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  • 13251. Öjerskog,
    Utformning av miljömässiga nyckeltal och en bedömningsmall för miljöaspekter på Umeå Energi AB2006Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 13252.
    Ölund, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Jämförelse av olika metoder att generera Bernoullifördelade slumptal givet deras summa2000Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this master’s thesis the problem of simulating conditional Bernoulli distributed stochastic variables, given the sum, is considered. Three simulation methods are considered, namely the acceptance/rejection technique, Bondesson’s method and the Markov chain Monte Carlo method.

    To compare the three methods the bias and the standard deviations of the simulated variables are evaluated. The results of the simulation study shows that the Markov chain Monte Carlo method is not the best method for this type of simulation. Both the other methods were quite suitable for the task. The acceptance/rejection technique is a little bit more time consuming than Bondesson’s method, but on the other hand the acceptance/rejection technique is easier to implement.

  • 13253.
    Ölund, Marie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Att utveckla lärandet i matematik: En studie i hur lärare genom sin undervisning utvecklar elevers lärande i grundskolans tidigare år2016Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The most important influencing factor in student learning is the teacher. It is not so much what the teacher does, but what the teacher makes his students to do that is important. That is what this study investigates. Which workingmethods are used and how are they varied? It also investigates how formative assessment is used in practice. Which formative elements can be found in the teachers practice and what methods are used? As data collection methods interviews, classroom observations and a student questionare have been used. The results shows that teachers who vary their working methods and who use interactive methods have more positive pupils. The result also shows that the teachers use formative assessment but in varied extent. No teaching method can safely be said to be the best but one thing is certain - varied teaching promotes pupils learning!

  • 13254.
    Öman, Tommy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Multivariate Analysis of 2D-NMR Spectroscopy: Applications in wood science and metabolomics2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Wood is our most important renewable resource. We need better quality and quantity both according to the wood itself and the processes that are using wood as a raw material. Hence, the understanding of the chemical composition of the wood is of high importance. Improved and new methods for analyzing wood are important to achieve better knowledge about both refining processes and raw material. The combination of NMR and multivariate analyses (MVA) is a powerful method for these analyses but so far it has been limited mainly to 1D NMR. In this project, we have developed methods for combining 2D NMR and MVA in both wood analysis and metabolomics. This combination was used to compare samples from normal wood and tension wood, and also trees with a down regulation of a pectin responsible gene. Dissolving pulp was also examined using the same combination of 2D-NMR and MVA, together with FT-IR and solid state 13C CP-MAS NMR. Here we focused on the difference between wood type (softwood and hardwood), process type (sulfite and sulfate) and viscosity. These methods confirmed and added knowledge about the dissolving pulp. Also reactivity was compared in relation to morphology of the cellulose and pulp composition. Based on the method and software used in the wood analysis projects, a new method called HSQC-STOCSY was developed. This method is especially suited for assignment of substances in complex mixtures. Peaks in 2D NMR spectra that correlate between different samples are plotted in correlation plots resembling regular NMR spectra. These correlation plots have great potential in identifying individual components in complex mixtures as shown here in a metabolic data set. This method could potentially also be used in other areas such as drug/target analyses, protein dynamics and assignment of wood spectra.

  • 13255.
    Öman, Tommy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Reactivity of dissolving pulp analyzed with multivariate data analysis of XRD and NMR data.Manuskript (preprint) (Övrigt vetenskapligt)
  • 13256.
    Öman, Tommy
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tessem, Maj-Britt
    Bathen, Tone F
    Bertilsson, Helena
    Angelsen, Anders
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Andreassen, Trygve
    Identification of metabolites from 2D 1H-13C HSQC NMR using peak correlation plots2014Ingår i: BMC Bioinformatics, ISSN 1471-2105, E-ISSN 1471-2105, Vol. 15, artikel-id 413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Identification of individual components in complex mixtures is an important and sometimes daunting task in several research areas like metabolomics and natural product studies. NMR spectroscopy is an excellent technique for analysis of mixtures of organic compounds and gives a detailed chemical fingerprint of most individual components above the detection limit. For the identification of individual metabolites in metabolomics, correlation or covariance between peaks in 1H NMR spectra has previously been successfully employed. Similar correlation of 2D 1H-13C Heteronuclear Single Quantum Correlation spectra was recently applied to investigate the structure of heparine. In this paper, we demonstrate how a similar approach can be used to identify metabolites in human biofluids (post-prostatic palpation urine).

    Results: From 50 1H-13C Heteronuclear Single Quantum Correlation spectra, 23 correlation plots resembling pure metabolites were constructed. The identities of these metabolites were confirmed by comparing the correlation plots with reported NMR data, mostly from the Human Metabolome Database.

    Conclusions: Correlation plots prepared by statistically correlating 1H-13C Heteronuclear Single Quantum Correlation spectra from human biofluids provide unambiguous identification of metabolites. The correlation plots highlight cross-peaks belonging to each individual compound, not limited by long-range magnetization transfer as conventional NMR experiments.

  • 13257.
    Önskog, Jenny
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Freyhult, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Landfors, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi, Klinisk bakteriologi.
    Rydén, Patrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Hvidsten, Torgeir R
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Classification of microarrays: synergistic effects between normalization, gene selection and machine learning2011Ingår i: BMC Bioinformatics, ISSN 1471-2105, E-ISSN 1471-2105, Vol. 12, nr 1, artikel-id 390Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND: Machine learning is a powerful approach for describing and predicting classes in microarray data. Although several comparative studies have investigated the relative performance of various machine learning methods, these often do not account for the fact that performance (e.g. error rate) is a result of a series of analysis steps of which the most important are data normalization, gene selection and machine learning.

    RESULTS: In this study, we used seven previously published cancer-related microarray data sets to compare the effects on classification performance of five normalization methods, three gene selection methods with 21 different numbers of selected genes and eight machine learning methods. Performance in term of error rate was rigorously estimated by repeatedly employing a double cross validation approach. Since performance varies greatly between data sets, we devised an analysis method that first compares methods within individual data sets and then visualizes the comparisons across data sets. We discovered both well performing individual methods and synergies between different methods.

