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  • 72651.
    Ålund, Murielle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Whittington, Emma
    Center for Reproductive Evolution, 248 Life Sciences Complex, Syracuse, NY 13244, USA.
    Backström, Niclas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Borziak, Kirill
    Center for Reproductive Evolution, 248 Life Sciences Complex, Syracuse, NY 13244, USA.
    Jones, Williams
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    McFarlane, S. Eryn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Mugal, Carina F.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Wang, Mi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Wheatcroft, David
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Xu, Luohao
    University of Vienna, Austria.
    Ellegren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Immler, Simone
    School of Biological Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK.
    Dorus, Steve
    Center for Reproductive Evolution, 248 Life Sciences Complex, Syracuse, NY 13244, USA.
    Qvarnström, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Reproductive -omics of a wild avian speciation model unveils candidate genes for gamete interactionManuscript (preprint) (Other academic)
    Abstract [en]

    The complex nature of interspecific interactions contributing to reproductive isolation means that we still know little about their molecular basis. Male reproductive traits are notorious for their fast evolution at the phenotypic and genotypic level, and divergence in components of the ejaculate can lead to incompatibilities between closely related species. Making use of recent advances of molecular tools and the extensive knowledge on the biology and ecology of young sister species, here the pied (Ficedula hypoleuca) and collared flycatcher (F. albicollis), allows the identification of candidate phenotypes and the underlying genotypes maintaining species boundaries. Pied flycatcher females can avoid costly production of sterile hybrids when mated to collared flycatchers by cryptically favouring conspecific sperm. Here, we describe the testes transcriptome and sperm proteome of both species, confirm the complexity of avian sperm development and functions and identify several candidate genes for interactions between sperm and the female reproductive tract, using multiple independent measures of divergence between the species. We show that divergence at the transcriptional and translational levels can potentially lead to the evolution of reproductive incompatibilities despite low levels of sequence divergence, and suggest that integrating several -omics techniques with knowledge of the biology of naturally hybridizing species will greatly improve our understanding of the molecular basis of speciation in the near future. 

  • 72652.
    Ålund née Podevin, Murielle
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sex, Sperm and Speciation: On sexual selection and fertility in hybridizing flycatchers2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Sexual reproduction entails complex co-evolution between the sexes, necessary for successful fertilization, ensuring individual and population-level fitness. Interfertility is the main criterion for species definition and understanding speciation requires detailed studies of reproductive barriers. However, many studies on reproductive barriers are constrained to infer evolutionary processes from patterns. In this thesis, I focus on a hybrid zone between collared and pied flycatchers (Ficedula albicollis and hypoleuca) on the island of Öland, and a trait that is essential for fertilization: sperm. Long-term monitoring of these species, combined with recent advances in molecular tools, allow me to study how complex on-going intersexual and interspecific interactions influence reproductive isolation in this young hybrid zone. I start by exploring the links between pre- and postmating sexual selection within collared flycatchers (paper I and II). I show that secondary sexual characters and indirect mate-choice benefits are tightly linked to physiology (paper I), and that a male’s attractiveness and dominance status dictate which sperm traits are optimal, as a male’s fertilization success depends on an interaction between sperm and display traits (paper II). I then report a source of strong postzygotic isolation between recently diverged collared and pied flycatchers: impaired spermatogenesis resulting in absence of mature sperm cells in hybrid males (paper III). I show however that pied flycatcher females, who are most exposed to hybridization, can mitigate these costs through mechanisms of cryptic female choice impairing heterospecific sperm performance, allowing them to bias paternity towards pure-species offspring (paper IV). Finally, by exploring the testes transcriptomes and sperm proteomes of both species, I highlight the importance of gene and protein regulation mechanisms in facilitating phenotypic divergence between these species (paper V). Thus, my thesis reveals complex interactions between primary and secondary sexual characters in a wild bird and suggests that mechanisms of sexual selection are tightly linked to essential physiological functions. I also show that genetic incompatibilities can evolve rapidly despite low genome-wide levels of divergence but that divergence in regulatory regions and proteins potentially allows fast evolution of molecular mechanisms impairing or preventing costly heterospecific fertilization. 

    List of papers
    1. Sexual selection affects climate adaptation in collared flycatchers
    Open this publication in new window or tab >>Sexual selection affects climate adaptation in collared flycatchers
    2017 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The role of sexual selection in climate adaptation is debated. We tested whether sexual selection has the potential to speed up adaptation to thermal conditions in a natural population of collared flycatchers. Based on a three-year cross-fostering experiment, we found that the size of a sexually selected trait predicted offspring metabolic rate: male collared flycatchers with large forehead patches sired offspring with low metabolic rate regardless of the ambient temperature. Thus, there was a stable significant relationship between forehead patch size of genetic fathers and offspring metabolic rate. Nestlings with high metabolic rate experienced a survival advantage when growing under warm temperatures, while the opposite was true in cold environments. Our study shows that females can modulate their offspring’s physiology through mate choice, and that sexual selection can thus affect climate adaptation.

