umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
392393394395396397 19701 - 19750 av 19810
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 19701.
    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.

  • 19702.
    Ölund, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Informationslager för stora mängder SNMP-data2012Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    TeliaSoneras driftcentral har ett stort behov av att snabbt samla in statistisk data från noder och kundanslutningar. Insamlat data används sedan för att felsöka och åtgärda olika problem i nätet. För att säkerställa den driftsäkerhet och kvalitet som efterfrågas så behöver ett av systemen vidareutvecklas. Applikationen som utvecklats ska förbättra insamlingen och lagringen av det statistiska datat för att snabba upp analyserna av kvalitet i xDSL-nätet. Kraven på applikationen är att insamlingen, konverteringen samt lagring ska vara horisontellt skalbara. Under utveckling av applikationen har begrepp som multitrådning, meddelandeköer, meddelandemönster, JSON/BSON och NoSQL förekommit. Resultatet av projektet är en prototyp skriven i PHP. Dess funktion är av ett meddelandemönster där en klient läser av en fil som innehåller anslutningsdata, klienten serialiserar datat till JSON och skickar en förfrågan till en jobbserver. Jobbservern tar emot förfrågan och skickar vidare arbetet till första lediga arbetare. Arbetaren tar emot förfrågan och deserialiserar anslutnings-data. Arbetaren ansluter då mot noden, som specificerats i förfrågningen från klienten och hämtar SNMP-datat och gör olika felkontroller innan arbetaren returnerar resultatet till klienten. I slutet av rapporten tas förslag upp till hur prototypen kan vidareutvecklas för att kunna implementeras i produktionsnivå.

  • 19703.
    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!

  • 19704.
    Ölund, Viktor
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mobilapplikation för driftinformation och analysverktyg2014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    TeliaSonera har många delsystem för att analysera kvalitén i TeliaSoneras nät. Några av de huvudsakliga delsystemen är ADSL-analys och Mibview.

    En ADSL-analys visar aktuell status på synk, bredbandshastigheter, bitfel, signal- och brusförhållande, dämpning och omsynkningar på kunder i TeliaSoneras nät.

    Mibview är en mätning som pågår i tre dagar och demonstrerar grafer i olika kategorier, graferna visar data minut för minut under dagarna mätningen sker. Några av de mest tillämpade graferna i analysen är

    IfOperStatus -Visar status på synk

    CurrBrAtuc -Synkhastighet

    Curr24CvAtuc -Inkommande bitfel

     

    TeliaSoneras tekniker har idag ett stort behov av att använda dessa delsystem för att snabbare fatta beslut när tekniker är på plats hos kunden. För tillfället existerar delsystemen i form av teknisk support i datasystem.

    Kravet på projektet är därför att utveckla en applikation som erhåller dessa delsystem till TeliaSoneras tekniker.

     

    Resultatet av projektet är en mobilapp utvecklad i operativsystemet android med delsystemen ADSL-analys och Mibview, där ledning- och hemhjälpstekniker självmant kan tillämpa delsystemen. I mobilappen sker förfrågningar mot script i servrar för att hämta lagrad data från databaser.

    I slutet av rapporten nämns förslag på förbättringar för att appen ska sättas i produktionsnivå.

  • 19705.
    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.

  • 19706.
    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)
  • 19707.
    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.

  • 19708.
    Önnerlöv, Jonathan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Montageplattform: För inredning av två vertikala ventilationsschakt i Garpenbergs gruva2014Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The company Bergteamet, Boliden, Sweden, is installing ventilation shafts of the Garpenberg mine. For such work a platform is needed which you can stand on and work from. The Shaft Reinforcement Team at Bergteamet performs the installation work and is the sponsor of the platform. The project described in this report is performed at the department MEC, Mining Equipment Construction, which has been given the task to design and construct the platform, customized for the current shaft. After this the platform is manufactured and inspected at the workshop at Bergteamet.

    The design work was carried out as follows:

    - After an initial meeting a requirement specification was worked out, describing the problem and previous experiences of platforms and requirements for the design and equipment.