    CONCLUSION: Support Vector Machines with a radial basis kernel, linear kernel or polynomial kernel of degree 2 all performed consistently well across data sets. We show that there is a synergistic relationship between these methods and gene selection based on the T-test and the selection of a relatively high number of genes. Also, we find that these methods benefit significantly from using normalized data, although it is hard to draw general conclusions about the relative performance of different normalization procedures.

  • 13258.
    Önskog, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Invariant Pseudodistances and Pseudometrics in Complex Analysis in Several Variables2003Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    At present time invariant pseudodistances and pseudometrics pose an important tool in complex analysis in several variables. This thesis is mainly devoted to giving a thorough definition of these objects and in particular to Schwarz-Pick systems such as the Carathéodory and Kobayashi pseudodistances.

    Most basic properties, such as continuity and boundary behaviour, of the Carathéodory and Kobayashi pseudo-distances and pseudometrics are investigated. As an application of the theory, the thesis is concluded with a proof of the biholomorphic inequivalence between the unit ball and unit polydisc in Cn.

  • 13259.
    Önskog, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    The Skorohod problem and weak approximation of stochastic differential equations in time-dependent domains2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis consists of a summary and four scientific articles. All four articles consider various aspects of stochastic differential equations and the purpose of the summary is to provide an introduction to this subject and to supply the notions required in order to fully understand the articles.

    In the first article we conduct a thorough study of the multi-dimensional Skorohod problem in time-dependent domains. In particular we prove the existence of cádlág solutions to the Skorohod problem with oblique reflection in time-independent domains with corners. We use this existence result to construct weak solutions to stochastic differential equations with oblique reflection in time-dependent domains. In the process of obtaining these results we also establish convergence results for sequences of solutions to the Skorohod problem and a number of estimates for solutions, with bounded jumps, to the Skorohod problem.

    The second article considers the problem of determining the sensitivities of a solution to a second order parabolic partial differential equation with respect to perturbations in the parameters of the equation. We derive an approximate representation of the sensitivities and an estimate of the discretization error arising in the sensitivity approximation. We apply these theoretical results to the problem of determining the sensitivities of the price of European swaptions in a LIBOR market model with respect to perturbations in the volatility structure (the so-called ‘Greeks’).

    The third article treats stopped diffusions in time-dependent graph domains with low regularity. We compare, numerically, the performance of one adaptive and three non-adaptive numerical methods with respect to order of convergence, efficiency and stability. In particular we investigate if the performance of the algorithms can be improved by a transformation which increases the regularity of the domain but, at the same time, reduces the regularity of the parameters of the diffusion.

    In the fourth article we use the existence results obtained in Article I to construct a projected Euler scheme for weak approximation of stochastic differential equations with oblique reflection in time-dependent domains. We prove theoretically that the order of convergence of the proposed algorithm is 1/2 and conduct numerical simulations which support this claim.

  • 13260.
    Önskog, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Nyström, Kaj
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Pricing and hedging of financial derivatives using a posteriori error estimates and adaptive methods for stochastic differential equations2010Ingår i: Journal of Computational and Applied Mathematics, ISSN 0377-0427, E-ISSN 1879-1778, Vol. 235, s. 563-592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The efficient and accurate calculation of sensitivities of the price of financial derivatives with respect to perturbations of the parameters in the underlying model, the so-called `Greeks', remains a great practical challenge in the derivative industry. This is true regardless of whether methods for partial differential equations or stochastic differential equations (Monte Carlo techniques) are being used. The computation of the `Greeks' is essential to risk management and to the hedging of financial derivatives and typically requires substantially more computing time as compared to simply pricing the derivatives. Any numerical algorithm (Monte Carlo algorithm) for stochastic differential equations produces a time-discretization error and a statistical error in the process of pricing financial derivatives and calculating the associated `Greeks'. In this article we show how a posteriori error estimates and adaptive methods for stochastic differential equations can be used to control both these errors in the context of pricing and hedging of financial derivatives. In particular, we derive expansions, with leading order terms which are computable in a posteriori form, of the time-discretization errors for the price and the associated `Greeks'. These expansions allow the user to simultaneously first control the time-discretization errors in an adaptive fashion, when calculating the price, sensitivities and hedging parameters with respect to a large number of parameters, and then subsequently to ensure that the total errors are, with prescribed probability, within tolerance.

  • 13261.
    Önskog, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Nyström, Kaj
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    The Skorohod oblique reflection problem in time-dependent domains2010Ingår i: Annals of Probability, ISSN 0091-1798, E-ISSN 2168-894X, Vol. 38, nr 6, s. 2170-2223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The deterministic Skorohod problem plays an important role in the construction and analysis of diffusion processes with reflection. In the form studied here, the multidimensional Skorohod problem was introduced, in time-independent domains, by H. Tanaka and further investigated by P.-L. Lions and A.-S. Sznitman in their celebrated article. Subsequent results of several researchers have resulted in a large literature on the Skorohod problem in time-independent domains. In this article we conduct a thorough study of the multidimensional Skorohod problem in time-dependent domains. In particular, we prove the existence of càdlàg solutions (x, λ) to the Skorohod problem, with oblique reflection, for (D,,w) assuming, in particular, that D is a time-dependent domain (Theorem 1.2). In addition, we prove that if w is continuous, then x is continuous as well (Theorem 1.3). Subsequently, we use the established existence results to construct solutions to stochastic differential equations with oblique reflection (Theorem 1.9) in time-dependent domains. In the process of proving these results we establish a number of estimates for solutions to the Skorohod problem with bounded jumps and, in addition, several results concerning the convergence of sequences of solutions to Skorohod problems in the setting of time-dependent domains.

  • 13262.
    Önskog, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Nyström, Kaj
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Weak approximation of obliquely reflected diffusions in time-dependent domains2010Ingår i: Journal of Computational Mathematics, ISSN 0254-9409, E-ISSN 1991-7139, Vol. 28, nr 5, s. 579-605Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In an earlier paper, we proved the existence of solutions to the Skorohod problem with oblique reflection in time-dependent domains and, subsequently, applied this result to the problem of constructing solutions, in time-dependent domains, to stochastic differential equations with oblique reflection. In this paper we use these results to construct weak approximations of solutions to stochastic differential equations with oblique reflection, in time-dependent domains in R^d, by means of a projected Euler scheme. We prove that the constructed method has, as is the case for normal reflection and time-independent domains, an order of convergence equal to 1/2 and we evaluate the method empirically by means of two numerical examples. Furthermore, using a well-known extension of the Feynman-Kac formula, to stochastic differential equations with reflection, our method gives, in addition, a Monte Carlo method for solving second order parabolic partial differential equations with Robin boundary conditions in time-dependent domains.