    Keywords
    sexual selection, climate adaptation, resting metabolic rate, Ficedula flycatcher, secondary sexual character, physiology
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-322788 (URN)
    Available from: 2017-07-30 Created: 2017-07-30 Last updated: 2017-07-30
    2. Revisiting the definition of “sperm quality”: selection on sperm length depends on a male’s attractiveness and dominance in wild collared flycatchers
    Open this publication in new window or tab >>Revisiting the definition of “sperm quality”: selection on sperm length depends on a male’s attractiveness and dominance in wild collared flycatchers
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Dominance over rivals, sexual attractiveness and highly efficient ejaculates are all known to be essential for male fertilization success but the theories of how primary and secondary sexual characters may co-evolve largely remain to be tested. Here, we measure sperm morphology in 131 wild-caught collared flycatchers over a four-year period and investigate the links between male display traits, sperm characteristics and siring success among 425 offspring sired by 71 of these males. We show that the optimal sperm length to attain high relative fertilization success depends on the size of a male’s secondary sexual character. Males with small ornaments sire more offspring in their own nest when they produce long sperm and vice-versa. These results are not compatible with theories based on simple relationships between secondary sexual traits and sperm “quality” but imply that the optimal fertilization strategy (and hence optimal sperm traits) differ between males even in a predominantly socially monogamous population with moderate extra-pair copulation rates. Thus, a better knowledge of the complex chain of behavioural interactions between the sexes and their gametes is needed for a complete understanding of how sexual selection operates in nature.

    Keywords
    sperm morphology, secondary sexual character, mating strategy, fertilization success, Ficedula flycatcher, extra-pair copulation
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-326808 (URN)
    Available from: 2017-07-30 Created: 2017-07-30 Last updated: 2017-07-30
    3. Low fertility of wild hybrid male flycatchers despite recent divergence
    Open this publication in new window or tab >>Low fertility of wild hybrid male flycatchers despite recent divergence
    2013 (English)In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 9, no 3, article id 20130169Article in journal (Refereed) Published
    Abstract [en]

    Postzygotic isolation may be important for maintaining species boundaries, particularly when premating barriers are incomplete. Little is known about the course of events leading from minor environmental mismatches affecting hybrid fitness to severe genetic incompatibilities causing sterility or inviability. We investigated whether reduced reproductive success of hybrid males was caused by suboptimal sperm traits or by more severe genetic incompatibilities in a hybrid zone of pied (Ficedula hypoleuca) and collared flycatchers (F. albicollis) on the island of Oland, Sweden. About 4 per cent hybridization is observed in this population and all female hybrids are sterile. We found no sperm in the ejaculates of most sampled hybrid males, and sperm with abnormal morphology in two hybrids. Furthermore, none of the hybrids sired any offspring because of high levels of hatching failure and extra-pair paternity in their nests. These results from a natural hybrid zone suggest that the spermatogenesis of hybrid males may become disrupted despite little genetic divergence between the parental species.

    Keywords
    hybrid, sterility-infertility, flycatcher, sperm, postzygotic incompatibility
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-202341 (URN)10.1098/rsbl.2013.0169 (DOI)000318762300035 ()
    Available from: 2013-06-24 Created: 2013-06-24 Last updated: 2017-12-06Bibliographically approved
    4. Females discriminate against heterospecific sperm in a natural hybrid zone
    Open this publication in new window or tab >>Females discriminate against heterospecific sperm in a natural hybrid zone
    Show others...
    2016 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 70, no 8, p. 1844-1855Article in journal (Refereed) Published
    Abstract [en]

    When hybridization is maladaptive, species-specific mate preferences are selectively favored, but low mate availability may constrain species-assortative pairing. Females paired to heterospecifics may then benefit by copulating with multiple males and subsequently favoring sperm of conspecifics. Whether such mechanisms for biasing paternity toward conspecifics act as important reproductive barriers in socially monogamous vertebrate species remains to be determined. We use a combination of long-term breeding records from a natural hybrid zone between collared and pied flycatchers (Ficedula albicollis and F. hypoleuca), and an in vitro experiment comparing conspecific and heterospecific sperm performance in female reproductive tract fluid, to evaluate the potential significance of female cryptic choice. We show that the females most at risk of hybridizing (pied flycatchers) frequently copulate with multiple males and are able to inhibit heterospecific sperm performance. The negative effect on heterospecific sperm performance was strongest in pied flycatcher females that were most likely to have been previously exposed to collared flycatcher sperm. We thus demonstrate that a reproductive barrier acts after copulation but before fertilization in a socially monogamous vertebrate. While the evolutionary history of this barrier is unknown, our results imply that there is opportunity for it to be accentuated via a reinforcement-like process.

    Keywords
    Cryptic female choice, hybrid zones, postcopulatory prezygotic barriers, reinforcement, speciation, sexual selection
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-303102 (URN)10.1111/evo.12986 (DOI)000381205700013 ()
    Funder
    Swedish Research Council, 621-2012-3722The Royal Swedish Academy of Sciences
    Available from: 2016-10-05 Created: 2016-09-15 Last updated: 2018-08-10Bibliographically approved
    5. Reproductive -omics of a wild avian speciation model unveils candidate genes for gamete interaction
    Open this publication in new window or tab >>Reproductive -omics of a wild avian speciation model unveils candidate genes for gamete interaction
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The complex nature of interspecific interactions contributing to reproductive isolation means that we still know little about their molecular basis. Male reproductive traits are notorious for their fast evolution at the phenotypic and genotypic level, and divergence in components of the ejaculate can lead to incompatibilities between closely related species. Making use of recent advances of molecular tools and the extensive knowledge on the biology and ecology of young sister species, here the pied (Ficedula hypoleuca) and collared flycatcher (F. albicollis), allows the identification of candidate phenotypes and the underlying genotypes maintaining species boundaries. Pied flycatcher females can avoid costly production of sterile hybrids when mated to collared flycatchers by cryptically favouring conspecific sperm. Here, we describe the testes transcriptome and sperm proteome of both species, confirm the complexity of avian sperm development and functions and identify several candidate genes for interactions between sperm and the female reproductive tract, using multiple independent measures of divergence between the species. We show that divergence at the transcriptional and translational levels can potentially lead to the evolution of reproductive incompatibilities despite low levels of sequence divergence, and suggest that integrating several -omics techniques with knowledge of the biology of naturally hybridizing species will greatly improve our understanding of the molecular basis of speciation in the near future. 

