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  • 51.
    Carlson, Trevor E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Tran, Kim-Anh
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Jimborean, Alexandra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Koukos, Konstantinos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Själander, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Transcending hardware limits with software out-of-order processing2017In: IEEE Computer Architecture Letters, ISSN 1556-6056, Vol. 16, no 2, p. 162-165Article in journal (Refereed)
  • 52.
    Carlsson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    Mattsson, Moa
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    The MaRiQ model: A quantitative approach to risk management2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In recent years, cyber attacks and data fraud have become major issues to companies, businesses and nation states alike. The need for more accurate and reliable risk management models is therefore substantial.

    Today, cybersecurity risk management is often carried out on a qualitative basis, where risks are evaluated to a predefined set of categories such as low, medium or high. This thesis aims to challenge that practice, by presenting a model that quantitatively assesses risks - therefore named MaRiQ (Manage Risks Quantitatively).

    MaRiQ was developed based on collected requirements and contemporary literature on quantitative risk management. The model consists of a clearly defined flowchart and a supporting tool created in Excel. To generate scientifically validated results, MaRiQ makes use of a number of statistical techniques and mathematical functions, such as Monte Carlo simulations and probability distributions.

    To evaluate whether our developed model really was an improvement compared to current qualitative processes, we conducted a workshop at the end of the project. The organization that tested MaRiQexperienced the model to be useful and that it fulfilled most of their needs.

    Our results indicate that risk management within cybersecurity can and should be performed using more quantitative approaches than what is praxis today. Even though there are several potential developments to be made, MaRiQ demonstrates the possible advantages of transitioning from qualitative to quantitative risk management processes.

  • 53.
    Ceballos, Germán
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    How to make tasks faster: Revealing the complex interactions of tasks in the memory system2017In: Proc. Companion 8th ACM International Conference on Systems, Programming, Languages, and Applications: Software for Humanity, New York: ACM Press, 2017, p. 1-3Conference paper (Refereed)
  • 54.
    Ceballos, Germán
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Modeling the interactions between tasks and the memory system2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Making computer systems more energy efficient while obtaining the maximum performance possible is key for future developments in engineering, medicine, entertainment, etc. However it has become a difficult task due to the increasing complexity of hardware and software, and their interactions. For example, developers have to deal with deep, multi-level cache hierarchies on modern CPUs, and keep busy thousands of cores in GPUs, which makes the programming process more difficult.

    To simplify this task, new abstractions and programming models are becoming popular. Their goal is to make applications more scalable and efficient, while still providing the flexibility and portability of old, widely adopted models. One example of this is task-based programming, where simple independent tasks (functions) are delegated to a runtime system which orchestrates their execution. This approach has been successful because the runtime can automatically distribute work across hardware cores and has the potential to minimize data movement and placement (e.g., being aware of the cache hierarchy).

    To build better runtime systems, it is crucial to understand bottlenecks in the performance of current and future multicore systems. In this thesis, we provide fast, accurate and mathematically-sound models and techniques to understand the execution of task-based applications concerning three key aspects: memory behavior (data locality), scheduling, and performance. With these methods, we lay the groundwork for improving runtime system, providing insight into the interplay between the schedule's behavior, data reuse through the cache hierarchy, and the resulting performance.

    List of papers
    1. Shared Resource Sensitivity in Task-Based Runtime Systems
    Open this publication in new window or tab >>Shared Resource Sensitivity in Task-Based Runtime Systems
    2013 (English)In: Proc. 6th Swedish Workshop on Multi-Core Computing, Halmstad University Press, 2013Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Halmstad University Press, 2013
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-212780 (URN)
    Conference
    MCC13, November 25–26, Halmstad, Sweden
    Projects
    Resource Sharing ModelingUPMARC
    Funder
    Swedish Research Council
    Available from: 2013-12-13 Created: 2013-12-13 Last updated: 2018-11-16Bibliographically approved
    2. Formalizing data locality in task parallel applications
    Open this publication in new window or tab >>Formalizing data locality in task parallel applications
    2016 (English)In: Algorithms and Architectures for Parallel Processing, Springer, 2016, p. 43-61Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Springer, 2016
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 10049
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-310341 (URN)10.1007/978-3-319-49956-7_4 (DOI)000389797000004 ()978-3-319-49955-0 (ISBN)
    Conference
    ICA3PP 2016, December 14–16, Granada, Spain
    Projects
    UPMARCResource Sharing Modeling
    Funder
    Swedish Foundation for Strategic Research , FFL12-0051
    Available from: 2016-11-19 Created: 2016-12-14 Last updated: 2018-11-16Bibliographically approved
    3. TaskInsight: Understanding task schedules effects on memory and performance
    Open this publication in new window or tab >>TaskInsight: Understanding task schedules effects on memory and performance
    2017 (English)In: Proc. 8th International Workshop on Programming Models and Applications for Multicores and Manycores, New York: ACM Press, 2017, p. 11-20Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    New York: ACM Press, 2017
    National Category
    Computer Engineering
    Identifiers
    urn:nbn:se:uu:diva-315033 (URN)10.1145/3026937.3026943 (DOI)978-1-4503-4883-6 (ISBN)
    Conference
    PMAM 2017, February 4–8, Austin, TX
    Projects
    UPMARCResource Sharing Modeling
    Funder
    Swedish Research CouncilSwedish Foundation for Strategic Research , FFL12-0051EU, Horizon 2020, 687698
    Available from: 2017-02-04 Created: 2017-02-08 Last updated: 2018-11-16Bibliographically approved
    4. Analyzing performance variation of task schedulers with TaskInsight
    Open this publication in new window or tab >>Analyzing performance variation of task schedulers with TaskInsight
    2018 (English)In: Parallel Computing, ISSN 0167-8191, E-ISSN 1872-7336, Vol. 75, p. 11-27Article in journal (Refereed) Published
    National Category
    Computer Engineering
    Identifiers
    urn:nbn:se:uu:diva-340202 (URN)10.1016/j.parco.2018.02.003 (DOI)000433655700002 ()
    Projects
    UPMARCResource Sharing Modeling
    Funder
    Swedish Research Council, FFL12-0051Swedish Foundation for Strategic Research , FFL12-0051
    Available from: 2018-02-22 Created: 2018-01-26 Last updated: 2018-11-16Bibliographically approved
  • 55.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Shared Resource Sensitivity in Task-Based Runtime Systems2013In: Proc. 6th Swedish Workshop on Multi-Core Computing, Halmstad University Press, 2013Conference paper (Refereed)
  • 56.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Tail-PASS: Resource-based Cache Management for Tiled Graphics Rendering Hardware2018In: Proc. 16th International Conference on Parallel and Distributed Processing with Applications, IEEE, 2018, p. 55-63Conference paper (Refereed)
    Abstract [en]