  • 13263.
    Öquist, Gunnar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Effects of low temperature on photosynthesis1983Ingår i: Plant, Cell and Environment, ISSN 0140-7791, E-ISSN 1365-3040, Vol. 6, nr 4, s. 281-300Artikel, forskningsöversikt (Refereegranskat)
  • 13264.
    Öqvist, Annafia
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Hemkompost: en utvärdering av etapp 1 i UMEVA:s projekt för återvinning av matavfall i Umeå kommun2008Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 13265. Örberg, Håkan
    et al.
    Jansson, Stina
    Kalén, Gunnar
    Thyrel, Mikael
    Xiong, Shaojun
    Combustion and Slagging Behavior of Biomass Pellets Using a Burner Cup Developed for Ash-Rich Fuels2014Ingår i: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 28, nr 2, s. 1103-1110Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An innovative pellet burner cup (“BTC burner”) designed to enable the burning of ash-rich fuels in small-scale boilers (30–40 kW) was evaluated, with respect to slagging behavior, combustion performance, and flue gas composition. The BTC burner features an open, flat-bottomed channel with air supply tubes on top of its lateral sides. The pellets are fed in horizontally, pushing the formed ash forward until it drops down into the ash pan. Eight different pelletized biomass fuels were combusted in the BTC burner, and no unscheduled stops occurred during the combustion tests. Conversely, seven of the eight fuel assortments caused unscheduled stops, because of slagging and/or piling-up of ash when burned in a conventional underfeed burner. The level of slagging in the BTC burner was considerably lower than in the underfeed burner, and the slag and ash were transported out of the burner cup without any complications. Combustion in the BTC burner cup also produced lower CO concentrations in the flue gas for all significantly sintering wood fuels and reed canary grass, and reduced NO emissions for all but one of the studied fuels. However, the BTC burner produced higher NO2 and SO2 levels than the underfeed burner for most assortments, and higher CO concentrations when burning corn stover with or without added lime. Further optimization of the BTC design will be required, particularly in order to minimize particle emissions.

  • 13266.
    Örberg, Håkan
    et al.
    Sveriges Lantbruksuniversitet, Enheten för Biomassateknologi och Kemi.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Grimm, Alejandro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Boström, Dan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik, Energiteknik och termisk processkemi.
    Öhman, Marcus
    Teknikutveckling för ökad etablering och nyttjande av rörflen: Demonstrationsförsök i fullskala2010Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Resultaten visar att energigräset rörflen kan utgöra ett kompletterande bränsle till det skogsbränsle och den torv som idag används i svenska värme- och kraftvärmeanläggningar. En inblandning av rörflen med ca 10 % på energibasis i en bränslemix som för övrigt består av 10-20 % carextorv och 70-80 % träbränsle har i demonstrationsförsök visat goda resultat. Denna bränslemix har vid fullskaliga förbränningsförsök i fluidiserande bädd (Hedensbyn,CFB 98 MW) under sammanlagt 4 dygn inte gett upphov till störningar eller negativa effekter på utrustning eller ökade utsläpp i rökgaserna i form av partiklar eller gasformiga emissioner. Vid simulerade påverkan på överhettare i form av kylda sonder har även konstaterats att beläggningstillväxten varit oförändrad och ej givit upphov till ökad korrosion.

    Inblandning i bränslemixen har skett med hackad rörflen (40-50 mm) i torvdelen för att en jämn inblandning kunde åstadkommas. Rörflensmaterialet har levererats i samband med skörden så att det hackats direkt på fältet med exakthack kopplad till vagn eller med containerhantering. Vid leverans under vår och försommar har rörflenen hållit mycket låg fukthalt med ett medel på 11,3 % fukt. Jämförande studier har gjorts med system där rörflen vid skörden under vår pressats till storbalar för vidare transport till terminal eller gårdscentrum. Detta system har visat sig mindre effektivt jämfört med direkthackning på fältet och transport av hackat material till värmeverk. En fördel med storbalssystemet är dock att det möjliggör mer kostnadseffektiv lagring utan att t.ex. fukthalten höjs under lagringstiden. Även vägtransport från terminal eller gårdscentrum till värmeverk har visat sig mer effektivt med storbalar jämfört med hackat material. Vid lastning av stora fyrkantsbalar (90x120x220 cm) på lastbil med släp uppnåddes i stort sett dubbla lastvikten jämfört med hackad rörflen (20,9 ton jmf. m. 11,0 ton).

    För de något mindre anläggningarna av typen rosterpannor som provats (0,6 och 4 MW) har den briketterade formen av rörflen använts för att uppnå en jämn och koncentrerad bränslematning. Även här har en blandning av rörflen och torv visat sig användbar och speciellt för rörflen med låg askhalt har torvinblandning på 15 vikts-% av gett minskad tendens till sintring av askan. Rörflen med hög askhalt (utan torvinblandning) har kunnat sameldas med träbränsle utan risk för sintrad aska i dessa anläggningar. Tillverkningen av briketter för försöken, sammanlagt ca 35 ton, varav hälften med inblandning av torv har genomförts utan störningar och med bra kvalité på briketterna.

  • 13267.
    Öredal, Therese
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Verksamhetsutövares egenkontroll av oljeavskiljare: Finns det brister, vilka krav kan tillsynsmyndigheten ställa samt vad kan verksamhetsutövare förbättra?2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this report was to investigate whether operators, in the municipality of Örnsköldsvik, comply to current regulations and guidelines regarding oil separator. In addition to this, the report also identify which standards the regulatory authority can demand of identified deficiencies, as well as an examination in how the status of oil separator are in other municipalities in Sweden. First a delimitation was made to only investigate environmentally hazardous activities such as haulage contractors. Inventories were made of a total of 12 haulage contractors, with questions from a previously made checklist. The results of the inventory indicated deficiencies in operators existing knowledge, regular self-inspection of oil separators, control frequency, record-keeping and documentation, lack of 5-year inspection and lack of oil- and sludge level alarm. This report also shows that regulatory authority can require the operators to rectify these deficiencies, in accordance with standards and established guidelines. The report also showed similar results when compared with similar surveys of operators' self-inspection of oil separator, in other municipalities in Sweden. The study suggests that regulatory authority should priority to oversight these environmentally hazardous activities with oil separators.