    Keywords
    Reproductive isolation, cryptic female choice, sperm, proteomics, transcriptomics, Ficedula flycatchers
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-326809 (URN)
    Available from: 2017-07-30 Created: 2017-07-30 Last updated: 2017-07-30
  • 72653.
    Åman Pohjola, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Bells and Whistles: Advanced language features in psi-calculi2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Psi-calculi is a parametric framework for process calculi similar to popular pi-calculus extensions such as the explicit fusion calculus, the applied pi-calculus and the spi calculus. Remarkably, machine-checked proofs of standard algebraic and congruence properties of bisimilarity apply to every instance of the framework.

    The contribution of this licentiate thesis is to significantly extend the applicability and expressiveness of psi-calculi by incorporating several advanced language features into the framework: broadcasts, higher-order communication, generalised pattern matching, sorts and priorities. The extensions present several interesting technical challenges, such as negative premises. The machine-checked proofs for standard results about bisimilarity are generalised to each of these new settings, and the proof scripts are freely available online.

    List of papers
    1. Broadcast psi-calculi with an application to wireless protocols
    Open this publication in new window or tab >>Broadcast psi-calculi with an application to wireless protocols
    Show others...
    2015 (English)In: Software and Systems Modeling, ISSN 1619-1366, E-ISSN 1619-1374, Vol. 14, no 1, p. 201-216Article in journal (Refereed) Published
    Abstract [en]

    Psi-calculi is a parametric framework for extensions of the pi-calculus, with arbitrary data structures and logical assertions for facts about data. In this paper we add primitives for broadcast communication in order to model wireless protocols. The additions preserve the purity of the psi-calculi semantics, and we formally prove the standard congruence and structural properties of bisimilarity. We demonstrate the expressive power of broadcast psi-calculi by modelling the wireless ad-hoc routing protocol LUNAR and verifying a basic reachability property.

    Place, publisher, year, edition, pages
    Springer, 2015
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-205258 (URN)10.1007/s10270-013-0375-z (DOI)000349026100012 ()
    Projects
    UPMARCProFuN
    Funder
    Swedish Research Council, 2013-4853
    Available from: 2013-11-08 Created: 2013-08-15 Last updated: 2018-01-11Bibliographically approved
    2. Higher-order psi-calculi
    Open this publication in new window or tab >>Higher-order psi-calculi
    2014 (English)In: Mathematical Structures in Computer Science, ISSN 0960-1295, E-ISSN 1469-8072, Vol. 24, no 2, article id e240203Article in journal (Refereed) Published
    Abstract [en]

    Psi-calculi is a parametric framework for extensions of the pi-calculus; in earlier work we have explored their expressiveness and algebraic theory. In this paper we consider higher-order psi-calculi through a technically surprisingly simple extension of the framework, and show how an arbitrary psi-calculus can be lifted to its higher-order counterpart in a canonical way. We illustrate this with examples and establish an algebraic theory of higher-order psi-calculi. The formal results are obtained by extending our proof repositories in Isabelle/Nominal.

    Place, publisher, year, edition, pages
    Cambridge University Press, 2014
    Keywords
    process calculi, psi calculi, isabelle, theorem proving, nominal, higher-order
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-183610 (URN)10.1017/S0960129513000170 (DOI)000343643500003 ()
    Projects
    UPMARCProFuN
    Funder
    Swedish Foundation for Strategic Research
    Available from: 2013-06-24 Created: 2012-10-30 Last updated: 2018-01-12Bibliographically approved
    3. A Sorted Semantic Framework for Applied Process Calculi (extended abstract)
    Open this publication in new window or tab >>A Sorted Semantic Framework for Applied Process Calculi (extended abstract)
    Show others...
    2014 (English)In: Trustworthy Global Computing: TGC 2013, Springer Berlin/Heidelberg, 2014, p. 103-118Conference paper, Published paper (Refereed)
    Abstract [en]

    Applied process calculi include advanced programming constructs such as type systems, communication with pattern matching, encryption primitives, concurrent constraints, nondeterminism, process creation, and dynamic connection topologies. Several such formalisms, e.g. the applied pi calculus,  are extensions of the the pi-calculus; a growing number is geared towards particular applications or computational paradigms.

    Our goal is a unified framework to represent different process calculi and notions of computation. To this end, we extend our previous work on psi-calculi with novel abstract patterns and pattern matching, and add sorts to the data term language, giving sufficient criteria for subject reduction to hold. Our framework can accommodate several existing process calculi; the resulting transition systems are isomorphic to the originals up to strong bisimulation. We also demonstrate  different notions of computation on data terms, including cryptographic primitives and a lambda-calculus with erratic choice. Substantial parts of the meta-theory of sorted psi-calculi have been machine-checked using Nominal Isabelle.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2014
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 8358
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-203382 (URN)10.1007/978-3-319-05119-2_7 (DOI)978-3-319-05118-5 (ISBN)
    Conference
    8th International Symposium on Trustworthy Global Computing, August 30-31, 2013, Buenos Aires, Argentina
    Projects
    UPMARCProFuN
    Funder
    Swedish Foundation for Strategic Research , RIT08­0065
    Available from: 2014-03-08 Created: 2013-07-09 Last updated: 2018-01-11
    4. Negative premises in applied process calculi
    Open this publication in new window or tab >>Negative premises in applied process calculi
    Show others...
    2013 (English)Report (Other academic)
    Series
    Technical report / Department of Information Technology, Uppsala University, ISSN 1404-3203 ; 2013-014
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-229004 (URN)
    Available from: 2013-06-20 Created: 2014-07-25 Last updated: 2018-01-11Bibliographically approved
    5. Bisimulation up-to techniques for psi-calculi
    Open this publication in new window or tab >>Bisimulation up-to techniques for psi-calculi
    2016 (English)In: Proc. 5th ACM SIGPLAN Conference on Certified Programs and Proofs / [ed] Avigad, J; Chlipala, A, New York: ACM Press, 2016, p. 142-153Conference paper, Published paper (Refereed)
    Abstract [en]