    Modern graphics rendering is a very expensive process and can account for 60% of the battery consumption on current games. Much of the cost comes from the high memory bandwidth of rendering complex graphics. To render a frame, multiple smaller rendering passes called scenes are executed, with each one tiled for parallel execution. The data for each scene comes from hundreds of software resources (textures). We observe that each frame can consume up to 1000s of MB of data, but that over 75% of the graphics memory accesses are to the top-10 resources, and that bypassing the remaining infrequently accessed (tail) resources reduces cache pollution. Bypassing the tail can save up to 35% of the main memory traffic over resource-oblivious replacement policies and cache management techniques. In this paper, we propose Tail-PASS, a cache management technique that detects the most accessed resources at runtime, learns if it is worth bypassing the least accessed ones, and then dynamically enables/disables bypassing to reduce cache pollution on a per-scene basis. Overall, we see an average reduction in bandwidth-per-frame of 22% (up to 46%) by bypassing all but the top-10 resources and an 11% (up to 44%) reduction if only the top-2 resources are cached.

  • 57.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Understanding the interplay between task scheduling, memory and performance2017In: Proc. Companion 8th ACM International Conference on Systems, Programming, Languages, and Applications: Software for Humanity, New York: ACM Press, 2017, p. 21-23Conference paper (Refereed)
  • 58.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hugo, Andra
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Exploring scheduling effects on task performance with TaskInsight2017In: Supercomputing frontiers and innovations, ISSN 2214-3270, E-ISSN 2313-8734, Vol. 4, no 3, p. 91-98Article in journal (Refereed)
  • 59.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Sembrant, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Carlson, Trevor E.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Analyzing Graphics Workloads on Tile-based GPUs2017In: Proc. 20th International Symposium on Workload Characterization, IEEE, 2017, p. 108-109Conference paper (Refereed)
  • 60.
    Ceballos, Germán
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Sembrant, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Carlson, Trevor E.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Behind the Scenes: Memory Analysis of Graphical Workloads on Tile-based GPUs2018In: Proc. International Symposium on Performance Analysis of Systems and Software: ISPASS 2018, IEEE Computer Society, 2018, p. 1-11Conference paper (Refereed)
  • 61.
    Chan, Aaron
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Mazorchuk, Volodymyr
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Diagrams and discrete extensions for finitary 2-representations2019In: Mathematical proceedings of the Cambridge Philosophical Society (Print), ISSN 0305-0041, E-ISSN 1469-8064, Vol. 166, no 2, p. 325-352Article in journal (Refereed)
    Abstract [en]

    In this paper we introduce and investigate the notions of diagrams and discrete extensions in the study of finitary 2-representations of finitary 2-categories.

  • 62.
    Chen, Taolue
    et al.
    University of Oxford.
    Chilton, Chris
    University of Oxford.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kwiatkowska, Marta
    University of Oxford.
    A Compositional Specification Theory for Component Behaviours2012Report (Other academic)
  • 63.
    Chen, Weili
    et al.
    Sun Yat-sen University, Guangzhou, China.
    Zheng, Zibin
    Sun Yat-sen University, Guangzhou, China.
    Jiahui, Cui
    Sun Yat-sen University, Guangzhou, China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zheng, Peilin
    Sun Yat-sen University, Guangzhou, China.
    Zhou, Yuren
    Sun Yat-sen University, Guangzhou, China.
    Detecting Ponzi Schemes on Ethereum: Towards Healthier Blockchain Technology2018In: WWW '18: Proceedings of the 2018 World Wide Web Conference, ACM Digital Library, 2018, p. 1409-1418Conference paper (Refereed)
    Abstract [en]

    Blockchain technology becomes increasingly popular. It also attracts scams, for example, Ponzi scheme, a classic fraud, has been found making a notable amount of money on Blockchain, which has a very negative impact. To help dealing with this issue, this paper proposes an approach to detect Ponzi schemes on blockchain by using data mining and machine learning methods. By verifying smart contracts on Ethereum, we first extract features from user accounts and operation codes of the smart contracts and then build a classification model to detect latent Ponzi schemes implemented as smart contracts. The experimental results show that the proposed approach can achieve high accuracy for practical use. More importantly, the approach can be used to detect Ponzi schemes even at the moment of its creation. By using the proposed approach, we estimate that there are more than 400 Ponzi schemes running on Ethereum. Based on these results, we propose to build a uniform platform to evaluate and monitor every created smart contract for early warning of scams.

  • 64.
    Chen, Weili
    et al.
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Zheng, Zibin
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Ngai, Edith
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Zheng, Peilin
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Zhou, Yuren
    Sun Yat Sen Univ, Sch Data & Comp Sci, Guangzhou 510006, Guangdong, Peoples R China;Sun Yat Sen Univ, Natl Engn Res Ctr Digital Life, Guangzhou 510006, Guangdong, Peoples R China.
    Exploiting Blockchain Data to Detect Smart Ponzi Schemes on Ethereum2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 37575-37586Article in journal (Refereed)
    Abstract [en]

    Blockchain technology becomes increasingly popular. It also attracts scams, for example, a Ponzi scheme, a classic fraud, has been found making a notable amount of money on Blockchain, which has a very negative impact. To help to deal with this issue and to provide reusable research data sets for future research, this paper collects real-world samples and proposes an approach to detect Ponzi schemes implemented as smart contracts (i.e., smart Ponzi schemes) on the blockchain. First, 200 smart Ponzi schemes are obtained by manually checking more than 3,000 open source smart contracts on the Ethereum platform. Then, two kinds of features are extracted from the transaction history and operation codes of the smart contracts. Finally, a classification model is presented to detect smart Ponzi schemes. The extensive experiments show that the proposed model performs better than many traditional classification models and can achieve high accuracy for practical use. By using the proposed approach, we estimate that there are more than 500 smart Ponzi schemes running on Ethereum. Based on these results, we propose to build a uniform platform to evaluate and monitor every created smart contract for early warning of scams.