  • 13268.
    Örnmark, Jannice
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Utvärdering och optimering av en biologisk fosforavskiljningsprocess vid Duvbackens reningsverk.Mikrobiologiska, processtekniska och externa aspekter2007Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 13269.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A model for simulation of application and resource behavior in heterogeneous distributed computing environments2012Ingår i: Proceedings of the 2nd international conference on simulation and modeling methodologies, technologies and applications / [ed] Nuno Pina, Janusz Kacprzyk, Mohammad S. Obaidat, SciTePress, 2012, s. 144-151Konferensbidrag (Refereegranskat)
  • 13270.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Barry, McCollum
    Queens University of Belfast, United Kingdom.
    Heuristics and Algorithms for Data Center Optimization2015Ingår i: Proceedings of the 7th Multidisciplinary International Conference on Scheduling : Theory and Applications (MISTA 2015) / [ed] Zdenek Hanzálek, Graham Kendall, Barry McCollum, Premysl Šůcha, 2015, s. 921-927Konferensbidrag (Övrigt vetenskapligt)
  • 13271.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Byrne, James
    Casari, Paolo
    Eardley, Philip
    Fernandez Anta, Antonio
    Forsman, Johan
    Kennedy, John
    Le Duc, Thang
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Noya Marino, Manuel
    Loomba, Radhika
    Lopez Pena, Miguel Angel
    Veiga, Jose Lopez
    Lynn, Theo
    Mancuso, Vincenzo
    Svorobej, Sergej
    Torneus, Anders
    Wesner, Stefan
    Willis, Peter
    Domaschka, Joerg
    Reliable Capacity Provisioning for Distributed Cloud/Edge/Fog Computing Applications2017Ingår i: 2017 EUROPEAN CONFERENCE ON NETWORKS AND COMMUNICATIONS (EUCNC), IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The REliable CApacity Provisioning and enhanced remediation for distributed cloud applications (RECAP) project aims to advance cloud and edge computing technology, to develop mechanisms for reliable capacity provisioning, and to make application placement, infrastructure management, and capacity provisioning autonomous, predictable and optimized. This paper presents the RECAP vision for an integrated edge-cloud architecture, discusses the scientific foundation of the project, and outlines plans for toolsets for continuous data collection, application performance modeling, application and component auto-scaling and remediation, and deployment optimization. The paper also presents four use cases from complementing fields that will be used to showcase the advancements of RECAP.

  • 13272.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    A Performance Evaluation of the Grid Job Management Framework (GJMF)2011Konferensbidrag (Refereegranskat)
  • 13273.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Decentralized Prioritization-Based Management Systems for Distributed Computing2013Ingår i: 2013 IEEE 9th international conference on e-science (e-science), IEEE Computer Society, 2013, s. 228-237Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fairshare scheduling is an established technique to provide user-level differentiation in management of capacity consumption in high-performance and grid computing scheduler systems. In this paper we extend on a state-of-the-art approach to decentralized grid fairshare and propose a generalized model for construction of decentralized prioritization-based management systems. The approach is based on (re) formulation of control problems as prioritization problems, and a proposed framework for computationally efficient decentralized priority calculation. The model is presented along with a discussion of application of decentralized management systems in distributed computing environments that outlines selected use cases and illustrates key trade-off behaviors of the proposed model.

  • 13274.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    GJMF - a composable service-oriented Grid job management framework2013Ingår i: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 29, nr 1, s. 144-157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate best practices for Grid software design and development, and propose a composable, loosely coupled Service-Oriented Architecture for Grid job management. The architecture focuses on providing a transparent Grid access model for concurrent use of multiple Grid middlewares and aims to decouple Grid applications from Grid middlewares and infrastructure. The notion of an ecosystem of Grid infrastructure components is extended, and Grid job management software design is discussed in this context. Non- intrusive integration models and abstraction of Grid middleware function- ality through hierarchical aggregation of autonomous Grid job management services are emphasized, and service composition techniques facilitating this process are explored. A proof-of-concept implementation of the architecture is presented along with a discussion of architecture implementation details and trade-offs introduced by the service composition techniques used.

  • 13275.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Increasing flexibility and abstracting complexity in service-based Grid and cloud software2011Ingår i: Proceedings of the 1st International Conference on Cloud Computing and Services Science / [ed] F. Leyman, I. Ivanov, M. van Sinderen and B. Shishkov, SciTePress, 2011, s. 240-249Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work addresses service-based software development in Grid and Cloud computing environments, and proposes a methodology for Service-Oriented Architecture design. The approach consists of an architecture design methodology focused on facilitating system flexibility, a service model emphasizing component modularity and customization, and a development tool designed to abstract service development complexity. The approach is intended for use in computational eScience environments and is designed to increase flexibility in system design, development, and deployment, and reduce complexity in system development and administration. To illustrate the approach we present case studies from two recent Grid infrastructure software development projects, and evaluate impact of the development approach and the toolset on the projects.

  • 13276.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Mediation of service overhead in service-oriented grid architectures2011Ingår i: 2011 IEEE/ACM 12th International Conference on Grid Computing, IEEE, 2011, s. 9-18Konferensbidrag (Refereegranskat)
    Abstract [en]

    Grid computing applications and infrastructures build heavily on Service-Oriented Computing development methodology and are often realized as Service-Oriented Architectures. The Grid Job Management Framework (GJMF) is a flexible Grid infrastructure and application support tool that offers a range of abstractive and platform independent interfaces for middleware-agnostic Grid job submission, monitoring, and control. In this paper we use the GJMF as a test bed for characterization of Grid Service-Oriented Architecture overhead, and evaluate the efficiency of a set of design patterns for overhead mediation mechanisms featured in the framework.