    - A concept sketch was developed with consideration of surrounding factors.

    - A constructed 3D model was presented along with the choice of materials. Improvements were made after feedback from Bergteamet.

    - Development of production drawings. The drawings were reviewed and handed over to the preparer for manufacturing.

     

    The result was a platform designed with different square tubes where the floor follows the geometrical shape of the shaft. The platform is suspended from a rectangular center tube with dimensions 100x100x8, which is centered in the shaft. The purpose of a center tube is that it facilitates the final stage of the work in the shaft, namely the installation of a fall protection. The platform has a roof to protect from stone rain and dripping water. Under the floor is an air tank places to run the air-powered outriggers. Around the workplace there is a guardrail with a door for access and egress. The design work was done using the drawing program SolidWorks. Calculations were made by hand.

    The platform fulfills the requirements defined by the trade organization for mine elevators in Sweden, (BRAGS), as well as Bolidens for the design and Bergteamets internal design requirements. The platform has been manufactured, inspected and soon filled its purpose for the shaft installation in the Garpenberg mine.

  • 19709.
    Önnerlöv, Lisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen Designhögskolan.
    Användarorienterad förarsituation för bergavläsning vid fjärrstyrt skrotningsarbete2013Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Mechanical scaling is one of the most complex operations of all in the mining process. The operators are using both hearing, sight and feel to read the rock and to know where to scale and where to leave. They say they go on gut feeling in great extent, something that comes with experience. The scaling machine is placed into the edge of unsecured and newly blasted rock to hammer off the blocks that has become loose after the blast, but not enough to fall down. It goes without sayingthat it is a risky job. Boliden Mineral has a desire to remotely control this operation from above ground and thus became this challenge a degree project in industrial design. With a focus on ease of use and the sensory feedback, the project aims to develop a proposal on the driver situation that allows the operator to do an as equally good job above as below ground.

  • 19710.
    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.

  • 19711.
    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.

  • 19712.
    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.

  • 19713.
    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.

  • 19714.
    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.

  • 19715.
    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.

  • 19716.
    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)
  • 19717.
    Öquist, Gunnar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Benner, M.
    Why are some nations more successful than others in research impact?: a comparison between Denmark and Sweden2015Ingår i: Incentives and Performance: Governance of Research Organizations / [ed] Isabell M. Welpe, Jutta Wollersheim, Stefanie Ringelhan, Margit Osterloh, Springer, 2015, s. 241-257Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Bibliometric impact analyses show that Swedish research has less international visibility than Danish research. When taking a global view on all subject fields and selecting publications cited higher than the 90th percentile, i.e., the Top 10 %—publications, the Swedish Research Council shows that although Sweden ranks 15 % above world average, Denmark, the Netherlands and Switzerland rank 35–40 % above. To explain these different performances, The Royal Swedish Academy of Sciences asked us to compare the national research systems on three levels: priority setting at national level, governance of universities and direction and funding of research. There are of course many similarities between the Danish and Swedish research systems but there are still subtle differences that have developed over time, which may explain the different international visibility. First of all, it does not depend on different levels of public spending on research and development. However, the core funding of universities relative external funding is higher in Denmark than in Sweden. The academic leadership of Danish universities in terms of board, vice-chancellor, faculty dean and department chair is also more coherent and focused on priority setting, recruitment, organization and deployment of resources to establish research environments that operate at the forefront of international research. On all these points we see a weaker leadership in Sweden. Furthermore, over the last 20 years, public funding of research in Sweden has become more and more unpredictable and program oriented with many new actors, while the Danish funding system, although it also has developed over time, shows more consistency with strong actors to fund individuals with novel ideas. The research policy in Sweden has also developed multiple, sometimes even conflicting goals, which have undermined conditions for high-impact research, while in Denmark a policy to support excellence in research has been more coherent.