  • 65.
    Chilton, Chris
    et al.
    University of Oxford.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kwiatkowska, Marta
    University of Oxford.
    An Algebraic Theory of Interface Automata2013Report (Other academic)
  • 66.
    Chilton, Chris
    et al.
    University of Oxford.
    Jonsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kwiatkowska, Marta
    University of Oxford.
    Assume-Guarantee Reasoning for Safe Component Behaviours2012In: Proc. FACS: Formal Aspects of Component Software, 9th Int. Symp. / [ed] Corina S. Pasareanu, Gwen Salaün, Springer, 2012, p. 92-109Conference paper (Refereed)
    Abstract [en]

    We formulate a sound and complete assume-guarantee framework for reasoning compositionally about safety properties of component behaviours. The specification of a component, which constrains the temporal ordering of input and output interactions with the environment, is expressed in terms of two prefix-closed sets of traces: an assumption and guarantee. The framework supports dynamic reasoning about components and specifications, and includes rules for parallel composition, logical conjunction corresponding to independent development, and quotient for incremental synthesis. Practical applicability of the framework is demonstrated by considering a simple printing example.

  • 67.
    Clebsch, Sylvan
    et al.
    Microsoft Research, UK.
    Franco, Juliana
    Imperial College London, UK.
    Drossopoulou, Sophia
    Imperial College London, UK.
    Yang, Albert Mingkun
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Wrigstad, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Vitek, Jan
    Northeastern University, USA.
    Orca: GC and Type System Co-design for Actor Languages2017In: Proceedings of the ACM on Programming Languages, ISSN 2475-1421, Vol. 1, no OOPSLA, p. 1-28, article id 72Article in journal (Refereed)
    Abstract [en]

    ORCA is a concurrent and parallel garbage collector for actor programs, which does not require any STW steps, or synchronization mechanisms, and that has been designed to support zero-copy message passing and sharing of mutable data. ORCA is part of a runtime for actor-based languages, which was co-designed with the Pony programming language, and in particular, with its data race free type system. By co-designing an actor language with its runtime, it was possible to exploit certain language properties in order to optimize performance of garbage collection. Namely, ORCA relies on the guarantees of absence of race conditions in order to avoid read/write barriers, and it leverages the actor message passing, for synchronization among actors.

    In this paper we briefly describe Pony and its type system. We use pseudo-code in order to introduce how ORCA allocates and deallocates objects, how it shares mutable data without requiring barriers upon data mutation, and how can immutability be used to further optimize garbage collection. Moreover, we discuss the advantages of co-designing an actor language with its runtime, and we demonstrate that ORCA can be implemented in a performant and scalable way through a set of micro-benchmarks, including a comparison with other well-known collectors.

  • 68.
    Cyriac, Aiswarya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gastin, Paul
    LSV, ENS Cachan.
    Reasoning about distributed systems: WYSIWYG2014Conference paper (Refereed)
  • 69.
    Cyriac, Aiswarya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gastin, Paul
    LSV, ENS Cachan.
    Narayan Kumar, K.
    Chennai Mathematical Institute.
    Controllers for the Verification of Communicating Multi-Pushdown Systems2014Conference paper (Refereed)
  • 70.
    Cyriac, Aiswarya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Gastin, Paul
    Narayan Kumar, K.
    Verifying Communicating Multi-pushdown Systems via Split-Width2014In: Automated Technology for Verification and Analysis, 2014, p. 1-17Conference paper (Refereed)
    Abstract [en]

    Communicating multi-pushdown systems model networks of multi-threaded recursive programs communicating via reliable FIFO channels. We extend the notion of split-width [8] to this setting, improving and simplifying the earlier definition. Split-width, while having the same power of clique-/tree-width, gives a divide-and-conquer technique to prove the bound of a class, thanks to the two basic operations, shuffle and merge, of the split-width algebra. We illustrate this technique on examples. We also obtain simple, uniform and optimal decision procedures for various verification problems parametrised by split-width.

  • 71.
    Dahlberg, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular Medicine.
    Genetic Cartography at Massively Parallel Scale2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Massively parallel sequencing (MPS) is revolutionizing genomics. In this work we use, refine, and develop new tools for the discipline.

    MPS has led to the discovery of multiple novel subtypes in Acute Lymphoblastic Leukemia (ALL). In Study I we screen for fusion genes in 134 pediatric ALL patients, including patients without an assigned subtype. In approximately 80% of these patients we detect novel or known fusion gene families, most of which display distinct methylation and expression patterns. This shows the potential for improvements in the clinical stratification of ALL. Large sample sizes are important to detect recurrent somatic variation. In Study II we investigate if a non-index overlapping pooling schema can be used to increase sample size and detect somatic variation. We designed a schema for 172 ALL samples and show that it is possible to use this method to call somatic variants.

    Around the globe there are many ongoing and completed genome projects. In Study III we sequenced the genome of 1000 Swedes to create a reference data set for the Swedish population. We identified more than 10 million variants that were not present in publicly available databases, highlighting the need for population-specific resources. Data, and the tools developed during this study, have been made publicly available as a resource for genomics in Sweden and abroad.

    The increased amount of sequencing data has created a greater need for automation. In Study IV we present Arteria, a computational automation system for sequencing core facilities. This system has been adopted by multiple facilities and has been used to analyze thousands of samples. In Study V we developed CheckQC, a program that provides automated quality control of Illumina sequencing runs. These tools make scaling up MPS less labour intensive, a key to unlocking the full future potential of genomics.

    The tools, and data presented here are a valuable contribution to the scientific community. Collectively they showcase the power of MPS and genomics to bring about new knowledge of human health and disease.

    List of papers
    1. Transcriptome sequencing in pediatric acute lymphoblastic leukemia identifies fusion genes associated with distinct DNA methylation profiles
    Open this publication in new window or tab >>Transcriptome sequencing in pediatric acute lymphoblastic leukemia identifies fusion genes associated with distinct DNA methylation profiles
    Show others...
    2017 (English)In: Journal of Hematology & Oncology, ISSN 1756-8722, E-ISSN 1756-8722, Vol. 10, article id 148Article in journal (Refereed) Published
    Abstract [en]

    Background: Structural chromosomal rearrangements that lead to expressed fusion genes are a hallmark of acute lymphoblastic leukemia (ALL). In this study, we performed transcriptome sequencing of 134 primary ALL patient samples to comprehensively detect fusion transcripts. Methods: We combined fusion gene detection with genome-wide DNA methylation analysis, gene expression profiling, and targeted sequencing to determine molecular signatures of emerging ALL subtypes. Results: We identified 64 unique fusion events distributed among 80 individual patients, of which over 50% have not previously been reported in ALL. Although the majority of the fusion genes were found only in a single patient, we identified several recurrent fusion gene families defined by promiscuous fusion gene partners, such as ETV6, RUNX1, PAX5, and ZNF384, or recurrent fusion genes, such as DUX4-IGH. Our data show that patients harboring these fusion genes displayed characteristic genome-wide DNA methylation and gene expression signatures in addition to distinct patterns in single nucleotide variants and recurrent copy number alterations. Conclusion: Our study delineates the fusion gene landscape in pediatric ALL, including both known and novel fusion genes, and highlights fusion gene families with shared molecular etiologies, which may provide additional information for prognosis and therapeutic options in the future.