    Psi-calculi is a parametric framework for process calculi similar to popular pi-calculus extensions such as the explicit fusion calculus, the applied pi-calculus and the spi calculus. Remarkably, machine-checked proofs of standard algebraic and congruence properties of bisimilarity apply to all calculi within the framework. Bisimulation up-to techniques are methods for reducing the size of relations needed in bisimulation proofs. In this paper, we show how these bisimulation proof methods can be adapted to psi-calculi. We formalise all our definitions and theorems in Nominal Isabelle, and show examples where the use of up to-techniques yields drastically simplified proofs of known results. We also prove new structural laws about the replication operator.

    Place, publisher, year, edition, pages
    New York: ACM Press, 2016
    Keywords
    Bisimulation up-to, process calculus, psi-calculi, Isabelle, Nominal Isabelle, nominal logic
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-229008 (URN)10.1145/2854065.2854080 (DOI)000389021600016 ()9781450341271 (ISBN)
    Conference
    CPP 2016, January 18–19, Saint Petersburg, FL
    Available from: 2016-01-18 Created: 2014-07-25 Last updated: 2018-01-11Bibliographically approved
  • 72654.
    Åman Pohjola, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computing Science.
    Culling Concurrency Theory: Reusable and trustworthy meta-theory, proof techniques and separation results2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    As concurrent systems become ever more complex and ever more ubiquitous, the need to understand and verify them grows ever larger. For this we need formal modelling languages that are well understood, with rigorously verified foundations and proof techniques, applicable to a wide variety of concurrent systems.

    Defining modelling languages is easy; there is a stupefying variety of them in the literature. Verifying their foundations and proof techniques, and developing an understanding of their interrelationship with other modelling languages, is difficult, tedious and error-prone. The contributions of this thesis support these tasks in reusable and trustworthy ways, by results that apply to a wide variety of modelling languages, verified to the highest standards of mathematical rigour in an interactive theorem prover.

    To this end, we extend psi-calculi - a family of process calculi with reusable foundations for formal verification - with several new language features. We prove that the bisimulation meta-theory of psi-calculi carries over to these extended settings. This widens the scope of psi-calculi to important application areas, such as cryptography and wireless communication. We develop bisimulation up-to techniques - powerful proof techniques for showing that two processes exhibit the same observable behaviour - that apply to all psi-calculi. By showing how psi-calculi can encode dynamic priorities under very strong quality criteria, we demonstrate that the expressive power is greater than previously thought. Finally, we develop a simple and widely applicable technique for showing that a process calculus adds expressiveness over another, based on little more than whether parallel components may act independently or not. Many separation results, both novel ones and strengthenings of known results from the literature, emerge as special cases of this technique.

    List of papers
    1. Broadcast psi-calculi with an application to wireless protocols
    Open this publication in new window or tab >>Broadcast psi-calculi with an application to wireless protocols
    Show others...
    2015 (English)In: Software and Systems Modeling, ISSN 1619-1366, E-ISSN 1619-1374, Vol. 14, no 1, p. 201-216Article in journal (Refereed) Published
    Abstract [en]

    Psi-calculi is a parametric framework for extensions of the pi-calculus, with arbitrary data structures and logical assertions for facts about data. In this paper we add primitives for broadcast communication in order to model wireless protocols. The additions preserve the purity of the psi-calculi semantics, and we formally prove the standard congruence and structural properties of bisimilarity. We demonstrate the expressive power of broadcast psi-calculi by modelling the wireless ad-hoc routing protocol LUNAR and verifying a basic reachability property.

    Place, publisher, year, edition, pages
    Springer, 2015
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-205258 (URN)10.1007/s10270-013-0375-z (DOI)000349026100012 ()
    Projects
    UPMARCProFuN
    Funder
    Swedish Research Council, 2013-4853
    Available from: 2013-11-08 Created: 2013-08-15 Last updated: 2018-01-11Bibliographically approved
    2. Higher-order psi-calculi
    Open this publication in new window or tab >>Higher-order psi-calculi
    2014 (English)In: Mathematical Structures in Computer Science, ISSN 0960-1295, E-ISSN 1469-8072, Vol. 24, no 2, article id e240203Article in journal (Refereed) Published
    Abstract [en]

    Psi-calculi is a parametric framework for extensions of the pi-calculus; in earlier work we have explored their expressiveness and algebraic theory. In this paper we consider higher-order psi-calculi through a technically surprisingly simple extension of the framework, and show how an arbitrary psi-calculus can be lifted to its higher-order counterpart in a canonical way. We illustrate this with examples and establish an algebraic theory of higher-order psi-calculi. The formal results are obtained by extending our proof repositories in Isabelle/Nominal.