  • 19718.
    Öquist, Gunnar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Huner, Norman P.A.
    Department of Plant Sciences, University of Western Ontario, London, Canada.
    Photosynthesis of overwintering evergreen plants2003Ingår i: Annual Review of Plant Physiology and Plant Molecular Biology, ISSN 1040-2519, E-ISSN 2331-0960, Vol. 54, s. 329-355Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    In this review we focus on photosynthetic behavior of overwintering evergreens with an emphasis on both the acclimative responses of photosynthesis to cold and the winter behavior of photosynthesis in conifers. Photosynthetic acclimation is discussed in terms of the requirement for a balance between the energy absorbed through largely temperature-insensitive photochemical processes and the energy used for temperature-sensitive biochemical processes and growth. Cold acclimation transforms the xanthophyll-mediated nonphotochemical antenna quenching of absorbed light from a short-term dynamic response to a long-term sustained quenching for the whole winter period. This acclimative response helps protect the evergreen foliage from photooxidative damage during the winter when photosynthesis is restricted or prevented by low temperatures. Although the molecular mechanisms behind the sustained winter excitation quenching are largely unknown, it does involve major alterations in the organization and composition of the photosystem II antenna. In addition, photosystem I may play an important role in overwintering evergreens not only by quenching absorbed light photochemically via its support of cyclic electron transport at low temperatures, but also by nonphotochemical quenching of absorbed light irrespective of temperature. The possible role of photosystem II reaction centers in nonphotochemical quenching of absorbed energy in overwintering evergreens is also discussed. Processes like chlororespiration and cyclic electron transport may also be important for maintaining the functional integrity of the photosynthetic apparatus of overwintering evergreens both during periods of thawing in winter and during recovery from winter stress in spring. We suggest that the photosynthetic acclimation responses of overwintering evergreens represent specific evolutionary adaptations for plant species that invest in the long-term maintenance of leaf structure in cold climatic zones as exemplified by the boreal forests of the Northern Hemisphere.

  • 19719. Öquist, Mats G.
    et al.
    Erhagen, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Forest Ecology & Management, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Haei, Mahsa
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ilstedt, Ulrik
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Nilsson, Mats B.
    The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition2017Ingår i: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 414, nr 1, s. 113-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background and aims: Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate.

    Methods: We incubated O-horizon soil samples (with either 13C–glucose or 13C–cellulose) from a boreal coniferous forest at 4, 9, 14, and 19 °C, and calculated CUEs based on the amount of 13C–CO2and 13C–labelled microbial biomass produced. The effects of substrate, temperature, and metabolic conditions (representing unlimited substrate supply and substrate limitation) on CUE were evaluated.

    Results: CUE from metabolizing glucose was higher as compared to cellulose. A slight decrease in CUE with increasing temperature was observed in glucose amended samples (but only in the range 9–19 °C), but not in cellulose amended samples. CUE differed significantly with metabolic conditions, i.e. CUE was higher during unlimited growth conditions as compared to conditions with substrate limitation.

    Conclusions: We conclude that it is integral to account for both differences in CUE during different metabolic phases, as well as complexity of substrate, when interpreting temperature dependence on CUE in incubation studies.

  • 19720. Öquist, Mats
    et al.
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Klemedtsson, Leif
    Harrysson Drotz, Stina
    Grip, Harald
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Nilsson, Mats
    Water availability controls microbial temperature responses in frozen soil CO2 production2009Ingår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 15, nr 11, s. 2715-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Soil processes in high-latitude regions during winter are important contributors to global carbon circulation, but our understanding of the mechanisms controlling these processes is poor and observed temperature response coefficients of CO2 production in frozen soils deviate markedly from thermodynamically predicted responses (sometimes by several orders of magnitude). We investigated the temperature response of CO2 production in 23 unfrozen and frozen surface soil samples from various types of boreal forests and peatland ecosystems and also measured changes in water content in them after freezing. We demonstrate that deviations in temperature responses at subzero temperatures primarily emanates from water deficiency caused by freezing of the soil water, and that the amount of unfrozen water is mainly determined by the quality of the soil organic matter, which is linked to the vegetation cover. Factoring out the contribution of water limitation to the CO2 temperature responses yields response coefficients that agree well with expectations based on thermodynamic theory concerning biochemical temperature responses. This partitioning between a pure temperature response and the effect of water availability on the response of soil CO2 production at low temperatures is crucial for a thorough understanding of low-temperature soil processes and for accurate predictions of C-balances in northern terrestrial ecosystems.

