Qualität und Nutzen - Über den Gebrauch von Zeit-Wert-Funktionen zur Integration qualitäts- und zeit-flexibler Aspekte in einer dynamischen Echtzeit-Einplanungsumgebung

Scheduling methodologies for real-time applications have been of keen interest to diverse research communities for several decades. Depending on the application area, algorithms have been developed that are tailored to specific requirements with respect to both the individual components of which an application is made up and the computational platform on which it is to be executed. Many real-time scheduling algorithms base their decisions solely or partly on timing constraints expressed by deadlines which must be met even under worst-case conditions. The increasing complexity of computing hardware means that worst-case execution time analysis becomes increasingly pessimistic. Scheduling hard real-time computations according to their worst-case execution times (which is common practice) will thus result, on average, in an increasing amount of spare capacity. The main goal of flexible real-time scheduling is to exploit this otherwise wasted capacity. Flexible scheduling schemes have been proposed to increase the ability of a real-time system to adapt to changing requirements and nondeterminism in the application behaviour. These models can be categorised as those whose source of flexibility is the quality of computations and those which are flexible regarding their timing constraints. This work describes a novel model which allows to specify both flexible timing constraints and quality profiles for an application. Furthermore, it demonstrates the applicability of this specification method to real-world examples and suggests a set of feasible scheduling algorithms for the proposed problem class.Einplanungsverfahren für Echtzeitanwendungen stehen seit Jahrzehnten im Interesse verschiedener Forschungsgruppen. Abhängig vom Anwendungsgebiet wurden Algorithmen entwickelt, welche an die spezifischen Anforderungen sowohl hinsichtlich der einzelnen Komponenten, aus welchen eine Anwendung besteht, als auch an die Rechnerplattform, auf der diese ausgeführt werden sollen, angepasst sind. Viele Echtzeit-Einplanungsverfahren gründen ihre Entscheidungen ausschließlich oder teilweise auf Zeitbedingungen, welche auch bei Auftreten maximaler Ausführungszeiten eingehalten werden müssen. Die zunehmende Komplexität von Rechner-Hardware bedeutet, dass die Worst-Case-Analyse in steigendem Maße pessimistisch wird. Die Einplanung harter Echtzeit-Berechnungen anhand ihrer maximalen Ausführungszeiten (was die gängige Praxis darstellt) resultiert daher im Regelfall in einer frei verfügbaren Rechenkapazität in steigender Höhe. Das Hauptziel flexibler Echtzeit-Einplanungsverfahren ist es, diese ansonsten verschwendete Kapazität auszunutzen. Flexible Einplanungsverfahren wurden vorgeschlagen, welche die Fähigkeit eines Echtzeitsystems erhöhen, sich an veränderte Anforderungen und Nichtdeterminismus im Verhalten der Anwendung anzupassen. Diese Modelle können unterteilt werden in solche, deren Quelle der Flexibilität die Qualität der Berechnungen ist, und jene, welche flexibel hinsichtlich ihrer Zeitbedingungen sind. Diese Arbeit beschreibt ein neuartiges Modell, welches es erlaubt, sowohl flexible Zeitbedingungen als auch Qualitätsprofile für eine Anwendung anzugeben. Außerdem demonstriert sie die Anwendbarkeit dieser Spezifikationsmethode auf reale Beispiele und schlägt eine Reihe von Einplanungsalgorithmen für die vorgestellte Problemklasse vor

Specification and Simulation of Scheduling Problems With the Multi-Purpose Framework PASCHA

In this article, we present a novel framework for the specification and simulation of scheduling algorithms. The advantages of the toolkit compared to other similar simulation systems are primarily due to the flexibility of the underlying system model. Our abstract model can handle both, but is not limited to, classic realtime tasks with soft, firm, or hard deadlines and anytime tasks whose contribution to the application varies according to the available CPU time. The simulation environment can handle mixed sets of hard realtime, soft realtime, and anytime methods, provided that a suitable scheduler has been devised for a particular problem class. A suite of integrated tools makes it easy to implement scheduling algorithms, to construct applications, and to simulate these applications together with the scheduling algorithm. We consider this framework to be a very useful contribution to the community of task scheduling research.

Protein tyrosine phosphatase non-receptor type 22 modulates colitis in a microbiota-dependent manner

The gut microbiota is crucial for our health, and well-balanced interactions between the host's immune system and the microbiota are essential to prevent chronic intestinal inflammation, as observed in inflammatory bowel diseases (IBD). A variant in protein tyrosine phosphatase non-receptor type 22 (PTPN22) is associated with reduced risk of developing IBD, but promotes the onset of autoimmune disorders. While the role of PTPN22 in modulating molecular pathways involved in IBD pathogenesis is well studied, its impact on shaping the intestinal microbiota has not been addressed in depth. Here, we demonstrate that mice carrying the PTPN22 variant (619W mice) were protected from acute dextran sulfate sodium (DSS) colitis, but suffered from pronounced inflammation upon chronic DSS treatment. The basal microbiota composition was distinct between genotypes, and DSS-induced dysbiosis was milder in 619W mice than in WT littermates. Transfer of microbiota from 619W mice after the first DSS cycle into treatment-naive 619W mice promoted colitis, indicating that changes in microbial composition enhanced chronic colitis in those animals. This indicates that presence of the PTPN22 variant affects intestinal inflammation by modulating the host's response to the intestinal microbiota

Protein tyrosine phosphatase non-receptor type 22 modulates colitis in a microbiota-dependent manner

ISSN:1558-8238ISSN:0021-973

TiO₂ nanoparticles abrogate the protective effect of the Crohn’s disease-associated variation within the PTPN22 gene locus

Objective: Inflammatory bowel disease (IBD) is a multifactorial condition driven by genetic and environmental risk factors. A genetic variation in the protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene has been associated with autoimmune disorders while protecting from the IBD subtype Crohn’s disease. Mice expressing the murine orthologous PTPN22-R619W variant are protected from intestinal inflammation in the model of acute dextran sodium sulfate (DSS)-induced colitis. We previously identified food-grade titanium dioxide (TiO₂, E171) as a neglected IBD risk factor. Here, we investigate the interplay of the PTPN22 variant and TiO₂-mediated effects during IBD pathogenesis. Design: Acute DSS colitis was induced in wild-type and PTPN22 variant mice (PTPN22-R619W) and animals were treated with TiO₂ nanoparticles during colitis induction. Disease-triggering mechanisms were investigated using bulk and single-cell RNA sequencing.ResultsIn mice, administration of TiO₂ nanoparticles abrogated the protective effect of the variant, rendering PTPN22-R619W mice susceptible to DSS colitis. In early disease, cytotoxic CD8⁺ T-cells were found to be reduced in the lamina propria of PTPN22-R619W mice, an effect reversed by TiO₂ administration. Normalisation of T-cell populations correlated with increased Ifng expression and, at a later stage of disease, the promoted prevalence of proinflammatory macrophages that triggered severe intestinal inflammation. Conclusion: Our findings indicate that the consumption of TiO₂ nanoparticles might have adverse effects on the gastrointestinal health of individuals carrying the PTPN22 variant. This demonstrates that environmental factors interact with genetic risk variants and can reverse a protective mechanism into a disease-promoting effect