    Place, publisher, year, edition, pages
    Cambridge University Press, 2014
    Keywords
    process calculi, psi calculi, isabelle, theorem proving, nominal, higher-order
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-183610 (URN)10.1017/S0960129513000170 (DOI)000343643500003 ()
    Projects
    UPMARCProFuN
    Funder
    Swedish Foundation for Strategic Research
    Available from: 2013-06-24 Created: 2012-10-30 Last updated: 2018-01-12Bibliographically approved
    3. A Sorted Semantic Framework for Applied Process Calculi
    Open this publication in new window or tab >>A Sorted Semantic Framework for Applied Process Calculi
    Show others...
    2016 (English)In: Logical Methods in Computer Science, ISSN 1860-5974, E-ISSN 1860-5974, Vol. 12, no 1, p. 1-49, article id 8Article in journal (Refereed) Published
    Abstract [en]

    Applied process calculi include advanced programming constructs such as type systems, communication with pattern matching, encryption primitives, concurrent constraints, nondeterminism, process creation, and dynamic connection topologies. Several such formalisms, e.g. the applied pi calculus, are extensions of the the pi-calculus; a growing number is geared towards particular applications or computational paradigms.

    Our goal is a unified framework to represent different process calculi and notions of computation. To this end, we extend our previous work on psi-calculi with novel abstract patterns and pattern matching, and add sorts to the data term language, giving sufficient criteria for subject reduction to hold. Our framework can directly represent several existing process calculi; the resulting transition systems are isomorphic to the originals up to strong bisimulation. We also demonstrate different notions of computation on data terms, including cryptographic primitives and a lambda-calculus with erratic choice. Finally, we prove standard congruence and structural properties of bisimulation; the proof has been machine-checked using Nominal Isabelle in the case of a single name sort.

    Keywords
    Expressiveness, Pattern matching, Type systems, Theorem proving, pi-calculus, Nominal sets
    National Category
    Computer Sciences
    Research subject
    Computer Science
    Identifiers
    urn:nbn:se:uu:diva-262199 (URN)10.2168/LMCS-12(1:8)2016 (DOI)000374769600004 ()
    Projects
    UPMARC
    Funder
    Swedish Research Council, 2013-4853
    Available from: 2016-03-31 Created: 2015-09-09 Last updated: 2019-02-25Bibliographically approved
    4. Priorities Without Priorities: Representing Preemption in Psi-Calculi
    Open this publication in new window or tab >>Priorities Without Priorities: Representing Preemption in Psi-Calculi
    2014 (English)In: Proc. 21st International Workshop on Expressiveness in Concurrency, and 11th Workshop on Structural Operational Semantics, 2014, p. 2-15Conference paper, Published paper (Refereed)
    Series
    Electronic Proceedings in Theoretical Computer Science, ISSN 2075-2180 ; 160
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-297468 (URN)10.4204/EPTCS.160.2 (DOI)
    Conference
    EXPRESS/SOS 2014, September 1st, Rome, Italy
    Available from: 2014-08-07 Created: 2016-06-23 Last updated: 2018-01-10Bibliographically approved
    5. Bisimulation up-to techniques for psi-calculi
    Open this publication in new window or tab >>Bisimulation up-to techniques for psi-calculi
    2016 (English)In: Proc. 5th ACM SIGPLAN Conference on Certified Programs and Proofs / [ed] Avigad, J; Chlipala, A, New York: ACM Press, 2016, p. 142-153Conference paper, Published paper (Refereed)
    Abstract [en]

    Psi-calculi is a parametric framework for process calculi similar to popular pi-calculus extensions such as the explicit fusion calculus, the applied pi-calculus and the spi calculus. Remarkably, machine-checked proofs of standard algebraic and congruence properties of bisimilarity apply to all calculi within the framework. Bisimulation up-to techniques are methods for reducing the size of relations needed in bisimulation proofs. In this paper, we show how these bisimulation proof methods can be adapted to psi-calculi. We formalise all our definitions and theorems in Nominal Isabelle, and show examples where the use of up to-techniques yields drastically simplified proofs of known results. We also prove new structural laws about the replication operator.

    Place, publisher, year, edition, pages
    New York: ACM Press, 2016
    Keywords
    Bisimulation up-to, process calculus, psi-calculi, Isabelle, Nominal Isabelle, nominal logic
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-229008 (URN)10.1145/2854065.2854080 (DOI)000389021600016 ()9781450341271 (ISBN)
    Conference
    CPP 2016, January 18–19, Saint Petersburg, FL
    Available from: 2016-01-18 Created: 2014-07-25 Last updated: 2018-01-11Bibliographically approved
    6. The Expressive Power of Monotonic Parallel Composition
    Open this publication in new window or tab >>The Expressive Power of Monotonic Parallel Composition
    2016 (English)In: Programming Languages and Systems, Berlin: Springer, 2016, p. 780-803Conference paper, Published paper (Refereed)
    Place, publisher, year, edition, pages
    Berlin: Springer, 2016
    Series
    Lecture Notes in Computer Science, ISSN 0302-9743 ; 9632
    National Category
    Computer Sciences
    Identifiers
    urn:nbn:se:uu:diva-297465 (URN)10.1007/978-3-662-49498-1_30 (DOI)000401936100030 ()978-3-662-49497-4 (ISBN)
    Conference
    ESOP 2016, April 3–7, Eindhoven, The Netherlands
    Available from: 2016-03-22 Created: 2016-06-23 Last updated: 2018-01-10Bibliographically approved
  • 72655.
    Åman Pohjola, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
    Verifying Psi-calculi2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Psi-calculi are mobile process calculi, parametrised with arbitrary nominal datatypes representing data, communication channels, assertions and conditions, as well as morphisms over those datatypes. The framework for psi-calculi has been formalised in the interactive theorem prover Isabelle, along with both strong and weak bisimulation.