  • 19721. Öquist, M.G.
    et al.
    Laudon, Hjalmar
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Winter soil frost conditions in boreal forests control growing season soil CO2 concentration and its atmospheric exchange2008Ingår i: Global Change Biology, Vol. 14, nr 12, s. 2839-2847Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact of changes in winter soil frost regime on soil CO2 concentration and its atmospheric exchange in a boreal Norway spruce forest was investigated using a field-scale soil frost manipulation experiment. The experiment comprised three treatments: deep soil frost, shallow soil frost and control plots (n = 3). Winter soil temperatures and soil frost distribution were significantly altered by the different treatments. The average soil CO2 concentrations during the growing season were significantly lower in plots with deep soil frost than in plots with shallow soil frost. The average CO2 soil-atmosphere exchange rate exhibited the same pattern, and differences in soil respiration rates among the treatments were statistically significant. Both the variation in soil CO2 concentration and the CO2 soil-atmosphere exchange rate could statistically be explained by the differences in the maximum soil frost depth during the previous winter. A response model for growing season soil respiration rates suggests that every 1 cm change in winter soil frost depth will change the emission rates by ca. 0.01 g CO2 m(-2) day(-1), corresponding to 0.2-0.5% of the estimated net ecosystem productivity (NEP). This suggests that the soil frost regime has a significant influence on the C balance of the system, because interannual variations in soil frost up to 60 cm have been recorded at the site. We conclude that winter climate conditions can be important in controlling C balances in northern terrestrial ecosystems, and also that indirect effects of the winter season must be taken into account, because these can affect the prevailing conditions during the growing season.

  • 19722.
    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)
  • 19723.
    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.

  • 19724.
    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.

  • 19725.
    Örestig, Johan
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Pedagogiska institutionen.
    Bäckström, Hanna
    Umeå universitet, Samhällsvetenskapliga fakulteten, Umeå centrum för genusstudier (UCGS).
    Persson, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Arkitekthögskolan vid Umeå universitet.
    EU-migrantdebatten som ideologi2015Ingår i: Fronesis, ISSN 1404-2614, nr 52-53, s. 240-252Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 19726.
    Örjansen, Beate
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Kan probiotika forebygge utviklingen av eller behandle atopisk eksem hos barn?2012Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 19727.
    Örnberg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Fartygsanslutningar till landströmsnätet I Umeå hamn2015Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Fartygstransport drivs av marina bränslen som avger avgasutsläpp. När fartygen står i hamn förbränner de sitt eget bränsle för elgenerering ombord, förbränningen orsakarluftföroreningar och buller i hamnområdet. Genom de luftföroreningar som sker från koldioxid, koloxid, svaveloxid, kväveoxid och partiklar fås negativa effekter på människa, miljö och ger samhället höga kostnader. För att minska utsläppen kan man ansluta fartygen till elnät på land. Syftet med arbetet var att undersöka elnätets potential till fartygsanslutningar i hela Umeå Hamn. Bakgrunden var att Kvarken Ports (ägare av Umeå Hamn och färjan) planerar en ny färja som skall sjösättas år 2020 och trafikera sjöleden mellan Umeå och Vasa. De vill utreda möjligheterna att landansluta fartyget till elnätet och elnätsägaren Umeå energi måste undersöka förutsättningarna.Arbetet är utfört med bakgrund av totalt sex fartyg fördelade på tre hamnplatser, färjeterminalen, inre hamnen och Gustavs udde med ett effektkrav på totalt 3,755 MVA. Vid dimensionering undersöktes två lösningar för inkoppling av landström, den ena genom inkoppling på genomgående vindkraftkabel och andra vid närmaste uttagspunkt för befintligt nät.För att undersöka landströmmens fördelar undersöktes miljöpåverkan och kostnadsvinster. Vindkraften som produceras vid Umeå hamn består av tre verk som under år 2014 producerade 13,9 GWh medan den beräknade energiåtgången för fartygen är beräknat till 3,95 GWh/år. Producerande enhet i form av vindkraft är inte kontinuerligt och andra energikällor behövs. Kablarna som går genom Umeå hamn är inkopplade till Holmsunds fördelningsstation som kan försörja fartygsanslutningarna vid låg vindkraftsproduktion. Arbetet visade på starkt elnät oberoende val av lösning. Fartygsanslutningar i hamnen krävde utbyggnad av elnätet med en investering mellan 800 tkr upp till 1,7 Mkr beroende på val av lösning. Vid inkoppling till landström blir elpriset för fartygen billigare eftersom de kan köpa landel till lägre pris än kostnaden för dem att själva producera ombord. Utsläppen vid inkoppling av landström reduceras till över 98 % jämfört med bränslegenererad el. Utsläppsminskningenger ekonomisk besparingen genom lägre samhällskostnader till följd av en bättre hälsa för människa, miljö och natur. Det här bevisar att landström kan bidra till att starkt reducera utsläppen i områden runt hamnen och minska kostnader.

