeting of AID are largely unknown. We show that three CAGGTG cis-elements in the context of Ig enhancers are sufficient to target SHM to a nearby transcribed gene. The CAGGTG motif binds E47 in nuclear extracts of the mutating cells. Replacing CAGGTG with AAGGTG in the construct without any other E47 binding site eliminates SHM. The CA versus AA effect requires AID. CAGGTG does not enhance transcription, chromatin acetylation, or overall target gene activity. The other cis-elements of Ig enhancers alone cannot attract the SHM machinery. Collectively with other recent findings, we postulate that AID targets all genes expressed in mutating B cells that are associated with CAGGTG motifs in the appropriate context. Ig genes are the most highly mutated genes, presumably because of multiple CAGGTG motifs within the Ig genes, high transcription activity, and the presence of other cooperating elements in Ig enhancers

The activation-induced cytidine deaminase (AID) efficiently targets DNA in nucleosomes but only during transcription

The activation-induced cytidine deaminase (AID) initiates somatic hypermutation, class-switch recombination, and gene conversion of immunoglobulin genes. In vitro, AID has been shown to target single-stranded DNA, relaxed double-stranded DNA, when transcribed, or supercoiled DNA. To simulate the in vivo situation more closely, we have introduced two copies of a nucleosome positioning sequence, MP2, into a supercoiled AID target plasmid to determine where around the positioned nucleosomes (in the vicinity of an ampicillin resistance gene) cytidine deaminations occur in the absence or presence of transcription. We found that without transcription nucleosomes prevented cytidine deamination by AID. However, with transcription AID readily accessed DNA in nucleosomes on both DNA strands. The experiments also showed that AID targeting any DNA molecule was the limiting step, and they support the conclusion that once targeted to DNA, AID acts processively in naked DNA and DNA organized within transcribed nucleosomes

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Die Sieben Todsünden

Weshalb faszinieren und inspirieren die Sieben Todsünden bis heute – auch und gerade obwohl theologische Kommentare längst an Verbindlichkeit eingebüßt haben? In exemplarischen Studien widmet sich der Sammelband der Wirkungsgeschichte der Sieben Todsünden in den unterschiedlichen Künsten: Literatur und bildende Kunst, Film und Fernsehen. Der Fokus liegt weniger auf einer Ideengeschichte der Todsünden als auf deren Formelhaftigkeit, die gerade im Verblassen der ursprünglichen Hintergründe ihre Wirkmacht in breiter diskursiver Streuung entfaltet. Dabei reichen die vielfältigen Fortschreibungen und Transformationen weit über das frühe Mittelalter und die klassische Theologie hinaus und zeigen in der Moderne und Postmoderne verstärkt nur noch Allusionen auf die ursprünglich religiöse Ordnungsphantasie. So werden die Todsünden zu einem intermedialen Fundus für ethische und politische Reflexionen, ästhetische Transformationen und künstlerische Experimente. Der Band versammelt Studien, die sich aus literatur-, medien- und kulturwissenschaftlicher Perspektive sowohl den einzelnen Todsünden superbia, invidia, ira, acedia, avaritia, gula, luxuria als auch dem Septenar insgesamt widmen