    This master's thesis project presents a tool for formally verifying that psi-calculus candidates are well-defined within the Isabelle/HOL-Nominal framework. It employs custom-made, heuristic proof tactics that discharge as many proof obligations as possible automatically, and passes any remaining proof obligations back to the user, who must supply manual proofs. The implementation of the tool as well as the proof strategies employed are described. The tool is applied to verify encodings of both the monadic and polyadic variants of the pi-calculus, as well as the pi-F calculus.

  • 72656.
    Åman Pohjola, Johannes
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Borgström, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Raabjerg, Palle
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Rodhe, Ioana
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Negative premises in applied process calculi2013Report (Other academic)
  • 72657.
    Åman Pohjola, Johannes
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Bisimulation up-to techniques for psi-calculi2016In: Proc. 5th ACM SIGPLAN Conference on Certified Programs and Proofs / [ed] Avigad, J; Chlipala, A, New York: ACM Press, 2016, p. 142-153Conference paper (Refereed)
    Abstract [en]

    Psi-calculi is a parametric framework for process calculi similar to popular pi-calculus extensions such as the explicit fusion calculus, the applied pi-calculus and the spi calculus. Remarkably, machine-checked proofs of standard algebraic and congruence properties of bisimilarity apply to all calculi within the framework. Bisimulation up-to techniques are methods for reducing the size of relations needed in bisimulation proofs. In this paper, we show how these bisimulation proof methods can be adapted to psi-calculi. We formalise all our definitions and theorems in Nominal Isabelle, and show examples where the use of up to-techniques yields drastically simplified proofs of known results. We also prove new structural laws about the replication operator.

  • 72658.
    Åman Pohjola, Johannes
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Priorities Without Priorities: Representing Preemption in Psi-Calculi2014In: Proc. 21st International Workshop on Expressiveness in Concurrency, and 11th Workshop on Structural Operational Semantics, 2014, p. 2-15Conference paper (Refereed)
  • 72659.
    Åman Pohjola, Johannes
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    Parrow, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computing Science.
    The Expressive Power of Monotonic Parallel Composition2016In: Programming Languages and Systems, Berlin: Springer, 2016, p. 780-803Conference paper (Refereed)
  • 72660.
    Åman, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Understanding when customers leave: Defining customer health and how it correlates with software usage2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    More and more businesses today focus on building long-term customer relationships with the objective to secure recurring revenues in competitive markets. As a result, management philosophies such as Customer Success have emerged, which underlines the importance of knowing your customers in order to make them stay. A common way of tracking the well-being of a firm's customers is the use of customer health scores. Such tools monitor assembled data and indicate whether a customer is doing fine, or is in the risk zone of ending the business relationship. However, there exists little to no consensus on what customer health actually means, or how to distinguish suitable parameters for measuring this concept. Therefore, the purpose of this thesis has been:

    To extend the existing knowledge of the business concept customer health, and show how to identify relevant parameters for measuring customer health.

    To reach this purpose, a study has been conducted at a software-as-a-service company operating in the field of digital marketing; where methods such as semi-structured interviews, ethnography, web survey, data mining execution and statistical analysis have been used. The results show that software usage differs between active and former customers, with the general tendency that a high software usage indicates a higher propensity to stay as a customer. The study concludes that customer health is best defined as "the perceived value a customer experiences when using a product". In addition, the parameters that were found to best indicate customer health at the company studied were linked to customers’ software usage as well as their marketing set-up.

  • 72661.
    Åmand, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Ammonium Feedback Control in Wastewater Treatment Plants2014Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The aeration process is often the single largest consumer of electricity in a wastewater treatment plant. Aeration in biological reactors provides microorganisms with oxygen which is required to convert ammonium to nitrate. Ammonium is toxic for aqueous ecosystems and contributes to eutrophication. The importance of aeration for the treatment results in combination with the high costs motivates automatic control of the aeration process.

    This thesis is devoted to ammonium feedback control in municipal wastewater treatment plants. With ammonium feedback control, the aeration intensity is changed based on a measurement of the outlet ammonium concentration. The main focus of the thesis is design, implementation, evaluation and improvement of ammonium PI (proportional-integral) controllers.

    The benefits of ammonium feedback control are established through long-term experiments at three large wastewater treatment plants in Stockholm, Sweden. With ammonium feedback control, energy savings up to around 10 % were achieved compared to keeping the dissolved oxygen concentration constant. The experiments generated several lessons learned with regard to implementation and evaluation of controllers in full-scale operation.

    The thesis has established guidelines on how to design ammonium feedback controllers for situations when cost-effective operation is the overall aim. Simulations have demonstrated the importance to limit the dissolved oxygen concentration in the process and under what conditions the energy saving with ammonium feedback control is large.

    The final part of the thesis treats improvements of ammonium PI control through minor modifications to the control structure or controller. Three strategies were studied: gain scheduling control, repetitive control, and a strategy reacting to oxygen peaks in the last aerobic zone. The strategies all had their benefits but the ammonium feedback controller was the key factor to improved aeration control.