  • 13277.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Espling, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Decentralized scalable fairshare scheduling2013Ingår i: Future generations computer systems, ISSN 0167-739X, E-ISSN 1872-7115, Vol. 29, nr 1, s. 130-143Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work addresses Grid fairshare allocation policy enforcement and presents Aequus, a decentralized system for Grid-wide fairshare job prioritization. The main idea of fairshare scheduling is to prioritize users with regard to predefined resource allocation quotas. The presented system builds on three contributions: a flexible tree-based policy model that allows delegation of policy definition, a job prioritization algorithm based on local enforcement of distributed fairshare policies, and a decentralized architecture for non-intrusive integration with existing scheduling systems. The system supports organization of users in virtual organizations and divides usage policies into local and global policy components that are defined by resource owners and virtual organizations. The architecture realization is presented in detail along with an evaluation of the system behavior in an emulated environment. In the evaluation, convergence noise types (mechanisms counteracting policy allocation convergence) are characterized and quantified, and the system is demonstrated to meet scheduling objectives and perform scalably under realistic operating conditions.

  • 13278.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Groenda, Henning
    Wesner, Stefan
    Byrne, James
    Nikolopoulos, Dimitris S.
    Sheridan, Craig
    Krzywda, Jakub
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Ali-Eldin, Ahmed
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Tordsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Stier, Christian
    Krogmann, Klaus
    Domaschka, Jörg
    Hauser, Christopher B.
    Byrne, PJ
    Svorobej, Sergej
    McCollum, Barry
    Papazachos, Zafeiros
    Whigham, Darren
    Rüth, Stefan
    Paurevic, Dragana
    The CACTOS Vision of Context-Aware Cloud Topology Optimization and Simulation2014Ingår i: 2014 IEEE 6th International Conference on Cloud Computing Technology and Science, 2014, s. 26-31Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recent advances in hardware development coupled with the rapid adoption and broad applicability of cloud computing have introduced widespread heterogeneity in data centers, significantly complicating the management of cloud applications and data center resources. This paper presents the CACTOS approach to cloud infrastructure automation and optimization, which addresses heterogeneity through a combination of in-depth analysis of application behavior with insights from commercial cloud providers. The aim of the approach is threefold: to model applications and data center resources, to simulate applications and resources for planning and operation, and to optimize application deployment and resource use in an autonomic manner. The approach is based on case studies from the areas of business analytics, enterprise applications, and scientific computing.

  • 13279.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellander, Andreas
    Drawert, Brian
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Holmgren, Sverker
    Petzold, Linda
    Abstractions for scaling escience applications to distributed computing environments: a StratUm Integration Case Study in Molecular Systems Biology2012Ingår i: Bioinformatics: proceedings of the international conference on bioinformatics models, methods and algorithms / [ed] Correia, C; Fred, A; Gamboa, H; Schier, J, SETUBAL: SCITEPRESS , 2012, s. 290-294Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Management of eScience computations and resulting data in distributed computing environments is complicated and often introduces considerable overhead. In this work we address a lack of integration tools that provide the abstraction levels, performance, and usability required to facilitate migration of eScience applications to distributed computing environments, In particular, we explore an approach to raising abstraction levels based on separation of computation design computation management and present StratUm, a computation enactment tool for distributed computing environments. Results are illustrated in a case study of integration of a software from the systems biology community with a grid computation management system.

  • 13280.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellander, Andreas
    University of California, Santa Barbara, USA.
    Drawert, Brian
    University of California, Santa Barbara, USA.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Holmgren, Sverker
    Uppsala University, Sweden.
    Petzold, Linda
    University of California, Santa Barbara, USA.
    Reducing Complexity in Management of eScience Computation2012Ingår i: CCGrid 2012: Proceedings of the 12th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing / [ed] Balaji, P., Buyya, R., Majumdar, S., Pandey, S., IEEE, 2012, s. 845-852, artikel-id 6217522Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we address reduction of complexity in management of scientific computations in distributed computing environments. We explore an approach based on separation of computation design (application development) and distributed execution of computations, and investigate best practices for construction of virtual infrastructures for computational science - software systems that abstract and virtualize the processes of managing scientific computations on heterogeneous distributed resource systems. As a result we present StratUm, a toolkit for management of eScience computations. To illustrate use of the toolkit, we present it in the context of a case study where we extend the capabilities of an existing kinetic Monte Carlo software framework to utilize distributed computational resources. The case study illustrates a viable design pattern for construction of virtual infrastructures for distributed scientific computing. The resulting infrastructure is evaluated using a computational experiment from molecular systems biology.

  • 13281.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lockner, Niclas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Creo: reduced complexity service development2014Ingår i: Proceedings of CLOSER 2014 - 4th International Conference on Cloud Computing and Services Science / [ed] M. Helfert, F. Desprez, D. Ferguson, F. Leymann, V. Mendez Munoz, SciTePress, 2014, s. 230-241Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we address service-oriented software development in distributed computing environments, and investigate an approach to software development and integration based on code generation. The approach is illustrated in a toolkit for multi-language software generation built on three building blocks; a service description language, a serialization and transport protocol, and a set of code generation techniques. The approach is intended for use in the eScience domain and aims to reduce the complexity of development and integration of distributed software systems through a low-knowledge-requirements model for construction of network-accessible services. The toolkit is presented along with a discussion of use cases and a performance evaluation quantifying the performance of the toolkit against selected alternative techniques for code generation and service communication. In tests of communication overhead and response time, toolkit performance is found to be comparable to or improve upon the evaluated techniques.

  • 13282.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Lockner, Niclas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Reducing Complexity in Service Development and Integration2015Ingår i: Cloud computing and services sciences, CLOSER 2014, Springer Berlin/Heidelberg, 2015, s. 63-80Konferensbidrag (Refereegranskat)
    Abstract [en]

    The continuous growth and increasing complexity of distributed systems software has produced a need for software development tools and techniques that reduce the learning requirements and complexity of building distributed systems. In this work we address reduction of complexity in service-oriented software development and present an approach and a toolkit for multi-language service development based on three building blocks: a simplified service description language, an intuitive message serialization and transport protocol, and a set of code generation techniques that provide boilerplate environments for service implementations. The toolkit is intended for use in the eScience domain and is presented along with a performance evaluation that quantifies toolkit performance against that of selected alternative toolkits and technologies for service development. Toolkit performance is found to be comparable to or improve upon the performance of evaluated technologies.