    Keywords
    Pediatric acute lymphoblastic leukemia, RNA sequencing, Fusion genes, BCP-ALL, T-ALL, Translocation
    National Category
    Cancer and Oncology Pediatrics
    Identifiers
    urn:nbn:se:uu:diva-332658 (URN)10.1186/s13045-017-0515-y (DOI)000408001300001 ()28806978 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research , RBc08-008Swedish Cancer Society, 130440, 160711Swedish Childhood Cancer Foundation, 11098Swedish Research Council, C0524801, 2016-03691_3
    Note

    De 2 sista författarna delar sistaförfattarskapet.

    Available from: 2017-10-31 Created: 2017-10-31 Last updated: 2018-08-27Bibliographically approved
    2. Identification of somatic variants by targeted sequencing of pooled cancer samples
    Open this publication in new window or tab >>Identification of somatic variants by targeted sequencing of pooled cancer samples
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical Genetics
    Research subject
    Medical Genetics
    Identifiers
    urn:nbn:se:uu:diva-269752 (URN)
    Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2018-08-27
    3. SweGen: a whole-genome data resource of genetic variability in a cross-section of the Swedish population
    Open this publication in new window or tab >>SweGen: a whole-genome data resource of genetic variability in a cross-section of the Swedish population
    Show others...
    2017 (English)In: European Journal of Human Genetics, ISSN 1018-4813, E-ISSN 1476-5438, Vol. 25, no 11, p. 1253-1260Article in journal (Refereed) Published
    Abstract [en]

    Here we describe the SweGen data set, a comprehensive map of genetic variation in the Swedish population. These data represent a basic resource for clinical genetics laboratories as well as for sequencing-based association studies by providing information on genetic variant frequencies in a cohort that is well matched to national patient cohorts. To select samples for this study, we first examined the genetic structure of the Swedish population using high-density SNP-array data from a nation-wide cohort of over 10 000 Swedish-born individuals included in the Swedish Twin Registry. A total of 1000 individuals, reflecting a cross-section of the population and capturing the main genetic structure, were selected for whole-genome sequencing. Analysis pipelines were developed for automated alignment, variant calling and quality control of the sequencing data. This resulted in a genome-wide collection of aggregated variant frequencies in the Swedish population that we have made available to the scientific community through the website https://swefreq.nbis.se. A total of 29.2 million single-nucleotide variants and 3.8 million indels were detected in the 1000 samples, with 9.9 million of these variants not present in current databases. Each sample contributed with an average of 7199 individual-specific variants. In addition, an average of 8645 larger structural variants (SVs) were detected per individual, and we demonstrate that the population frequencies of these SVs can be used for efficient filtering analyses. Finally, our results show that the genetic diversity within Sweden is substantial compared with the diversity among continental European populations, underscoring the relevance of establishing a local reference data set.

    Place, publisher, year, edition, pages
    NATURE PUBLISHING GROUP, 2017
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-337314 (URN)10.1038/ejhg.2017.130 (DOI)000412823800012 ()28832569 (PubMedID)
    Funder
    Science for Life Laboratory - a national resource center for high-throughput molecular bioscienceKnut and Alice Wallenberg Foundation, 2014.0272Swedish Research CouncilSwedish National Infrastructure for Computing (SNIC), sens2016003EU, European Research Council, 282330
    Available from: 2018-01-08 Created: 2018-01-08 Last updated: 2018-08-27Bibliographically approved
    4. Arteria: An automation system for a sequencing core facility
    Open this publication in new window or tab >>Arteria: An automation system for a sequencing core facility
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Bioinformatics (Computational Biology) Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-357972 (URN)
    Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2018-08-27
    5. CheckQC: Quick quality control of Illumina sequencing runs
    Open this publication in new window or tab >>CheckQC: Quick quality control of Illumina sequencing runs
    2018 (English)In: The Journal of Open Source Software, ISSN 2475-9066, Vol. 3, no 22, article id 556Article in journal (Refereed) Published
    Keywords
    bioinformatics, sequencing
    National Category
    Bioinformatics (Computational Biology)
    Research subject
    Bioinformatics
    Identifiers
    urn:nbn:se:uu:diva-349255 (URN)10.21105/joss.00556 (DOI)
    Available from: 2018-04-24 Created: 2018-04-24 Last updated: 2018-08-27Bibliographically approved
  • 72.
    Dahlberg, Johan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular Medicine. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Hermansson, Johan
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular Medicine.
    Sturlaugsson, Steinar
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular Medicine. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Smeds, Patrik
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Ladenvall, Claes
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Valls Guimera, Roman
    University of Melbourne Center for Cancer Research, University of Melbourne, Melbourne, Australia.
    Reisinger, Florian
    University of Melbourne Center for Cancer Research, University of Melbourne, Melbourne, Australia.
    Hofmann, Oliver
    University of Melbourne Center for Cancer Research, University of Melbourne, Melbourne, Australia.
    Larsson, Pontus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Molecular Medicine. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Arteria: An automation system for a sequencing core facilityManuscript (preprint) (Other academic)
  • 73.
    Daniels, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Professional Competencies for Real?: A Question about Identity!2016In: ITiCSE '16 Proceedings of the 2016 ACM Conference in Innovation and Technology in Computer Science Education, ACM Digital Library, 2016Conference paper (Other academic)
    Abstract [en]

    How students develop professional competencies has been an interest for me for decades. There are several aspects to this issue that I have addressed, e.g. what are professional competencies, how can their development of them be supported in educational settings, what motivates a student to put in an effort towards developing a competency, how can they be assessed, how can progression of professional competencies be handled in education curricula, and how can development of professional competencies be specified in a course description. These are among the more prominent issues that have been on my mind. In this work I have noticed a huge "gap" between how professional competencies are expressed as important learning outcomes of degree programs and the almost zero link to how this development should be done at the course instance level. This "gap" is frustrating for me and a source for thoughts regarding how to bridge that "gap". Work in our research group UpCERG (Uppsala Computing Education Research Group, www.it.uu.se/research/group/upcerg) has lately included studying issues related to identity, initially mostly the identity of different student cohorts, but now also that of teachers and education leaders. This research provides valuable insights towards causes for the "gap". That is, the slow closing of the "gap" can be understood by placing this in the context of the identity of the teachers (especially) and the students. It is how professional competencies are valued in relation to "pure" subject knowledge among these identities that provides severe obstacles to inclusion of development of professional competencies in a meaningful way at the course instance level. This is despite much of the previous work regarding issues related to developing professional competencies in educational settings, as those mentioned above.