  • 72662.
    Åmand, Linda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    A regional Swedish consortium for research and education: Demand-driven research within wastewater and sludge management2010In: Proc. 2nd IWA Water and Energy Conference, International Water Association , 2010, p. 100-101Conference paper (Refereed)
  • 72663.
    Åmand, Linda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Energy efficient ammonium feedback control2012In: New Developments in IT & Water, 2012Conference paper (Refereed)
    Abstract [en]

    Ammonium feedback control is increasingly used to determine the dissolved oxygen set-point in aerated activated sludge processes. This study compare ammonium feedback control with different controller settings to constant dissolved oxygen control and a dissolved oxygen profile created by minimising the air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily flow proportional average concentration. The influent included daily variations only, and comparisons are performed at different plant loads. The results suggest that ammonium feedback control can achieve close to optimal performance if a near proportional controller based on the in-situ ammonium concentration is used. Compared to constant oxygen concentration the best performing ammonium controller can achieve a 2.5 – 3.5 % savings in the air flow rate, while the optimal solution can achieve a 3 – 4 % saving.

  • 72664.
    Åmand, Linda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Learning control applied to continuous wastewater treatment systems: an initial study2010In: Proc. 2nd IWA Water and Energy Conference, International Water Association , 2010, p. 98-99Conference paper (Refereed)
  • 72665.
    Åmand, Linda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Optimal aeration control in a nitrifying activated sludge process2012In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 46, no 7, p. 2101-2110Article in journal (Refereed)
  • 72666. Åmand, Linda
    et al.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    The optimal dissolved oxygen profile in a nitrifying activated sludge process: comparisons with ammonium feedback control2013In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 68, no 3, p. 641-649Article in journal (Refereed)
    Abstract [en]

    Ammonium feedback control is increasingly used to determine the dissolved oxygen (DO) set-point in aerated activated sludge processes for nitrogen removal. This study compares proportional-integral (PI) ammonium feedback control with a DO profile created from a mathematical minimisation of the daily air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily average concentration. The influent includes daily variations only and the model has three aerated zones. Comparisons are made at different plant loads and DO concentrations, and the placement of the ammonium sensor is investigated. The results show that ammonium PI control can achieve the best performance if the DO set-point is limited at a maximum value and with little integral action in the controller. Compared with constant DO control the best-performing ammonium controller can achieve 1-3.5% savings in the air flow rate, while the optimal solution can achieve a 3-7% saving. Energy savings are larger when operating at higher DO concentrations.

  • 72667.
    Åmand, Linda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Laurell, C.
    Stark-Fujii, K.
    Thunberg, A.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Lessons learnt from evaluating full-scale ammonium feedback control in three large wastewater treatment plants2014In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 69, no 7, p. 1573-1580Article in journal (Refereed)
    Abstract [en]

    Three large wastewater treatment plants in Sweden participate in a project evaluating different types of ammonium feedback controllers in full-scale operation. The goal is to improve process monitoring, maintain effluent water quality and save energy. The paper presents the outcome of the long-term evaluation of controllers. Based on the experiences gained from the full-scale implementations, a discussion is provided about energy assessment for the purpose of comparing control strategies. The most important conclusions are the importance of long-term experiments and the difficulty of comparing energy consumption based on air flow rate measurements.

  • 72668. Åmand, Linda
    et al.
    Nygren, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Applications of repetitive control in activated sludge processes2011Conference paper (Other academic)
  • 72669. Åmand, Linda
    et al.
    Olsson, Gustaf
    Carlsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Aeration control: a review2013In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 67, no 11, p. 2374-2398Article, review/survey (Refereed)
    Abstract [en]

    This review covers automatic control of continuous aeration systems in municipal wastewater treatment plants. The review focuses on published research in the 21st century and describes research into various methods to decide and control the dissolved oxygen (DO) concentration and to control the aerobic volume with special focus on plants with nitrogen removal. Important aspects of control system implementation and success are discussed, together with a critical review of published research on the topic. With respect to DO control and determination, the strategies used for control span from modifications and developments of conventional control methods which have been explored since the 1970s, to advanced control such as model-based predictive and optimal controllers. The review is supplemented with a summary of comparisons between control strategies evaluated in full-scale, pilot-scale and in simulations.

  • 72670.
    Ån, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Mickelsson, Lovisa
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Sanderyd, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Sedvall, Emelie
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Posluk, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Sener, Kerime
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Processutrustning och laboratorieplanering2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 72671.
    Ångman, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Industrial Engineering & Management.
    Kartläggning och utvärdering av produkter och tjänster kopplat till begreppet Smart Grids2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Smart Grids development is driven by forces concerning safe electric

    transmission done in an energy efficient way. Vattenfall Eldistribution AB has a vision

    to transform their electricity network into Smart Grids. To invest in Smart Grids they

    have a need to show their customers what advantages they will get from the

    development. This led to the formulation of this dissertation project where the aim is

    to identify products and services related to Smart Grids that will increase the

    customer satisfaction for Vattenfall Eldistributions private customers.

    The project started with a mapping of existing products and services on the Swedish

    electricity market. From the mapping several development possibilities for Vattenfall

    Eldistribution were identified. Two of these development possibilities where analyzed

    more deeply as they seemed to have a grate possibility to fulfil the aim of the project.

    The two services that where studied more closely were follow-up on new electricity

    connections and an electricity usage report. The two services where analyzed from a

    market, organisation and strategy perspective.

    The findings from this study show that Vattenfall Eldistribution should introduce an

    electricity usage report for their private customers and that a pilot project should be

    carried out for follow-up on new electricity connections.