  • 13283.
    Österberg, Sofia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Metabolism-dependent taxis and control of motility in Pseudomonas putida2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Bacteria living in soil and aquatic habitats rapidly adapt to changes in physico-chemical parameters that influence their energy status and thus their ability to proliferate and survive. One immediate survival strategy is to relocate to more metabolically optimal environments. To aid their movement through gradients (a process called taxis), many bacteria use whip like flagella organelles. Soil-dwelling Pseudomonas putida possesses a polar bundle of flagella that propel the bacterium forward in directed swimming motility. P. putida strains are generally fast growing, have a broad metabolic capacity, and are resistant to many harmful substances – qualities that make them interesting for an array of industrial and biotechnological application. This thesis identifies some of the factors that are involved in controlling the flagella driven motility of P. putida.

    In the first part of the thesis, I present evidence that P. putida displays energy-taxis towards metabolisable substrates and that the surface located Aer2 receptor (named after its similarities to the Escherichia coli Aer receptor) is responsible for detecting the changes in energy-status and oxygen-gradients that underlie this response. Aer2 is expressed simultaneously with the flagella needed for taxis responses and its expression is ensured during nutrient scares conditions through the global transcriptional regulators ppGpp and DksA.

    In addition to Aer2, P. putida possesses two more Aer-like receptors (Aer1 and Aer3) that are differentially expressed. Like Aer2, Aer1 and Aer3 co-localize to one cell pole. Although the signals to which Aer1 and Aer3 respond are unknown, analysis of Aer1 uncovered a role in motility control for a protein encoded within the same operon. This protein, called PP2258, instigated the work described in the second part of my thesis on the involvement of the second messenger c-di-GMP in regulation of P. putida motility. Genetic dissection of the catalytic activities of PP2258 revealed that it has the unusual capacity to both synthesize and degrade c-di-GMP. Coupling of the c-di-GMP signal originating from PP2258 to motility control was traced to the c-di-GMP binding properties of the protein PP4397. In the last part of the thesis, I present possible mechanisms for how these different components might interact to create a signal transduction cascade – from the surface located Aer1 receptor to PP2258 and the c-di-GMP responsive PP4397, and from there to the flagella motors – to ultimately determine flagella performance and the motility status of P. putida.

  • 13284.
    Österberg, Sofia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    del Peso-Santos, Teresa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Shingler, Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Regulation of alternative sigma factor use2011Ingår i: Annual Review of Microbiology, ISSN 0066-4227, E-ISSN 1545-3251, Vol. 65, s. 37-55Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alternative bacterial sigma factors bind the catalytic core RNA polymerase to confer promoter selectivity on the holoenzyme. The different holoenzymes are thus programmed to recognize the distinct promoter classes in the genome to allow coordinated activation of discrete sets of genes needed for adaptive responses. To form the holoenzymes, the different sigma factors must be available to compete for their common substrate (core RNA polymerase). This review highlights (a) the roles of antisigma factors in controlling the availability of alternative sigma factors and (b) the involvement of diverse regulatory molecules that promote the use of alternative sigma factors through subversion of the domineering housekeeping σ(70). The latter include the nucleotide alarmone ppGpp and small proteins (DksA, Rsd, and Crl), which directly target the transcriptional machinery to mediate their effects.

  • 13285.
    Österberg, Sofia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Skoog, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Shingler, Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    PP4397 provides the link between PP2258 c-di-GMP signalling and altered motility in Pseudomonas putidaManuskript (preprint) (Övrigt vetenskapligt)
  • 13286.
    Österberg, Sofia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Skärfstad, Eleonore
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Shingler, Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    The σ-factor FliA, ppGpp and DksA coordinate transcriptional control of the aer2 gene of Pseudomonas putida2010Ingår i: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 12, nr 6, s. 1439-1451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Here the σ-factor requirement for transcription of three similar, but differentially regulated, aer genes of Pseudomonas putida KT2440 is investigated. Previous work has shown that the three Aer proteins, like chemoreceptors, colocalize to a single pole in a CheA-dependent manner. Lack of Aer2 - the most abundant of these three proteins - mediates defects in metabolism-dependent taxis and aerotaxis, while lack of Aer1 or Aer3 has no apparent phenotype. We show, using wild-type and mutant P. putida derivatives combined with P. putida reconstituted FliA- (σ28) and σ70-dependent in vitro transcription assays, that transcription of aer2 is coupled to motility through the flagella σ-factor FliA, while σ70 is responsible for transcription of aer1 and aer3. By comparing activities of the wild-type and mutant forms of the aer2 promoter, we present evidence (i) that transcription from FliA-dependent Paer2 is enhanced by changes towards the Escherichia coli consensus for FliA promoters rather than towards that of P. putida, (ii) that the nature of the AT-rich upstream region is important for both output and σ70 discrimination of this promoter, and (iii) that Paer2 output is directly stimulated by the bacterial alarmone ppGpp and its cofactor DksA.

  • 13287.
    Österberg, Sofia
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Åberg, Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Herrera Seitz, M. Karina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Wolf-Watz, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Shingler, Victoria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Genetic dissection of a motility-associated c-di-GMP signalling protein of Pseudomonas putida2013Ingår i: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 5, nr 4, s. 556-565Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lack of the Pseudomonas putidaPP2258 protein or its overexpression results in defective motility on solid media. The PP2258 protein is tripartite, possessing a PAS domain linked to two domains associated with turnover of c-di-GMP - a cyclic nucleotide that controls the switch between motile and sessile lifestyles. The second messenger c-di-GMP is produced by diguanylate cyclases and degraded by phosphodiesterases containing GGDEF and EAL or HD-GYP domains respectively. It is common for enzymes involved in c-di-GMP signalling to contain two domains with potentially opposing c-di-GMP turnover activities; however, usually one is degenerate and has been adopted to serve regulatory functions. Only a few proteins have previously been found to have dual enzymatic activities - being capable of both synthesizing and hydrolysing c-di-GMP. Here, using truncated and mutant derivatives of PP2258, we show that despite a lack of complete consensus in either the GGDEF or EAL motifs, the two c-di-GMP turnover domains can function independently of each other, and that the diguanylate cyclase activity is regulated by an inhibitory I-site within its GGDEF domain. Thus, motility-associated PP2258 can be added to the short list of bifunctional c-di-GMP signalling proteins.