  • 19728.
    Örnberg, Lina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Effektivisering av byggservice, PEAB2013Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Alla företag i dagens samhälle strävar efter att utveckla sin verksamhet för att hela tiden hålla jämna steg med konkurrenterna. Siktar företaget på att vara bland de främsta i branschen måste de inte bara hålla jämna steg med de andra, utan även leda utvecklingen. Det här arbetet har gått ut på att med enkla medel öka Peab byggservice möjligheter att vara bland de främsta. Fokus har legat på att ta fram underlag som kan förenkla dels dokumenteringen av material, maskiner och arbetade timmar, men också hanteringen av släpvagnar. Det har även tagits fram tekniska hjälpmedel samt att förrådsområdet inom byggservice har organiserats. Vissa delar fungerar i dagsläget relativt bra medan andra inte gör det. För att nå bättre resultat inom en verksamhet så gäller det att både effektivisera det som fungerar bra och dåligt. I och med effektiviseringen framställdes nya underlag så som mallar, formulär och överenskommelser, detta för att förenkla arbetet för arbetsledarna när det gäller slutsummering och sammanställning av projekt. Utöver det så togs även tekniska hjälpmedel, i form av appar, fram för att kunna digitalisera en stor del av den projektinformation som arbetsledarna behöver ha tillgång till. Detta visade sig ge mycket positiva effekter i arbetsledarnas vardag, med bättre tillgång till information och större flexibilitet i arbetet. Dessutom förbättrades förutsättningarna för att kunna köpa in och lagra material i egna lokaler då en APD-plan upprättades över byggservice tillhörande förrådsområde. Genom att köpa in större partier medmaterial så kan kostnader och resor hållas nere, vilket ger en effektivare användning av resurser och tillgångar. Dessa hjälpmedel kommer att ligga som grund till ett effektivare och mer framåtsträvande arbetssätt inom byggservice.

  • 19729.
    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)
  • 19730. Örtenblad, Marcus
    et al.
    Parola, Stephane Chaput, Frédéric Desroches, Cédric Sigala, Catherine Létoffé, Jean Marie Miele, Philippe Baldeck, Patrice L. Eliasson, Bertil Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.Eriksson, Anders Lopes, Cesar
      Hybrid Materials for Optical Limiting        2005Proceedings (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    Optical limiting materials based on alkynyl platinum derivatives and thiacalixarenes were produced using the sol-gel process. The molecular species were grafted to the matrix (class II hybrid) in order to maximise the concentration and the stability of the material. Broadband optical limiting performances in the visible wavelength region was observed in the prepared materials. Thermomechanical characterisation of the matrix will also be discussed.