  • 74.
    Davari, Mahdad
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Advances Towards Data-Race-Free Cache Coherence Through Data Classification2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Providing a consistent view of the shared memory based on precise and well-defined semantics—memory consistency model—has been an enabling factor in the widespread acceptance and commercial success of shared-memory architectures. Moreover, cache coherence protocols have been employed by the hardware to remove from the programmers the burden of dealing with the memory inconsistency that emerges in the presence of the private caches. The principle behind all such cache coherence protocols is to guarantee that consistent values are read from the private caches at all times.

    In its most stringent form, a cache coherence protocol eagerly enforces two invariants before each data modification: i) no other core has a copy of the data in its private caches, and ii) all other cores know where to receive the consistent data should they need the data later. Nevertheless, by partly transferring the responsibility for maintaining those invariants to the programmers, commercial multicores have adopted weaker memory consistency models, namely the Total Store Order (TSO), in order to optimize the performance for more common cases.

    Moreover, memory models with more relaxed invariants have been proposed based on the observation that more and more software is written in compliance with the Data-Race-Free (DRF) semantics. The semantics of DRF software can be leveraged by the hardware to infer when data in the private caches might be inconsistent. As a result, hardware ignores the inconsistent data and retrieves the consistent data from the shared memory. DRF semantics therefore removes from the hardware the burden of eagerly enforcing the strong consistency invariants before each data modification. Instead, consistency is guaranteed only when needed. This results in manifold optimizations, such as reducing the energy consumption and improving the performance and scalability. The efficiency of detecting and discarding the inconsistent data is an important factor affecting the efficiency of such coherence protocols. For instance, discarding the consistent data does not affect the correctness, but results in performance loss and increased energy consumption.

    In this thesis we show how data classification can be leveraged as an effective tool to simplify the cache coherence based on the DRF semantics. In particular, we introduce simple but efficient hardware-based private/shared data classification techniques that can be used to efficiently detect the inconsistent data, thus enabling low-overhead and scalable cache coherence solutions based on the DRF semantics.

    List of papers
    1. Hierarchical private/shared classification: The key to simple and efficient coherence for clustered cache hierarchies
    Open this publication in new window or tab >>Hierarchical private/shared classification: The key to simple and efficient coherence for clustered cache hierarchies
    2015 (English)In: Proc. 21st International Symposium on High Performance Computer Architecture, IEEE Computer Society Digital Library, 2015, p. 186-197Conference paper, Published paper (Refereed)
    Abstract [en]

    Hierarchical clustered cache designs are becoming an appealing alternative for multicores. Grouping cores and their caches in clusters reduces network congestion by localizing traffic among several hierarchical levels, potentially enabling much higher scalability. While such architectures can be formed recursively by replicating a base design pattern, keeping the whole hierarchy coherent requires more effort and consideration. The reason is that, in hierarchical coherence, even basic operations must be recursive. As a consequence, intermediate-level caches behave both as directories and as leaf caches. This leads to an explosion of states, protocol-races, and protocol complexity. While there have been previous efforts to extend directory-based coherence to hierarchical designs their increased complexity and verification cost is a serious impediment to their adoption. We aim to address these concerns by encapsulating all hierarchical complexity in a simple function: that of determining when a data block is shared entirely within a cluster (sub-tree of the hierarchy) and is private from the outside. This allows us to eliminate complex recursive operations that span the hierarchy and instead employ simple coherence mechanisms such as self-invalidation and write-through-now restricted to operate within the cluster where a data block is shared. We examine two inclusivity options and discuss the relation of our approach to the recently proposed Hierarchical-Race-Free (HRF) memory models. Finally, comparisons to a hierarchical directory-based MOESI, VIPS-M, and TokenCMP protocols show that, despite its simplicity our approach results in competitive performance and decreased network traffic.

    Place, publisher, year, edition, pages
    IEEE Computer Society Digital Library, 2015
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-265651 (URN)10.1109/HPCA.2015.7056032 (DOI)000380564900016 ()9781479989300 (ISBN)
    External cooperation:
    Conference
    HPCA 2015, February 7–11, Burlingame, CA
    Available from: 2015-02-11 Created: 2015-11-02 Last updated: 2017-04-22Bibliographically approved
    2. The effects of granularity and adaptivity on private/shared classification for coherence
    Open this publication in new window or tab >>The effects of granularity and adaptivity on private/shared classification for coherence
    2015 (English)In: ACM Transactions on Architecture and Code Optimization (TACO), ISSN 1544-3566, E-ISSN 1544-3973, Vol. 12, no 3, article id 26Article in journal (Refereed) Published
    Abstract [en]

    Classification of data into private and shared has proven to be a catalyst for techniques to reduce coherence cost, since private data can be taken out of coherence and resources can be concentrated on providing coherence for shared data. In this article, we examine how granularity-page-level versus cache-line level- and adaptivity-going from shared to private-affect the outcome of classification and its final impact on coherence. We create a classification technique, called Generational Classification, and a coherence protocol called Generational Coherence, which treats data as private or shared based on cache-line generations. We compare two coherence protocols based on self-invalidation/self-downgrade with respect to data classification. Our findings are enlightening: (i) Some programs benefit from finer granularity, some benefit further from adaptivity, but some do not benefit from either. (ii) Reducing the amount of shared data has no perceptible impact on coherence misses caused by self-invalidation of shared data, hence no impact on performance. (iii) In contrast, classifying more data as private has implications for protocols that employ write-through as a means of self-downgrade, resulting in network traffic reduction-up to 30%-by reducing write-through traffic.

