| 1. |
- Axer, Philip, et al.
(författare)
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Building Timing Predictable Embedded Systems
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A large class of embedded systems is distinguished from general purpose computing systems by the need to satisfy strict requirements on timing, often under constraints on available resources. Predictable system design is concerned with the challenge of building systems for which timing requirements can be guaranteed a priori. Perhaps paradoxically, this problem has become more difficult by the introduction of performance-enhancing architectural elements, such as caches, pipelines, and multithreading, which introduce a large degree of nondeterminism and make guarantees harder to provide. The intention of this paper is to summarize current state-of-the-art in research concerning how to build predictable yet performant systems. We suggest precise definitions for the concept of “predictability”, and present predictability concerns at different abstractions levels in embedded software design. First, we consider timing predictability of processor instruction sets. Thereafter, We consider how programming languages can be equipped with predictable timing semantics, covering both a language-based approach based on the synchronous paradigm, as well as an environment that provides timing semantics for a mainstream programming language (in this case C). We present techniques for achieving timing predictability on multicores. Finally we discuss how to handle predictability at the level of networked embedded systems, where randomly occurring errors must be considered.
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| 2. |
- Altmeyer, Sebastian, et al.
(författare)
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Parametric timing analysis for complex architectures
- 2008
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Ingår i: Proceedings - 14th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2008. - 9780769533490 ; , s. 367-376
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Konferensbidrag (refereegranskat)abstract
- Hard real-time systems have stringent timing constraints expressed in units of time. To ensure that a task finishes within its time-frame, the designer of such a system must be able to derive upper bounds on the task's worst-case execution time (WCET). To compute such upper bounds, timing analyses are used. These analyses require that information such as bounds on the maximum numbers of loop iterations are known statically, i.e. during design time. Parametric timing analysis softens these requirements: it yields symbolic formulas instead of single numeric values representing the upper bound on the task's execution time.In this paper, we present a new parametric timing analysis that is able to derive safe and precise results. Our method determines what the parameters of the program are, constructs parametric loop bounds, takes processor behaviour into account and attains a formula automatically. In the end, we present tests to show that the precision and runtime of our analysis are very close to those of numeric timing analysis.
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| 3. |
- Brakebusch, Cord, et al.
(författare)
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Beta1 integrin is not essential for hematopoiesis but is necessary for the T cell-dependent IgM antibody response.
- 2002
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Ingår i: Immunity. - 1074-7613. ; 16:3, s. 465-477
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Tidskriftsartikel (refereegranskat)abstract
- Several experimental evidences suggested that beta1 integrin-mediated adhesion of hematopoietic stem cells (HSC) is important for their function in the bone marrow (BM). Using induced deletion of the beta1 integrin gene restricted to the hematopoietic system, we show that beta1 integrin is not essential for HSC retention in the BM, hematopoiesis, and trafficking of lymphocytes. However, immunization with a T cell-dependent antigen resulted in virtually no IgM production and an increased secretion of IgG in mutant mice, while the response to a T cell-independent type 2 antigen showed decreases in both IgM and IgG. These data suggest that beta1 integrins are necessary for the primary IgM antibody response.
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| 4. |
- Caspi, Paul, et al.
(författare)
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Guidelines for a curriculum on embedded software and systems
- 2005
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Ingår i: ACM Transactions on Embedded Computing Systems. - : ACM Press. - 1539-9087 .- 1558-3465. ; 4:3, s. 587-611
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Tidskriftsartikel (refereegranskat)abstract
- The design of embedded real-time systems requires skills from multiple specific disciplines, including, but not limited to, control, computer science, and electronics. This often involves experts from differing backgrounds, who do not recognize that they address similar, if not identical, issues from complementary angles. Design methodologies are lacking in rigor and discipline so that demonstrating correctness of an embedded design, if at all possible, is a very expensive proposition that may delay significantly the introduction of a critical product. While the economic importance of embedded systems is widely acknowledged, academia has not paid enough attention to the education of a community of high-quality embedded system designers, an obvious difficulty being the need of interdisciplinarity in a period where specialization has been the target of most education systems. This paper presents the reflections that took place in the European Network of Excellence Artist leading us to propose principles and structured contents for building curricula on embedded software and systems.
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| 5. |
- Dours-Zimmermann, Maria T., et al.