  • 13288.
    Österholm, Emil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jordbrukets betydelse i stadsnära miljö: En undersökning av Umeå kommuns översiktsplanering för Röbäcksområdet2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study aimed to examine what role and how the agriculture will be affected in a periurban environment as by the comprehensive plan that the municipal has established for the Röbäck area. The study tried to value the importance and role for the agriculture today and in the future. The methods of this study were interviews with farmers, inhabitants and workers of Röbäck, businesses and a sports club based on two types of interviews one survey-based with fixed questions and one in-depth interview with farmers. The municipal comprehensive plan and accompanying environmental impact assessment along relevant literature and the statistical database from Jordbruksverket were used to extract and compile data. The results show that the fields in and surrounding Röbäck contained good agricultural values and the ability to maintain of self-sufficiency in Västerbottens county is low. In the interviews with farmers the fear of not being able to use the farmland as before as a result of complaints on dust, noises, smells and rules on spreading fertilizers and pesticides raised a concern. The interviews showed that people living in Röbäck liked the combination of being close to Umeå city centrum as well as living close to the nature and the open landscapes, but few saw the link between the agriculture in Röbäck and these. The report concludes that the issue is complex and depends on whose interest should go first. There were both positive and negative outcomes of the plan in all the three pillars of sustainability

  • 13289.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    A framework for studying differences between process- and object-oriented discourses2011Ingår i: Proceedings of the 35th Conference of the International Group for the Psychology of Mathematics Education, vol 1: Developing mathematical thinking / [ed] Behiye Ubuz, 2011, s. 367-367Konferensbidrag (Övrigt vetenskapligt)
  • 13290.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Beliefs: A theoretically unnecessary construct?2010Ingår i: Proceedings of the Sixth Congress of the European Society for Research in Mathematics Education. January 28th - February 1st 2009, Lyon, France / [ed] V. Durand-Guerrier, S. Soury-Lavergne & F. Arzarello, Lyon: Institut National de Recherche Pédagogique , 2010, s. 154-163Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper I analyze different existing definitions of the term beliefs, focusing on relations between beliefs and knowledge. Through this analysis I note several problems with different types of definitions. In particular, when defining beliefs through a distinction between belief and knowledge systems, this creates an idealized view of knowledge, seen as something more pure (less affective, less episodic, and more logical). In addition, attention is generally not given to from what point of perspective a definition is made; if the distinction between beliefs and knowledge is seen as being either individual/psychological or social. These two perspectives are also sometimes mixed, which results in a messy construct. Based on the performed analysis, a conceptualization of beliefs is suggested.

  • 13291.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    Characterizing mathematics education research discourse on belief2011Ingår i: Current state of research on mathematical beliefs XVI: Proceedings of the MAVI-16 Conference, June 26-29, 2010, Tallinn, Estonia / [ed] Kirsti Kislenko, Tallinn, Estonia: Institute of Mathematics and Natural Sciences, Tallinn University , 2011, s. 200-217Konferensbidrag (Refereegranskat)
    Abstract [en]

    The discursive use of ‘belief’ in research articles are analyzed as a contribution to the reflexive activity in belief-research, in particular regarding theoretical aspects of the notion of belief. The purpose of this paper is to create an explicitly described procedure for such an analysis, from the selection of data to categorizations of the smallest unit of analysis. The method of analysis builds on some linguistic structures, focusing in this paper on the use of adjectives and verbs in relation to ‘belief’. From the analysis of the use of ‘belief’ in eight articles a set of categories is created describing different uses of the notion of belief.

  • 13292.
    Österholm, Magnus
    Umeå universitet, Fakultet för lärarutbildning, Matematik, teknik och naturvetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    Do students need to learn how to use their mathematics textbooks?: The case of reading comprehension2008Ingår i: Nordisk matematikkdidaktikk, ISSN 1104-2176, Vol. 13, nr 3, s. 53-73Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main question discussed in this paper is whether students need to learn how to read mathematical texts. I describe and analyze the results from different types of studies about mathematical texts; studies about properties of mathematical texts, about the reading of mathematical tasks, and about the reading of mathematical expository texts. These studies show that students seem to develop special reading strategies for mathematical texts that are not desirable. It has not been possible to find clear evidence for the need of a specific ”mathematical reading ability”. However, there is still a need to focus more on reading in mathematics teaching since students seem to develop the non-desirable reading strategies.

  • 13293.
    Österholm, Magnus
    Umeå universitet, Fakultet för lärarutbildning, Matematik, teknik och naturvetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    Kan vi separera läsning från matematikämnet?2009Ingår i: Dyslexi, ISSN 1401-2480, Vol. 14, nr 3, s. 18-21Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    För uppgifter som man använder i undervisning eller prov i matematik så vill man i första hand utveckla eller testa kunskaper i matematik och inte elevernas läsförmåga. Om undervisning i matematik bygger mycket på läsning så verkar det finnas större risk att elever som har svårigheter med läsning också kommer få svårigheter med matematikämnet. En tanke kan därför vara att man vill separera läsning från matematikämnet, för att på så sätt undvika dessa potentiella problem. Mitt syfte med denna artikel är att analysera vissa aspekter av relationer mellan läsning och matematik, för att på detta sätt se om och hur en sådan separering kan göras.