  • 19731.
    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)
  • 19732.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Architectures, design methodologies, and service composition techniques for Grid job and resource management2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The field of Grid computing has in recent years emerged and been established as an enabling technology for a range of computational eScience applications. The use of Grid technology allows researchers and industry experts to address problems too large to efficiently study using conventional computing technology, and enables new applications and collaboration models. Grid computing has today not only introduced new technologies, but also influenced new ways to utilize existing technologies.This work addresses technical aspects of the current methodology of Grid com- puting; to leverage highly functional, interconnected, and potentially under-utilized high-end systems to create virtual systems capable of processing problems too large to address using individual (supercomputing) systems. In particular, this thesis studies the job and resource management problem inherent to Grid environments, and aims to contribute to development of more mature job and resource management systems and software development processes. A number of aspects related to Grid job and resource management are here addressed, including software architectures for Grid job management, design methodologies for Grid software development, service composition (and refactorization) techniques for Service-Oriented Grid Architectures, Grid infrastructure and application integration issues, and middleware-independent and transparent techniques to leverage Grid resource capabilities.The software development model used in this work has been derived from the notion of an ecosystem of Grid components. In this model, a virtual ecosystem is defined by the set of available Grid infrastructure and application components, and ecosystem niches are defined by areas of component functionality. In the Grid ecosys- tem, applications are constructed through selection and composition of components, and individual components subject to evolution through meritocratic natural selection. Central to the idea of the Grid ecosystem is that mechanisms that promote traits beneficial to survival in the ecosystem, e.g., scalability, integrability, robustness, also influence Grid application and infrastructure adaptability and longevity. As Grid computing has evolved into a highly interdisciplinary field, current Grid applications are very diverse and utilize computational methodologies from a number of fields. Due to this, and the scale of the problems studied, Grid applications typically place great performance requirements on Grid infrastructures, making Grid infrastructure design and integration challenging tasks. In this work, a model of building on, and abstracting, Grid middlewares has been developed and is outlined in the papers. In addition to the contributions of this thesis, a number of software artefacts, e.g., the Grid Job Management Framework (GJMF), have resulted from this work.

  • 19733.
    Östberg, Per-Olov
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Virtual infrastructures for computational science: software and architectures for distributed job and resource management2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Inom beräkningsvetenskap begränsar ofta mängden tillgänglig beräkningskraft både storlek på problem som kan ansättas såväl som kvalitet på lösningar som kan uppnås. Metodik för skalning av beräkningskapacitet till stor skala (dvs större än kapaciteten hos enskilda resurscentras) baseras för närvarande på aggregering och federation av distribuerade beräkningsresurser. Oavsett hur denna resursaggregering tar sig uttryck tenderar skalning av vetenskapliga beräkningar till storskalig nivå att inkludera omformulering av problemställningar och beräkningsstrukturer för att bättre utnyttja problem- och resursparallellism. Effektiv parallellisering och skalning av vetenskapliga beräkningar är svårt och kompliceras ytterligare av faktorer som medföljer resursaggregering, t.ex. heterogeneitet i resursmiljöer och beroenden i programmeringsmodeller och beräkningsmetoder. Detta utbytesförhållande illustrerar komplexiteten i utförande av beräkningar och behovet av mekanismer som erbjuder högre abstraktionsnivåer för hantering av beräkningar i distribuerade beräkningsmiljöer.Denna avhandling diskuterar design och konstruktion av virtuella beräkningsinfrastrukturer som abstraherar komplexitet i utförande av beräkningar, frikopplar design av beräkningar från utförande av beräkningar samt underlättar storskalig användning av beräkningsresurser för vetenskapliga beräkningar. I synnerhet behandlas jobb- och resurshantering i distribuerade virtuella vetenskapliga infrastrukturer avsedda för Grid och Cloud computing miljöer. Det huvudsakliga området för avhandlingen är Grid computing, vilket adresseras med service-orienterad beräknings- och arkitekturmetodik. Arbetet diskuterar metodik och mekanismer för konstruktion av virtuella beräkningsinfrastrukturer samt gör bidrag inom enskilda områden som jobbhantering, applikationsintegrering, jobbprioritering och service-baserad programvaruutveckling.Utöver vetenskapliga publikationer bidrar detta arbete också med bidrag i form av programvarusystem som illustrerar de metoder som diskuteras. The Grid Job Management Framework (GJMF) abstraherar komplexitet i hantering av beräkningsjobb och erbjuder en uppsättning middleware-agnostiska gränssnitt för körning, kontroll och övervakning av beräkningsjobb i distribuerade beräkningsmiljöer. FSGrid erbjuder en generisk modell för specifikation och delegering av resurstilldelning i virtuella organisationer och grundar sig på distribuerad rättvisebaserad jobbprioritering. Mekanismer som dessa frikopplar jobb- och resurshantering från fysiska infrastruktursystem samt underlättar konstruktion av skalbara virtuella infrastrukturer för beräkningsvetenskap.