(författare)
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Versican V2 Assembles the Extracellular Matrix Surrounding the Nodes of Ranvier in the CNS
- 2009
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 29:24, s. 7731-7742
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Tidskriftsartikel (refereegranskat)abstract
- The CNS-restricted versican splice-variant V2 is a large chondroitin sulfate proteoglycan incorporated in the extracellular matrix surrounding myelinated fibers and particularly accumulating at nodes of Ranvier. In vitro, it is a potent inhibitor of axonal growth and therefore considered to participate in the reduction of structural plasticity connected to myelination. To study the role of versican V2 during postnatal development, we designed a novel isoform-specific gene inactivation approach circumventing early embryonic lethality of the complete knock-out and preventing compensation by the remaining versican splice variants. These mice are viable and fertile; however, they display major molecular alterations at the nodes of Ranvier. While the clustering of nodal sodium channels and paranodal structures appear in versican V2-deficient mice unaffected, the formation of the extracellular matrix surrounding the nodes is largely impaired. The conjoint loss of tenascin-R and phosphacan from the perinodal matrix provide strong evidence that versican V2, possibly controlled by a nodal receptor, organizes the extracellular matrix assembly in vivo.
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| 6. |
- Ermedahl, Andreas
(författare)
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A Modular Tool Architecture for Worst-Case Execution Time Analysis
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estimations of the Worst-Case Execution Time (WCET) are required in providing guarantees for timing of programs used in computer controlled products and other real-time computer systems. To derive program WCET estimates, both the properties of the software and the hardware must be considered. The traditional method to obtain WCET estimates is to test the system and measure the execution time. This is labour-intensive and error-prone work, which unfortunately cannot guarantee that the worst case is actually found. Static WCET analyses, on the other hand, are capable of generating safe WCET estimates without actually running the program. Such analyses use models of program flow and hardware timing to generate WCET estimates. This thesis includes several contributions to the state-of-the-art in static WCET analysis: (1) A tool architecture for static WCET analysis, which divides the WCET analysis into several steps, each with well-defined interfaces. This allows independent replacement of the modules implementing the different steps, which makes it easy to customize a WCET tool for particular target hardware and analysis needs. (2) A representation for the possible executions of a program. Compared to previous approaches, our representation extends the type of program flow information possible to express and handle in WCET analysis. (3) A calculation method which explicitly extracts a longest program execution path. The method is more efficient than previously presented path-based methods, with a computational complexity close to linear in the size of the program. (4) A calculation method using integer linear programming or constraint programming techniques for calculating the WCET estimate. The method extends the power of such calculation methods to handle new types of flow and timing information. (5) A calculation method that first uses flow information to divide the program into smaller parts, then calculates individual WCET estimates for these parts, and finally combines these into an overall program WCET. This novel approach avoids potential complexity problems, while still providing high precision WCET estimates. We have additionally implemented a prototype WCET analysis tool based on the proposed architecture. This tool is used for extensive evaluation of the precision and performance of our proposed methods. The results indicate that it is possible to perform WCET analysis in a modular fashion, and that this analysis produces high quality WCET estimates.
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| 7. |
- Genius, Daniela, et al.
(författare)
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Java and CoSy Technology for Embedded Systems : the JOSES Project
- 1999
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Konferensbidrag (refereegranskat)abstract
- Even though there is a growing interest in Java-based embedded computing, compilers have to solve several problems before they can produce high performance Java code. On the one hand, Java`s advanced features, e.g. calls of virtual methods, need to be optimized with appropriate inter-class techniques. Additionally, Java`s memory management requires fast garbage collection observing real-time deadlines. On the other hand, new hardware trends create problems: heterogeneous parallel embedded systems require new techniques for performance optimization, and cache storage needs to be allocated by the compiler in order to exploit the speed of new processors. To meet these requirements, the EU long-term research project JOSES (Java and CoSy technology for Embedded Systems) has been initiated. Its mission is to create a Java-based European technology for heterogeneous embedded systems, including an optimizing Java compiler environment producing high-performance native code. JOSES will exploit the European product-quality compiler framework CoSy, marketed by ACE. This component-based technology allows re-use of existing compiler engines and employs generator technology wherever possible.
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Ma, Li-Jun, et al.
(författare)
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Genomic analysis of the basal lineage fungus Rhizopus oryzae reveals a whole-genome duplication.