    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-265580 (URN)10.1145/2790301 (DOI)000363004100001 ()
    Available from: 2015-10-06 Created: 2015-11-02 Last updated: 2017-12-01Bibliographically approved
    3. An efficient, self-contained, on-chip directory: DIR1-SISD
    Open this publication in new window or tab >>An efficient, self-contained, on-chip directory: DIR1-SISD
    2015 (English)In: Proc. 24th International Conference on Parallel Architectures and Compilation Techniques, IEEE Computer Society, 2015, p. 317-330Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    IEEE Computer Society, 2015
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-265611 (URN)10.1109/PACT.2015.23 (DOI)000378942700027 ()978-1-4673-9524-3 (ISBN)
    Conference
    PACT 2015, October 18–21, San Francisco, CA
    Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-04-22Bibliographically approved
    4. Scope-Aware Classification: Taking the hierarchical private/shared data classification to the next level
    Open this publication in new window or tab >>Scope-Aware Classification: Taking the hierarchical private/shared data classification to the next level
    2017 (English)Report (Other academic)
    Series
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2017-008
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-320324 (URN)
    Available from: 2017-04-27 Created: 2017-04-19 Last updated: 2017-07-03Bibliographically approved
    5. The best of both works: A hybrid data-race-free cache coherence scheme
    Open this publication in new window or tab >>The best of both works: A hybrid data-race-free cache coherence scheme
    2017 (English)Report (Other academic)
    National Category
    Computer Systems
    Identifiers
    urn:nbn:se:uu:diva-320320 (URN)
    Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-11-15
  • 75.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Scope-Aware Classification: Taking the hierarchical private/shared data classification to the next level2017Report (Other academic)
  • 76.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    The best of both works: A hybrid data-race-free cache coherence scheme2017Report (Other academic)
  • 77.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Ros, Alberto
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    An efficient, self-contained, on-chip directory: DIR1-SISD2015In: Proc. 24th International Conference on Parallel Architectures and Compilation Techniques, IEEE Computer Society, 2015, p. 317-330Conference paper (Refereed)
  • 78.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Ros, Alberto
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Effects of Granularity/Adaptivity on Private/Shared Classification for Coherence2015Conference paper (Other academic)
  • 79.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ros, Alberto
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    The Effects of Granularity and Adaptivity on Private/Shared Classification for Coherence2014Conference paper (Refereed)
  • 80.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Ros, Alberto
    Hagersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    The effects of granularity and adaptivity on private/shared classification for coherence2015In: ACM Transactions on Architecture and Code Optimization (TACO), ISSN 1544-3566, E-ISSN 1544-3973, Vol. 12, no 3, article id 26Article in journal (Refereed)
    Abstract [en]

    Classification of data into private and shared has proven to be a catalyst for techniques to reduce coherence cost, since private data can be taken out of coherence and resources can be concentrated on providing coherence for shared data. In this article, we examine how granularity-page-level versus cache-line level- and adaptivity-going from shared to private-affect the outcome of classification and its final impact on coherence. We create a classification technique, called Generational Classification, and a coherence protocol called Generational Coherence, which treats data as private or shared based on cache-line generations. We compare two coherence protocols based on self-invalidation/self-downgrade with respect to data classification. Our findings are enlightening: (i) Some programs benefit from finer granularity, some benefit further from adaptivity, but some do not benefit from either. (ii) Reducing the amount of shared data has no perceptible impact on coherence misses caused by self-invalidation of shared data, hence no impact on performance. (iii) In contrast, classifying more data as private has implications for protocols that employ write-through as a means of self-downgrade, resulting in network traffic reduction-up to 30%-by reducing write-through traffic.

  • 81.
    Davari, Mahdad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Ros, Alberto
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Kaxiras, Stefanos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    System and method for data classification and efficient virtual cache coherence without reverse translation2013Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    An on-chip memory hierarchy organization for a multicore processing system is disclosed. The hierarchy supports virtual- addressed private caches and a physical-addressed shared cache. The hierarchy classifies cache line data as private or shared to support a one-directional request response protocol. The classification can be determined from the generational behavior of a cache line in the private caches. Cache lines having a single generation in a private cache are Private, and cache lines having overlapping generations in two or more private caches are Shared. The Private or Shared classification is performed dynamically at run-time in hardware using a single translation lookaside buffer at the interface between the private and shared caches. The coherence protocol uses the data classification in a dynamic write policy for both shared data race free data and private data, differentiating in when data is put back to the shared cache based on the classification.

  • 82. Davis, Brandon
    et al.
    Baird, Ryan
    Gavin, Peter
    Själander, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Finlayson, Ian
    Rasapour, Farhad
    Cook, Gregory
    Uh, Gang-Ryung
    Whalley, David
    Tyson, Gary
    Scheduling instruction effects for a statically pipelined processor2015In: Proc. International Conference on Compilers, Architectures, and Synthesis for Embedded Systems: CASES 2015, Piscataway, NJ: IEEE Press, 2015, p. 167-176Conference paper (Refereed)
    Abstract [en]

    Statically pipelined processors have a fully exposed datapath where all portions of the pipeline are directly controlled by effects within an instruction, which simplifies hardware and enables a new level of compiler optimizations. This paper describes an effect scheduling strategy to aggressively compact instructions, which has a critical impact on code size and performance. Unique scheduling challenges include more frequent name dependences and fewer renaming opportunities due to static pipeline (SP) registers being dedicated for specific operations. We also realized the SP in a hardware implementation language (VHDL) to evaluate the real energy bene fits. Despite the compiler challenges, we achieve performance, code size, and energy improvements compared to a conventional MIPS processor.

  • 83.
    De Guglielmo, Domenico
    et al.
    Univ. of Pisa.
    Al Nahas, Beshr
    SICS.
    Duquennoy, Simon
    SICS.
    Voigt, Thiemo
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication. SICS, S-16429 Kista, Sweden.
    Anastasi, Giuseppe
    University of Pisa.
    Analysis and experimental evaluation of IEEE 802.15.4e TSCH CSMA-CA Algorithm2017In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 66, no 2, p. 1573-1588Article in journal (Refereed)
    Abstract [en]

    Time-slotted channel hopping (TSCH) is one of the medium access control (MAC) behavior modes defined in the IEEE 802.15.4e standard. It combines time-slotted access and channel hopping, thus providing predictable latency, energy efficiency, communication reliability, and high network capacity. TSCH provides both dedicated and shared links. The latter is special slots assigned to more than one transmitter, whose concurrent access is regulated by a carrier-sense multiple access with collision avoidance (CSMA-CA) algorithm. In this paper, we develop an analytical model of the TSCH CSMA-CA algorithm to predict the performance experienced by nodes when using shared links. The model allows for deriving a number of metrics, such as delivery probability, packet latency, and energy consumption of nodes. Moreover, it considers the capture effect (CE) that typically occurs in real wireless networks. We validate the model through simulation experiments and measurements in a real testbed. Our results show that the model is very accurate. Furthermore, we found that the CE plays a fundamental role as it can significantly improve the performance experienced by nodes.

  • 84.
    Duranton, Marc
    et al.
    CEA.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Yehia, Sami
    Thales.
    de Bosschere, Koen
    Ghent University.
    Computing Systems: Research Challenges Ahead: The HiPEAC Vision 2011/20122011Report (Other academic)
    Abstract [en]

    Computing Systems have a tremendous impact on everyday life in all domains, from the Internet to consumer electronics, transportation to manufacturing, medicine, energy, and scientific computing. In the future, computing systems will continue to be one of our most powerful tools for taking on the societal challenges shaping Europe, its values, and its global competitiveness.

    The FP7 HiPEAC network of excellence is Europe’s premier organization for coordinating research, improving mobility, and enhancing visibility in the computing system field. HiPEAC covers all computing

    market segments: embedded systems, general purpose computing systems, data centers and high performance computing. Created in 2004, HiPEAC today gathers over 250 leading European academic and industrial computing system research- ers from about 100 universities and 50 companies in one virtual centre of excellence. To encourage computing systems innovation in Europe, HiPEAC provides collaboration grants, internships, sabbaticals, and improves networking through the yearly HiPEAC conference, ACACES summer school, and the semiannual computing systems week.

    In this roadmap document, HiPEAC leverages the broad expertise of its members to identify and analyze the key challenges for computing systems in Europe over the next decade. While advances in computing systems have been consistent and dra- matic over the past fifty years, its future today is not as certain. To continue to be a tool for providing new and innovative solu- tions, the computing systems community must face serious challenges in efficiency, complexity, and dependability.

  • 85. Eigenmann, Rudolf
    Efficient thread/page/parallelism autotuning for NUMA systems2019Conference proceedings (editor) (Refereed)
  • 86.
    Eklöv, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    A Profiling Method for Analyzing Scalability Bottlenecks on Multicores2012Report (Other academic)
  • 87.
    Eklöv, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Nikoleris, Nikos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Black-Schaffer, David
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Hägersten, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Quantitative Characterization of Memory Contention2012Report (Other academic)
    Abstract [en]

    On multicore processors, co-executing applications compete for shared resources, such as cache capacity and memory bandwidth. This leads to suboptimal resource allocation and can cause substantial performance loss, which makes it important to effectively manage these shared resources. This, however, requires insights into how the applications are impacted by such resource sharing.

    While there are several methods to analyze the performance impact of cache contention, less attention has been paid to general, quantitative methods for analyzing the impact of contention for memory bandwidth. To this end we introduce the Bandwidth Bandit, a general, quantitative, profiling method for analyzing the performance impact of contention for memory bandwidth on multicore machines.

    The profiling data captured by the Bandwidth Bandit is presented in a it bandwidth graph. This graph accurately captures the measured application's performance as a function of its available memory bandwidth, and enables us to determine how much the application suffers when its available bandwidth is reduced. To demonstrate the value of this data, we present a case study in which we use the bandwidth graph to analyze the performance impact of memory contention when co-running multiple instances of single threaded application.

  • 88.
    Eladhari, Mirjam Palosaari
    Gotland University, School of Game Design, Technology and Learning Processes.
    Characterising action potential in virtual game worlds applied with the mind module2011Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term semiautonomy is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of 'mood'. The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships. There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can 'feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the 'mental physics' of the MM may open up new possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood PCs are in they can cast different 'spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which 'affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities.Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term \textit{semiautonomy} is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of 'mood'. The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships. There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can 'feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the 'mental physics' of the MM may open up new possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood PCs are in they can cast different 'spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which 'affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities. 

  • 89. Enemark, Hans-Jacob
    et al.
    Zhang, Yue
    Dragoni, Nicola
    Orfanidis, Charalampos
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Architecture and Computer Communication.
    Energy-efficient fault-tolerant dynamic event region detection in wireless sensor networks2015In: Proc. 81st IEEE Vehicular Technology Conference, IEEE conference proceedings, 2015Conference paper (Refereed)
    Abstract [en]

    Fault-tolerant event detection is fundamental to wireless sensor network applications. Existing approaches usually adopt neighborhood collaboration for better detection accuracy,while need more energy consumption due to communication.Focusing on energy efficiency, this paper makes an improvement to a hybrid algorithm for dynamic event region detection, such asreal-time tracking of chemical leakage regions. Considering the characteristics of the moving away dynamic events, we propose areturn back condition for the hybrid algorithm from distributed neighborhood collaboration, in which a node makes its detection decision based on decisions received from its spatial and temporal neighbors, to local non-communicative decision making. The simulation results demonstrate that the improved algorithm doesnot degrade the detection accuracy of the original algorithm,while it has better energy efficiency with the number of messages exchanged in the network decreased.

  • 90.
    Eriksson, Jenny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Dahlqvist, Matilda
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Svensson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Measurement system with image analysis: Detecting signal disturbances in the Head-up display of the JAS 39 Gripen2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A measurement system has been developed to detect errors in the head-up display ofJAS 39 Gripen. Errors have been identified by continuously capturing images of thedisplay and comparing it to a reference image. Signal acquisition has been madeconcurrently with a Data Acquisition device and the data has been processed andanalyzed in LabVIEW, a visual programming tool.The resulting measurement system functioned as intended. There was an uncertaintyin the time stamp of the logged error, with a standard deviation of 15.1 ms.

  • 91. Faili, Heshaam
    et al.
    Basirat, Ali
    An Unsupervised Approach for Linking Automatically Extracted and Manually Crafted LTAGs2011In: Computational Linguistics and Intelligent Text Processing: 12th International Conference, CICLing 2011, Tokyo, Japan, February 20-26, 2011. Proceedings, Part I / [ed] Gelbukh, Alexander F., Springer Berlin/Heidelberg, 2011, p. 68-81Chapter in book (Refereed)
    Abstract [en]

    Though the lack of semantic representation of automatically extracted LTAGs is an obstacle in using these formalism, due to the advent of some powerful statistical parsers that were trained on them, these grammars have been taken into consideration more than before. Against of this grammatical class, there are some widely usage manually crafted LTAGs that are enriched with semantic representation but suffer from the lack of efficient parsers. The available representation of latter grammars beside the statistical capabilities of former encouraged us in constructing a link between them.

    Here, by focusing on the automatically extracted LTAG used by MICA [4] and the manually crafted English LTAG namely XTAG grammar [32], a statistical approach based on HMM is proposed that maps each sequence of former elementary trees onto a sequence of later elementary trees. To avoid of converging the HMM training algorithm in a local optimum state, an EM-based learning process for initializing the HMM parameters were proposed too. Experimental results show that the mapping method can provide a satisfactory way to cover the deficiencies arises in one grammar by the available capabilities of the other.