  • 72672.
    Ångman, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Ekologikunskaper hos blivande gymnasieelever: Skillnader i kunskapen hos sökanden till högskoleförberedande- och yrkesförberedande program2014Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna undersökning är att ta reda på vilka kunskaper inom ekologi högstadieelever har med sig till gymnasiet. Eftersom de flesta gymnasieprogram innefattar kurser i naturkunskap eller biologi så vill jag ta reda på vad man som gymnasielärare kan förvänta sig att de nya eleverna har med sig i bagaget. Ekologi och hållbar utveckling genomsyrar stor del av samhällsdebatten idag och det är en del av skolan uppdrag att ge eleverna möjligheter till att ta ansvar för miljön som de kan påverka. För att en gymnasielärare ska kunna fortsätta utveckla sina elever är det av stor vikt att veta vilka grundkunskaper eleverna bär med sig. Detta för att läraren ska kunna förbereda sin undervisning på bästa sätt för att eleverna ska kunna tillgodogöra sig denna.

    Jag har utfört en enkätundersökning med 100 elever i årskurs 9 i närförort till en större stad. Hälften av deltagarna avsåg att välja ett högskoleförberedande program och hälften ett yrkesförberedande program. En hypotes är att eleverna som väljer högskoleförberedande respektive yrkesförberedande program i gymnasiet kan ha olika grad av studiemotivation vilket skulle kunna visa sig i eventuella skillnader mellan de två undersökningsgrupperna i den kvalitativa kunskapen de bär med sig.

    Resultaten visade att det inte var någon större skillnad i kvalitativa kunskaper mellan de två undersökningsgrupperna, men det fanns en signifikant skillnad i svarssäkerheten mellan grupperna. Ett annat resultat av studien var att eleverna har med sig godkända kunskapskrav i ämnet biologi men saknar en förståelse för materiens kretslopp.

  • 72673.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Hydrogen absorption/desorption properties of the Sc(AlxNi1-x)2 system2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sc(AlxNi1-x)2 is a pseudobinary C14 Laves phase and a potential interstitial hydrogen storage material or anode in a Ni-MH battery. A previous study showed that Sc1Al1Ni1 can store hydrogen reversibly; both interstitially and trough decomposition into ScH2 and AlNi. It is also known that the exact composition is very important for the hydrogen storage properties of pseudobinary Laves phases. This thesis work is aimed at synthesising Sc(AlxNi1-x)2 and study the effect of the Ni/Al ratio on the hydrogen absorption/desorption process as well as the interstitial storage capacity. Compositions with high nickel content had the highest capacity (at least 0.67wt% for ScAl0.66Ni1.34) and ones with high aluminium content had the lowest total storage capacity (0wt% for ScAl1.28Ni0.62). The former composition was also shown to absorb and desorb hydrogen during multiple cycles. Desorption of interstitial hydrogen from ScAl0.66Ni1.34 requires 4.6kJ/mol in activation energy.

  • 72674.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Structural Basis for Hydrogen Interaction in Selected Metal Hydrides2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Metal hydrides have existing and potential uses in many applications such as in batteries, for hydrogen storage and for heat storage. New metal hydrides and a better understanding of the behaviour of known metal hydrides may prove crucial in the realisation or further development of these applications. The aims of the work described in this thesis have been to characterise new metal hydrides, investigate how the properties of known metal hydrides can be improved and understand how their structure influences these properties. Metal hydrides, in most cases synthesised via high-temperature techniques, were structurally characterised using X-ray powder diffraction, X-ray single crystal diffraction and neutron powder diffraction and their thermodynamic and kinetic properties by in-situ X-ray powder diffraction, thermal desorption spectroscopy and pressure-composition-temperature measurements.

    The investigations showed that: the storage capacity of the hexagonal Laves phase Sc(Al1-xNix)2 decreases with increasing Al content. There is a significant decrease in the stability of the hydrides and faster reaction kinetics when Zr content is increased in the cubic Laves phase Sc1-xZrx(Co1-xNix)2. Nb4M0.9Si1.1 (M=Co, Ni) form very stable interstitial hydrides which have very slow sorption kinetics. MgH2 mixed with 10 mol% ScH2 reaches full activation after only one cycle at 673 K while it takes at least four cycles at 593 K. LnGa (Ln=Nd, Gd) absorb hydrogen in two steps, it is very likely that the first step is interstitial solution of hydride ions into Ln4 tetrahedra and the second step places hydrogen atoms in Ln3Ga tetrahedra. The nature of the Ga-H bond is still unclear.

    List of papers
    1. Hydrogen absorption and desorption properties of a novel ScNiAl alloy
    Open this publication in new window or tab >>Hydrogen absorption and desorption properties of a novel ScNiAl alloy
    Show others...
    2011 (English)In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 104, no 1, p. 235-238Article in journal (Refereed) Published
    Abstract [en]

    A new hydrogen absorbing material has been discovered, ScNiAl, which can store 1.5 wt.% hydrogen reversibly. In this compound, hydrogen absorption is a two-step process; solid solution of hydrogen at temperatures below 180A degrees C and decomposition into ScH2 and NiAl at higher temperatures. Detailed analysis of the hydrogen absorption/desorption has been performed using in situ synchrotron radiation powder X-ray diffraction and thermal desorption spectroscopy. The apparent activation energy for hydrogen desorption was determined to be 182 kJ/mol and the material is stable during cycling.

    National Category
    Natural Sciences Inorganic Chemistry
    Research subject
    Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-156009 (URN)10.1007/s00339-010-6116-z (DOI)000291652600034 ()
    Available from: 2011-07-05 Created: 2011-07-05 Last updated: 2017-12-11Bibliographically approved
    2. Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)2
    Open this publication in new window or tab >>Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)2