- 2009
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 5:7, s. e1000549-
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Tidskriftsartikel (refereegranskat)abstract
- Rhizopus oryzae is the primary cause of mucormycosis, an emerging, life-threatening infection characterized by rapid angioinvasive growth with an overall mortality rate that exceeds 50%. As a representative of the paraphyletic basal group of the fungal kingdom called "zygomycetes," R. oryzae is also used as a model to study fungal evolution. Here we report the genome sequence of R. oryzae strain 99-880, isolated from a fatal case of mucormycosis. The highly repetitive 45.3 Mb genome assembly contains abundant transposable elements (TEs), comprising approximately 20% of the genome. We predicted 13,895 protein-coding genes not overlapping TEs, many of which are paralogous gene pairs. The order and genomic arrangement of the duplicated gene pairs and their common phylogenetic origin provide evidence for an ancestral whole-genome duplication (WGD) event. The WGD resulted in the duplication of nearly all subunits of the protein complexes associated with respiratory electron transport chains, the V-ATPase, and the ubiquitin-proteasome systems. The WGD, together with recent gene duplications, resulted in the expansion of multiple gene families related to cell growth and signal transduction, as well as secreted aspartic protease and subtilase protein families, which are known fungal virulence factors. The duplication of the ergosterol biosynthetic pathway, especially the major azole target, lanosterol 14alpha-demethylase (ERG11), could contribute to the variable responses of R. oryzae to different azole drugs, including voriconazole and posaconazole. Expanded families of cell-wall synthesis enzymes, essential for fungal cell integrity but absent in mammalian hosts, reveal potential targets for novel and R. oryzae-specific diagnostic and therapeutic treatments.
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| 12. |
- Schindler, Birgit Karin, et al.
(författare)
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The European COPHES/DEMOCOPHES project: Towards transnational comparability and reliability of human biomonitoring results.
- 2014
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Ingår i: International Journal of Hygiene and Environmental Health. - : Elsevier BV. - 1618-131X .- 1438-4639. ; 217:6, s. 653-661
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Tidskriftsartikel (refereegranskat)abstract
- COPHES/DEMOCOPHES has its origins in the European Environment and Health Action Plan of 2004 to "develop a coherent approach on human biomonitoring (HBM) in Europe". Within this twin-project it was targeted to collect specimens from 120 mother-child-pairs in each of the 17 participating European countries. These specimens were investigated for six biomarkers (mercury in hair; creatinine, cotinine, cadmium, phthalate metabolites and bisphenol A in urine). The results for mercury in hair are described in a separate paper. Each participating member state was requested to contract laboratories, for capacity building reasons ideally within its borders, carrying out the chemical analyses. To ensure comparability of analytical data a Quality Assurance Unit (QAU) was established which provided the participating laboratories with standard operating procedures (SOP) and with control material. This material was specially prepared from native, non-spiked, pooled urine samples and was tested for homogeneity and stability. Four external quality assessment exercises were carried out. Highly esteemed laboratories from all over the world served as reference laboratories. Web conferences after each external quality assessment exercise functioned as a new and effective tool to improve analytical performance, to build capacity and to educate less experienced laboratories. Of the 38 laboratories participating in the quality assurance exercises 14 laboratories qualified for cadmium, 14 for creatinine, 9 for cotinine, 7 for phthalate metabolites and 5 for bisphenol A in urine. In the last of the four external quality assessment exercises the laboratories that qualified for DEMOCOPHES performed the determinations in urine with relative standard deviations (low/high concentration) of 18.0/2.1% for cotinine, 14.8/5.1% for cadmium, 4.7/3.4% for creatinine. Relative standard deviations for the newly emerging biomarkers were higher, with values between 13.5 and 20.5% for bisphenol A and between 18.9 and 45.3% for the phthalate metabolites. Plausibility control of the HBM results of all participating countries disclosed analytical shortcomings in the determination of Cd when using certain ICP/MS methods. Results were corrected by reanalyzes. The COPHES/DEMOCOPHES project for the first time succeeded in performing a harmonized pan-European HBM project. All data raised have to be regarded as utmost reliable according to the highest international state of the art, since highly renowned laboratories functioned as reference laboratories. The procedure described here, that has shown its success, can be used as a blueprint for future transnational, multicentre HBM projects.
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| 13. |
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| 14. |
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| 15. |
- Wilhelm, Reinhard, et al.
(författare)
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The worst-case execution-time problem—overview of methods and survey of tools
- 2008
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Ingår i: ACM Transactions on Embedded Computing Systems. - : Association for Computing Machinery (ACM). - 1539-9087 .- 1558-3465. ; 7:3, s. article nr: 36-
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Tidskriftsartikel (refereegranskat)abstract
- The determination of upper bounds on execution times, commonly called worst-case execution times (WCETs), is a necessary step in the development and validation process for hard real-time systems. This problem is hard if the underlying processor architecture has components, such as caches, pipelines, branch prediction, and other speculative components. This article describes different approaches to this problem and surveys several commercially available tools(1) and research prototypes.
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