  • 92.
    Farisco, Michele
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics. Science and Society Unit, Biogem Genetic Research Centre, Ariano Irpino (AV), Italy.
    Hellgren Kotaleski, Jeanette
    Science for Life Laboratory, School of Computer Science and Communication, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Neuroscience, Karolinska Institute, Solna, Sweden.
    Evers, Kathinka
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Large-scale brain simulation and disorders of consciousness: Mapping technical and conceptual issues2018In: Frontiers in Psychology, ISSN 1664-1078, E-ISSN 1664-1078, Vol. 9, article id 585Article in journal (Refereed)
    Abstract [en]

    Modelling and simulations have gained a leading position in contemporary attempts to describe, explain, and quantitatively predict the human brain's operations. Computer models are highly sophisticated tools developed to achieve an integrated knowledge of the brain with the aim of overcoming the actual fragmentation resulting from different neuroscientific approaches. In this paper we investigate plausibility of simulation technologies for emulation of consciousness and the potential clinical impact of large-scale brain simulation on the assessment and care of disorders of consciousness (DOCs), e.g. Coma, Vegetative State/Unresponsive Wakefulness Syndrome, Minimally Conscious State.Notwithstanding their technical limitations, we suggest that simulation technologies may offer new solutions to old practical problems, particularly in clinical contexts. We take DOCs as an illustrative case, arguing that the simulation of neural correlates of consciousness is potentially useful for improving treatments of patients with DOCs.

  • 93.
    Feeney, Laura Marie
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems.
    Self-organizing TDMA for multihop networks2011Other (Refereed)
  • 94.
    Fernandez-Reyes, Kiko
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Clarke, Dave
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Castegren, Elias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Vo, Huu-Phuc
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Forward to a Promising Future2018In: Conference proceedings COORDINATION 2018, 2018Conference paper (Refereed)
    Abstract [en]

    In many actor-based programming models, asynchronous method calls communicate their results using futures, where the fulfilment occurs under-the-hood. Promises play a similar role to futures, except that they must be explicitly created and explicitly fulfilled; this makes promises more flexible than futures, though promises lack fulfilment guarantees: they can be fulfilled once, multiple times or not at all. Unfortunately, futures are too rigid to exploit many available concurrent and parallel patterns. For instance, many computations block on a future to get its result only to return that result immediately (to fulfil their own future). To make futures more flexible, we explore a construct, forward, that delegates the responsibility for fulfilling the current implicit future to another computation. Forward reduces synchronisation and gives futures promise-like capabilities. This paper presents a formalisation of the forward construct, defined in a high-level source language, and a compilation strategy from the high-level language to a low-level, promised-based target language. The translation is shown to preserve semantics. Based on this foundation, we describe the implementation of forward in the parallel, actor-based language Encore, which compiles to C.

  • 95.
    Fernandez-Reyes, Kiko
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Clarke, Dave
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Hornbach, Janina
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Business Studies.
    The impact of opt-in gamification on students' grades in a software design course2018In: Proceedings of the 21st ACM/IEEE International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings, New York, NY, USA: ACM Publications, 2018, p. -97Conference paper (Refereed)
    Abstract [en]

    An achievement-driven methodology strives to give students more control of their learning with enough flexibility to engage them in deeper learning.

    We observed in the course Advanced Software Design, which uses the achievement-driven methodology, that students fail to get high grades, which may hamper deeper learning. To motivate students to pursue and get higher grades we added gamification elements to the course.

    To measure the success of our gamification implementation, students filled out a questionaire rating the enjoyment and motivation produced by the game. We built a statistical regression model where enjoyment and motivation explain 55% of the variation in grades. However, only the relationship between motivation and grade is significant, which implies that notivation drives the overall effect of the model. The results suggest that the more the students were motivated by the game, the higher their grades on the course (and vice versa). This implies that if gamification indeed motivates students, then it makes them go beyond what is expected.

  • 96.
    Fernandez-Reyes, Kiko
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Clarke, Dave
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    McCain, Daniel S.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    ParT: An asynchronous parallel abstraction for speculative pipeline computations2016In: Coordination Models and Languages / [ed] Lafuente, AL; Proenca, J, Springer, 2016, p. 101-120Conference paper (Refereed)
    Abstract [en]

    The ubiquity of multicore computers has forced programming language designers to rethink how languages express parallelism and concurrency. This has resulted in new language constructs and new combinations or revisions of existing constructs. In this line, we extended the programming languages Encore (actor-based), and Clojure (functional) with an asynchronous parallel abstraction called ParT, a data structure that can dually be seen as a collection of asynchronous values (integrating with futures) or a handle to a parallel computation, plus a collection of combinators for manipulating the data structure. The combinators can express parallel pipelines and speculative parallelism. This paper presents a typed calculus capturing the essence of ParT, abstracting away from details of the Encore and Clojure programming languages. The calculus includes tasks, futures, and combinators similar to those of Orc but implemented in a non-blocking fashion. Furthermore, the calculus strongly mimics how ParT is implemented, and it can serve as the basis for adaptation of ParT into different languages and for further extensions.

  • 97. Franco, Juliana
    et al.
    Clebsch, Sylvan
    Drossopoulou, Sophia
    Vitek, Jan
    Wrigstad, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Correctness of a concurrent object collector for actor languages2018In: Programming Languages and Systems, Springer, 2018, p. 885-911Conference paper (Refereed)
  • 98. Franco, Juliana
    et al.
    Hagelin, Martin
    Wrigstad, Tobias
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Drossopoulou, Sophia
    Eisenbach, Susan
    You can have it all: abstraction and good cache performance2017Conference paper (Refereed)
  • 99.
    Fridenfalk, Mikael
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Game Design.
    A Generic Method for Distribution of Examination Problems in e-Learning2018In: 2018 IEEE 7ih Global Conference on Consumer Electronics (GCCE 2018), IEEE, 2018, p. 645-646Conference paper (Refereed)
    Abstract [en]

    A method is proposed for the distribution of examination problems over multiple course events, to maximize variation and minimize predictability, primarily targeting mathematics education, but generically applicable to all types of examination papers where problems can be quantified along at least two independent dimensions. The suggested method is based on experience gained from the development and implementation of an automatic system for the generation of examination papers in a discrete mathematics course at Uppsala University in Sweden.

  • 100.
    Fridenfalk, Mikael
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Game Design.
    A Simplified Representation of Finite State Machines by Generic States2014In: Nicograph International 2014, 2014, p. 163-164Conference paper (Refereed)
    Abstract [en]

    Wildcards are of significant value for the simplification of state diagrams and truth tables for the representation of finite state machines. In this paper a new type of wildcard is introduced, called a generic state, which without any loss of information may further simplify such representations.

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