  • 13294.
    Österholm, Magnus
    Umeå universitet, Fakultet för lärarutbildning, Matematik, teknik och naturvetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    Läsförståelsens roll inom matematikutbildning2009Ingår i: Matematikdidaktiska frågor: Resultat från en forskarskola / [ed] Gerd Brandell, Göteborg: Nationellt centrum för matematikutbildning (NCM), Göteborgs universitet , 2009, 1, s. 154-165Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Denna artikel beskriver undersökningar kring hur universitetsstudenter och skolelever läser olika typer av texter. Frågor jag vill besvara är hur man bör förhålla sig till läsning inom matematikutbildning och om man behöver behandla läsförståelse som en del av undervisning inom matematik. I artikeln behandlar jag undersökningar kring läsning av uppgiftstexter samt undersökningar kring läsning av förklarande texter. Därefter jämför jag dessa olika typer av lässituationer och noterar då vissa likheter mellan lässtrategier som elever använder sig av i de olika situationerna. Bland annat noterar jag att texter som innehåller symboler tycks aktivera en speciell lässtrategi hos elever. Denna strategi verkar handla om att fokusera på symboler och andra typer av nyckelord i texten, vilket resulterar i en sämre läsförståelse. En slutsats är därför att det finns behov av att behandla läsning i matematikundervisning eftersom elever på egen hand tenderar att utveckla bristfälliga lässtrategier. Jag diskuterar också förslag på hur man kan göra detta. Som avslutning i artikeln diskuterar jag även hur resultaten om läsning kan ses i relation till andra forskningsresultat.

  • 13295.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Relationships between epistemological beliefs and properties of discourse: Some empirical explorations2010Ingår i: Mathematics and mathematics education: Cultural and social dimensions. Proceedings of MADIF 7 / [ed] C. Bergsten, E. Jablonka & T. Wedege, Linköping: Svensk förening för matematikdidaktisk forskning, SMDF , 2010, s. 241-250Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper I investigate what types of epistemologies are conveyed through properties of mathematical discourse in two lectures. A main purpose is to develop and explore methods for a type of analysis for this investigation. The analysis focuses on the types of statements and types of arguments used in explicit argumentations in the lectures. This type of analysis proves to be useful when characterizing epistemological aspects of lectures. However, some limitations are also noted, in particular that it was common to use more implicit types of argumentations in the lectures, which was not included as data in the present analysis.

  • 13296.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    Students' summaries of mathematical lectures: Comparing the discourse of students with the discourse of lectures2012Ingår i: Mathematics Education: Expanding Horizons. Proceedings of the 35th Annual Conference of the Mathematics Education Research Group of Australasia / [ed] J. Dindyal, L. P. Cheng & S. F. Ng, Singapore: MERGA , 2012, s. 578-585Konferensbidrag (Refereegranskat)
    Abstract [en]

    This study focuses on a distinction between process- and object-oriented discourses when characterising the discourse of university students' summaries of lectures and examining connections between students' discourse and the discourse of lectures. Results show that students' discourse in general tends to be process-oriented, by their use of active verbs and little use of nominalisations. Students' summaries of process-oriented lectures also tend to be more process-oriented, but the differences between individual students are larger than differences caused by variations of the discourse in the lectures.

  • 13297.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    The ontology of beliefs from a cognitive perspective2010Ingår i: Proceedings of the conference MAVI-15: Ongoing research on beliefs in mathematics education, September 8-11, 2009, Genoa, Italy / [ed] F. Furinghetti & F. Morselli, Genoa: Department of Mathematics, University of Genoa , 2010, s. 35-46Konferensbidrag (Refereegranskat)
    Abstract [en]

    In order to refine existing theories of beliefs, attention is given to the ontology of beliefs, in particular how a belief can be seen as a mental object or a mental process. The analysis focuses on some central aspects of beliefs; unconsciousness, context­ualization, and creation and change of beliefs, but also relates to research metho­dology. Through the analysis, the creation of belief is highlighted as a central aspect for more in-depth theories of beliefs. The outline of a theoretical framework is described – a framework that has the benefit of creating a coherent integration of all different aspects discussed, and which can also be used as a framework when designing and analyzing methods for empirical research.

  • 13298.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    The role of mathematical competencies in curriculum documents in different countries2018Ingår i: Perspectives on professional development of mathematics teachers: Proceedings of MADIF 11, The eleventh research seminar of the Swedish Society for Research in Mathematics Education, Karlstad, January 23–24, 2018 / [ed] Johan Häggström, Yvonne Liljekvist, Jonas Bergman Ärlebäck, Maria Fahlgren, Oduor Olande, Karlstad: Svensk förening för MatematikDidaktisk Forskning - SMDF, 2018, s. 131-140Konferensbidrag (Refereegranskat)
    Abstract [en]

    The inclusion of competencies in curriculum documents can be seen as an international reform movement in mathematics education. The purpose of this study is to understand which role mathematical competencies have in curriculum documents in different countries, with a focus on the relationship between competencies and content. Curriculum documents from 11 different countries were analysed. The results reveal three different themes of variation, concerning if the competencies are specific to mathematics, if competencies are described as learning goals, and if such learning goals are differentiated between grade levels.

  • 13299.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    The role of theory when studying epistemological characterizations of mathematics lecture(r)s2012Ingår i: The Montana Mathematics Enthusiast, ISSN 1551-3440, E-ISSN 1551-3440, Vol. 9, nr 3, s. 431-464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study presented in this paper is a contribution to the scientific discussion about the role and use of theory in mathematics education research. In particular, focus is here on the use of and comparison between different types of theories and frameworks, which is discussed primarily through the example of an empirical study examining what types of messages about mathematics are conveyed in lectures. The main purpose of this paper is to examine how different types of theories and frameworks can affect different parts of the research process.

  • 13300.
    Österholm, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå forskningscentrum för matematikdidaktik (UFM).
    The roles of prior knowledge when students interpret mathematical texts2010Ingår i: The first sourcebook on nordic research in mathematics education: Norway, Sweden, Iceland, Denmark and contributions from Finland / [ed] Bharath Sriraman, Christer Bergsten, Simon Goodchild, Gudbjorg Palsdottir, Bettina Dahl Søndergaard & Lenni Haapasalo, Charlotte, NC, USA: Information Age Publishing, 2010, s. 431-440Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In this chapter I examine what roles different types of prior knowledge have in the comprehension process when reading mathematical texts. Through theoretical analyses, three central aspects are highlighted; cognitive structure, cognitive process, and metacognition. For all these three aspects, questions arise regarding relationships between general and content-specific types of prior knowledge. Some empirical studies are described that study these questions.

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