  • 19734.
    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)
  • 19735.
    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.

  • 19736.
    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)
  • 19737.
    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.

  • 19738.
    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.

  • 19739.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Impact of service overhead on service-oriented Grid architectures2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Grid computing applications and infrastructures build heavily on Service-Oriented Computing development methodology and are often realized as Service-Oriented Ar- chitectures. Current Service-Oriented Architecture methodology renders service components as Web Services, and suffers per- formance limitations from Web Service overhead. The Grid Job Management Framework (GJMF) is a flexible Grid in- frastructure and application support component realized as a loosely coupled network of Web Services that offers a range of abstractive and platform independent interfaces for middleware- agnostic Grid job submission, monitoring, and control. In this paper we a present a performance evaluation aimed to characterize the impact of service overhead on Grid Service- Oriented Architectures and evaluate the efficiency of the GJMF architecture and optimization mechanisms designed to mediate impact of Web Service overhead on architecture performance.

  • 19740.
    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.

  • 19741.
    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.

  • 19742.
    Östberg, Per-Olov
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Elmroth, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Service development abstraction: A design methodology and development toolset for abstractive and flexible service-based software2011Ingår i: Cloud Computing and Service Science / [ed] Ivanov, van Sinderen, and Shishkov, Springer, 2011Kapitel i bok, del av antologi (Refereegranskat)
  • 19743.
    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.

  • 19744.
    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.

  • 19745.
    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.

  • 19746.
    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.

  • 19747.
    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.

  • 19748.
    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.

  • 19749.
    Östberg, Yngve
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet).
    Pinne, Marija
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Benz, Roland
    Rosa, Patricia
    Bergström, Sven
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Elimination of channel-forming activity by insertional inactivation of the p13 gene in Borrelia burgdorferi2002Ingår i: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 184, nr 24, s. 6811-6819Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    P13 is a chromosomally encoded 13-kDa integral outer membrane protein of the Lyme disease agent, Borrelia burgdorferi. The aim of this study was to investigate the function of the P13 protein. Here, we inactivated the p13 gene by targeted mutagenesis and investigated the porin activities of outer membrane proteins by using lipid bilayer experiments. Channel-forming activity was lost in the p13 mutant compared to wild-type B. burgdorferi, indicating that P13 may function as a porin. We purified native P13 to homogeneity by fast performance liquid chromatography and demonstrated that pure P13 has channel-forming activity with a single-channel conductance in 1 M KCl of 3.5 nS, the same as the porin activity that was lost in the p13 mutant. Further characterization of the channel formed by P13 suggested that it is cation selective and voltage independent. In addition, no major physiological effects of the inactivated p13 gene could be detected under normal growth conditions. The inactivation of p13 is the first reported inactivation of a gene encoding an integral outer membrane protein in B. burgdorferi. Here, we describe both genetic and biophysical experiments indicating that P13 in B. burgdorferi is an outer membrane protein with porin activity.

  • 19750.
    Österberg, Sofia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    How can pharmacists contribute to a more effective care of patients with hypertension or diabetes?: How can pharmacists contribute to a more effective care of patients with hypertension or diabetes?2015Självständigt arbete på grundnivå (yrkesexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
392393394395396397 19701 - 19750 av 19810
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf