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  • 101.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Salmi, Tapio
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo, Finland.
    Reaction Network upon One-pot Catalytic Conversion of Pulp2013In: / [ed] Sauro Pierucci, Jiří J. Klemeš, AIDIC - associazione italiana di ingegneria chimica, 2013, Vol. 32, p. 649-654Conference paper (Refereed)
    Abstract [en]

    Nordic sulphite and sulphate (Kraft) cellulose originating from Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin Amberlyst 70 for which the optimal reaction conditions leading to best yields were determined. For this system, maximum yields of 53 mol-% and 57 mol-% were obtained for formic and levulinic acid, respectively. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The prototype model was able to describe the behaviour of the system in a satisfactory manner.

  • 102.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samikannu, Ajaikumar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Catalytic conversion of lignocellulosic materials2010Conference paper (Other academic)
  • 103.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Åbo Akademi.
    Salmi, Tapio
    Åbo Akademi.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Experimental and Kinetic Modelling Studies upon Conversion of Nordic Pulp into Levulinic AcidManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, sulphite cellulose from a Swedish pulp mill was applied as the raw material upon catalytic, one-pot synthesis of green platform chemicals – levulinic and formic acids. Cationic ion-exchange resin, Amberlyst 70, was the catalyst of choice and the optimal reaction conditions leading to best yields were determined. The kinetic experiments were performed in a temperature range of 180–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. For this system, maximum theoretical yields of around 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt %. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here, the concept introduces a one-pot procedure providing a route to green platform chemicals from coniferous soft wood pulp to produce levulinic and formic acids, respectively.

  • 104.
    Ahlkvist, Johan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wärnå, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Salmi, Tapio
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University,Turku, Finland.
    Heterogeneously catalyzed conversion of nordic pulp to levulinic and formic acids2016In: Reaction Kinetics, Mechanisms and Catalysis, ISSN 1878-5190, E-ISSN 1878-5204, Vol. 119, no 2, p. 415-427Article in journal (Refereed)
    Abstract [en]

    Herein, one-pot conversion of cellulose to platform chemicals, formic and levulinic acids was demonstrated. The catalyst selected was an affordable, acidic ion-exchange resin, Amberlyst 70, whereas the cellulose used was sulfite cellulose delivered by a Swedish pulp mill. Furthermore, in an attempt to better understand the complex hydrolysis network of the polysaccharide, kinetic experiments were carried out to pinpoint the optimal reaction conditions with an initial substrate concentration of 0.7–6.0 wt% and a temperature range of 180–200 °C. Higher temperatures could not be used due to the limitations in the thermal stability of the catalyst. Overall, maximum theoretical yields of 59 and 68 mol% were obtained for formic and levulinic acid, respectively. The parameters allowing for the best performance were reaction temperature of 180 °C and initial cellulose concentration of 0.7 wt%. After studying the behavior of the system, a simplified reaction network in line with a mechanistic approach was developed and found to follow first order reaction kinetics. A satisfactory fit of the model to the experimental data was achieved (97.8 % degree of explanation). The catalyst chosen exhibited good mechanical strength under the experimental conditions and thus, a route providing green platform chemicals from soft wood pulp from coniferous trees (mixture of Scots Pine and Norway Spruce) was demonstrated.

  • 105.
    Ahlm, Kristoffer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Prey specialization and diet of frogs in Borneo2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Earlier studies of the diet of frogs indicate that most adult frogs are mainly insectivorous. Overall, frogs are viewed more as generalists than specialists in terms of their diet. However, despite earlier studies, there are still gaps in our knowledge regarding what frogs tend to eat and the degree of specialization. The aim of this study was to investigate the diet choice of frogs in a tropical ecosystem. The present study was conducted in a well-known hotspot for frogs with 66 of the 156 known frog species in Borneo found in a protected area comprising of primary rainforest.

     

    Frogs were caught in the field and their stomachs were flushed. The stomach content was retrieved, sorted to prey categories, and the diet analysed. In addition, the frogs were identified to species level. The frogs belonged to five families: Bufonidae, Dicroglossidae, Megophryidae, Microhylidae and Ranidae. My results show that the most common food source was ants, which constituted 63.7 % of the total food for all studied frog families. Termites, beetles and spiders made up 11.7 %, 4.2 % and 2.8 % of the total prey, respectively. The results from the analysis of Shannon’s diversity index supported two diet specialist families, the Bufonidae and Megophridae, which had a significantly lower mean diversity index compared to the generalist Dicroglossidae. To better reveal differences in frog’s diet in this ecosystem, further studies using larger sample size are needed.

     

     

     

  • 106.
    Ahlstrand, Samuel
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Partiformning vid intern materialförsörjning och layoutanpassning av lager: En fallstudie vid GE Healthcare Umeå av två-binge, supermarkets ochmaterialspindlar2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    GE Healthcare (GEHC) Umeå har vid sin implementering av Lean genomfört förändringar i lagerstrukturen som är i behov av bättre anpassning. GEHC Umeås nya lagerstruktur innebär öppna supermarkets med förändrade försörjningsrutiner från lager till produktion. Ett två-binge system har implementeras där signalbehållare med material fylls av lageransvariga materialspindlar.

    Det första identifierade problemet och forskningsfrågan utgör två-bingarnas kvantiteter som bestämmer mängden artiklar vid monteringsstationerna. Dessa behöver ses över och en rutin för bestämmande av kvantitet behöver etableras. Som den andra, och oberoende forskningsfrågan, har antalet supermarkets (lager) och dessmaterialspindlar identifieras som är många till antalet och utspridda med begränsad samordning.

    Ett tidigare examensarbete, litteraturstudier, intervjuer samt egna observationer på plats har används för att beskriva nuläget genom både kvalitativa och kvantitativa metoder. På grund av bristen på liknande problem i litteraturen har externa partiformningsmetoder och lagerstyrning används och komplimenterats med simulering för två-binge systemet som del i besvarandet av den första frågeställningen. För den andra frågeställningen har delar ur förenklad systematisk lokalplanläggning används där bland annat olika centraliseringsgrader undersökts med simulering av materialtransporter vid olika artikelplaceringar.

    Idag sätts kvantiteten efter prognoserat användande utifrån personliga erfarenheter. Samordningen mellan materialspindlarna är bristande och nyttjandegraden upplevs ojämn samtidigt som godsmottagningen skulle gynnas av ökad kapacitet. Standardiserade processer i materialhanteringen saknas och produktionsgrupperna har skilda arbetssätt som antaskunna gynnas av en centralisering där gemensamma rutiner lättare kan etableras.

    De historiska transaktionerna visar att det finns utrymme för förbättringar då vissa artiklar genererar långa transportsträckor på grund lagerplats i förhållande till var de används iproduktionen. De nya binge-kvantiteterna från partiformningsmetoderna EOQ, m-EOQ och Kanbanformeln har testats i simulering av påfyllning och materialåtgång via en implementation i Excel VBA.

    Kanbanformeln uppvisar högsta servicenivån 90 %, för lägsta totalkostnaden och minskad kapitalbindning. Kanbankvantiteterna minskar den totala kostnaden med 20 %. Antalet påfyllningar skulle öka med 7 % och antalet artiklar i produktion minskar med 59%. För layoutanpassningen har även simulering av olika orderplock och artikelplaceringen genomförts. Resultatet visar att en centraliseringsgrad är möjlig med en liten ökning avmaterialtransporterna. Det framgår även att artiklar som plockas väldigt sällan är beräknade att ta upp 89 hyllställage av totalt 230 stycken och bör ses över. Detta tillsammans med kravspecifikationen från analys-delen har hjälpt för att generera olika koncept.

    GEHC Umeå bör använda Kanbanformeln i framtiden för bestämmande av kvantiteten i bingarna. Vissa anpassningar för gemensamma artiklar i Comm-lagret och artiklar utan historiska efterfrågan bör ske. För layouten bör GEHC Umeå först och främst flytta artiklarsom idag bidrar med onödiga transporter. På längre sikt bör en ökad grad centralisering avlagren vara möjlig med hänsyn till fördelar vid samordning och informell spridning av arbetsrutiner. Materialspindlarna bör underlätta för godsmottagningen, delta i bristrapportering samt förbättringsarbetet. Utöver detta bör möjligheter till ökat samarbetet mellan materialplaneringen, produktionsplaneringen och materialspindlarna undersökas

  • 107. Ahlstrand, Tuuli
    et al.
    Tuominen, Heidi
    Beklen, Arzu
    Torittu, Annamari
    Oscarsson, Jan
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sormunen, Raija
    Pöllänen, Marja T.
    Permi, Perttu
    Ihalin, Riikka
    A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-82017In: Virulence, ISSN 2150-5594, E-ISSN 2150-5608, Vol. 8, no 2, p. 115-134Article in journal (Refereed)
    Abstract [en]

    Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI− mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations.

  • 108.
    Ahmad, Farooq
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Lindgren, Helena
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Selection of foundational ontology for collaborative knowledge modeling in healthcare domain2010In: Artificial intelligence: methodology, systems, and applications / [ed] Dicheva, Darina; Dochev, Danail, Springer Berlin/Heidelberg, 2010, p. 261-262Conference paper (Refereed)
    Abstract [en]

    Ontology design is an important process for structuring knowledge to be reused in different projects in the health domain. In this paper, we describe an ontology design for the collaborative knowledge building system ACKTUS to be used for developing personalized knowledge applications for different domains. Different foundational ontologies were compared with respect to selected criteria considered vital for the project, such as modularity and descriptiveness.

  • 109.
    Ahmad, Irfan
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
    Rouf, Syed Fazle
    Sun, Lei
    Cimdins, Annika
    Shafeeq, Sulman
    Le Guyon, Soazig
    Schottkowski, Marco
    Rhen, Mikael
    Romling, Ute
    BcsZ inhibits biofilm phenotypes and promotes virulence by blocking cellulose production in Salmonella enterica serovar Typhimurium2016In: Microbial Cell Factories, ISSN 1475-2859, E-ISSN 1475-2859, Vol. 15, article id 177Article in journal (Refereed)
    Abstract [en]

    Background: Cellulose, a 1,4 beta-glucan polysaccharide, is produced by a variety of organisms including bacteria. Although the production of cellulose has a high biological, ecological and economical impact, regulatory mechanisms of cellulose biosynthesis are mostly unknown. Family eight cellulases are regularly associated with cellulose biosynthesis operons in bacteria; however, their function is poorly characterized. In this study, we analysed the role of the cellulase BcsZ encoded by the bcsABZC cellulose biosynthesis operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) in biofilm related behavior. We also investigated the involvement of BcsZ in pathogenesis of S. Typhimurium including a murine typhoid fever infection model. Result: In S. Typhimurium, cellulase BcsZ with a putative periplasmic location negatively regulates cellulose biosynthesis. Moreover, as assessed with a non-polar mutant, BcsZ affects cellulose-associated phenotypes such as the rdar biofilm morphotype, cell clumping, biofilm formation, pellicle formation and flagella-dependent motility. Strikingly, although upregulation of cellulose biosynthesis was not observed on agar plate medium at 37 degrees C, BcsZ is required for efficient pathogen-host interaction. Key virulence phenotypes of S. Typhimurium such as invasion of epithelial cells and proliferation in macrophages were positively regulated by BcsZ. Further on, a bcsZ mutant was outcompeted by the wild type in organ colonization in the murine typhoid fever infection model. Selected phenotypes were relieved upon deletion of the cellulose synthase BcsA and/or the central biofilm activator CsgD. Conclusion: Although the protein scaffold has an additional physiological role, our findings indicate that the catalytic activity of BcsZ effectively downregulates CsgD activated cellulose biosynthesis. Repression of cellulose production by BcsZ subsequently enables Salmonella to efficiently colonize the host.

  • 110. Ahmad, S.
    et al.
    Zhao, W.
    Renström, F.
    Rasheed, A.
    Zaidi, M.
    Samuel, M.
    Shah, N.
    Mallick, N. H.
    Shungin, Dmitry
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Umeå University, Faculty of Medicine, Department of Odontology.
    Zaman, K. S.
    Ishaq, M.
    Rasheed, S. Z.
    Memon, F-ur-R
    Hanif, B.
    Lakhani, M. S.
    Ahmed, F.
    Kazmi, S. U.
    Deloukas, P.
    Frossard, P.
    Franks, P. W.
    Saleheen, D.
    A novel interaction between theFLJ33534locus and smokingin obesity: a genome-wide study of 14 131 Pakistani adults2016In: International Journal of Obesity, ISSN 0307-0565, E-ISSN 1476-5497, Vol. 40, no 1, p. 186-190Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Obesity is a complex disease caused by the interplay of genetic and lifestyle factors, but identification of gene-lifestyle interactions in obesity has remained challenging. Few large-scale studies have reported use of genome-wide approaches to investigate gene-lifestyle interactions in obesity. METHODS: In the Pakistan Risk of Myocardial Infraction Study, a cross-sectional study based in Pakistan, we calculated body mass index (BMI) variance estimates (square of the residual of inverse-normal transformed BMI z-score) in 14 131 participants and conducted genome-wide heterogeneity of variance analyses (GWHVA) for this outcome. All analyses were adjusted for age, age(2), sex and genetic ancestry. RESULTS: The GWHVA analyses identified an intronic variant, rs140133294, in the FLJ33544 gene in association with BMI variance (P-value = 3.1 x 10(-8)). In explicit tests of gene x lifestyle interaction, smoking was found to significantly modify the effect of rs140133294 on BMI (Pinteraction = 0.0005), whereby the minor allele (T) was associated with lower BMI in current smokers, while positively associated with BMI in never smokers. Analyses of ENCODE data at the FLJ33534 locus revealed features indicative of open chromatin and high confidence DNA-binding motifs for several transcription factors, providing suggestive biological support for a mechanism of interaction. CONCLUSIONS: In summary, we have identified a novel interaction between smoking and variation at the FLJ33534 locus in relation to BMI in people from Pakistan.

  • 111.
    Ahmed, Shibbir
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Cadmium sulphide / Zinc sulphide quantum dot decoration of three-dimensional porous graphene2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 112. Ahn, Ji Hoon
    et al.
    Schmid, Markus
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Editorial overview: Growth and development: Change is in the air: how plants modulate development in response to the environment2017In: Current opinion in plant biology, ISSN 1369-5266, E-ISSN 1879-0356, Vol. 35, p. IV-VIArticle in journal (Refereed)
  • 113.
    Ahonen, Jani
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Can morphologic restoration of hydropower outlet channels create hydraulically suitable spawning and larvae habitats for grayling?: Modelling the effects of environmental measures with HEC-RAS.2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to model if hydraulically suitable habitats for juvenile and spawning grayling could be created by morphological restoration alone in the Bjurfors Övre hydropower outlet channel in the Ume River Basin. The study was done by 2D modelling with HEC-RAS using hourly water flow and level data collected during the period 20160521-20161029. Suitable water depth and velocity values for larvae and spawning grayling were collected from literature. Environmental measures for the Bjurfors Övre outlet channel were designed based on the morphology in outlet channels with documented reproducing grayling populations and large habitat diversities. The outlet channel at present morphology and after morphological modifications were modelled at different flow scenarios (0-369m3/s) and areas of suitable water velocities and depths before and after proposed measures were compared. Results show that suitable velocity areas would increase with a factor of between 1,03-1,81 and the suitable depth areas with a factor of 2,34-19,09 and that suitable depths may be the major limiting factor in current conditions. Results also show that zero-flow events at Bjurfors Övre hydropower plant create unsuitable velocities for larvae and spawning grayling and that the frequency and duration of such events could be more limiting than the mere occurrence of such events. The study indicates that the morphological restoration in hydropeaking outlet channels could improve the availability of habitats with suitability water depth and velocity not only for larvae and spawning grayling, but for other lotic organisms. The study also showed that HEC-RAS modelling is a potential resource effective way to assess to what extent certain proposed environmental measures may create suitable water depths and velocities in hydropeaking outlet channels.

  • 114.
    Ahonen, Jani
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Korttidsregleringsmönster i Ångermanälvens avrinningsområde: Har elmarknadens avreglering påverkat regleringsintensiteten?2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The effects of the deregulation of the electricity market 1996 in Sweden on short-term hydropower regulation are unknown. This report investigates patterns in subdaily regulation in the Ångerman River Basin during the period 1993-2011. Differences in subdaily flows and zero flow events between the periods 1993-1995 and 1996-2011 were studied by analyzing hourly data from 8 regulated and 8 unregulated locations with four subdaily flow variation indices. No correlations between the market deregulation and the regulation intensity in the Ångerman River basin were detected. The number of days natural ranges of variability were exceeded and the magnitude of subdaily variation were significantly higher at regulated locations. Zero flow events increased substantially when the periods 1993-2007 and 2008-2011 were compared. Significant correlations were detected in the summer periods between dry years and high magnitudes for the indices that measured variation in volume and low magnitudes for subdaily flow reversals. Zero flow events in the summer periods increased during dry years if the period 2008-2011 were excluded. The major conclusions are that the deregulation of the electricity market has not affected the subdaily regulation of the Ångerman River and that the regulated sites show highly unnatural subdaily variations. Regulation intensity and zero flows events increases during summertime in dry years and the latter also increased substantially after 2007. The current regulation regime is considered harmful for riverine ecosystems and the high and increasing levels of subdaily flow alteration shows the urgent need of national directives for subdaily hydropower operation.

  • 115. Aichroth, Patrick
    et al.
    Weigel, Christian
    Kurz, Thomas
    Stadler, Horst
    Drewes, Frank
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Björklund, Johanna
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Schlegel, Kai
    Berndl, Emanuel
    Perez, Antonio
    Bowyer, Alex
    Volpini, Andrea
    MICO - MEDIA IN CONTEXT2015In: 2015 IEEE International Conference on Multimedia & Expo Workshops (ICMEW), 2015Conference paper (Refereed)
    Abstract [en]

    The abundance of digital content requires cost-effective technologies to extract the hidden meaning from media objects. However, current approaches fail to deal with the challenges related to cross-media analysis, metadata publishing, querying and recommendation that are necessary to overcome this challenge. In this paper, we describe the EU project MICO (Media in Context) which aims to provide the necessary technologies based on open-source software (OSS) core components.

  • 116. Aid, T.
    et al.
    Hyvarinen, S.
    Vaher, M.
    Koel, M.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Saccharification of lignocellulosic biomasses via ionic liquid pretreatment2016In: Industrial crops and products (Print), ISSN 0926-6690, E-ISSN 1872-633X, Vol. 92, p. 336-341Article in journal (Refereed)
    Abstract [en]

    The current work focuses on the pretreatment efficiency of ILs combined with heat for woody biomass consisting of spruce, birch and pine as well as winter wheat straw. The latter was investigated as a comparison and with the aim to enhance its digestibility during enzymatic hydrolysis whereby the influence of IL-treatment to cellulose resistance for hydrolysis was investigated. Considering the wood species, the most common and industrially important wood species in Northern Europe were chosen in the present work and the goal was to obtain fermentable sugars and their degradation product, i.e. 5-hydroxymethylfurfural (5-HMF), which is known valuable platform chemical. Further, the differences in the yields of IL-obtainable carbohydrates between these species were studied. The highest sugar yields were obtained to glucose in the case of spruce and arabinose in the case of pine sapwood, 12.07 and 7.72 mmol/L, respectively. The highest 5-HMF yield was obtained for spruce heartwood (9.18 mmol/L) with longer treatment time, such as 100h. However, regarding woody biomass, the present work was focused more on the study and analysis of the IL-containing liquid part, wood hydrolysate, after IL-treatment aiming to answer the analysis challenges related to this fraction.

  • 117.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of FtsH proteases in the annual plant Arabidopsis thaliana2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope.

     

    Methods

    • Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers.
    • Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants.

     

    Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins. 

  • 118.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of hypothetical 3D-structures of Arabidopsis thaliana FtsH Proteases with the aim to predict FtsH complex formationManuscript (preprint) (Other academic)
    Abstract [en]

    In Arabidopsis thaliana 12 metallo proteases of the FtsH family are located in the organellar membranes of chloroplasts and mitochondria. While it is known for the Arabidopsis FtsH proteases FtsH1, 2, 5 and 8 to form a hetero–oligomeric, hexameric complex in the chloroplast thylakoid membrane and for FtsH3 and 10 in the inner membrane of mitochondria, no data are available for the remaining (low abundant) FtsH proteases . We compared the sequence identity of amino acids predicted to be relevant in complex formation of FtsH proteases in order to predict additional hetero-oligomeric FtsH complexes. Focus was set on FtsH11 and FtsH4, two subunits that might form a complex in mitochondria. 

  • 119.
    Aigner, Harald
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Searching for substrates of the metallo protease FtsH11 of Arabidopsis thaliana using N-terminal proteomics2012Manuscript (preprint) (Other academic)
    Abstract [en]

    FtsH11 is a membrane-bound metalloprotease localized in mitochondria and in the chloroplast envelope of Arabidopsis thaliana. An ftsh11 knock-out mutant has been shown to develop a chlorotic phenotype in prolonged photoperiods. The proteome of the ftsh11 chloroplast revealed increased abundance of several Calvin cycle enzymes, chaperones and some other proteins, however, none of those proteins could be verified to be an FtsH11 substrate (Harald Aigner, Raik Wagner, Lars L.E. Sjögren, Holger Eubel, A. Harvey Millar, Adrian K. Clarke, Christiane Funk, 2012, manuscript submitted). Here, we have used positional proteomics to identify peptides that report FtsH11 processing events. In this work we were able to identify seven chloroplast-localized proteins that are processed in wild type, but not in ftsh11.  

  • 120.
    Aigner, Harald
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wagner, Raik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjögren, Lars
    Eubel, Holger
    Millar, Harvey
    Clarke, Adrian
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    FtsH11 protease is required for Arabidopsis thaliana to adapt to gtowth in continuous lightManuscript (preprint) (Other academic)
    Abstract [en]

    Continuous light can increase greenhouse food production; however, some of the most important greenhouse horticulture crops are not able to adapt to long photoperiods. Here, we provide evidence that knock-out of the FtsH11 protease causes molecular differences that prevent Arabidopsis thaliana to adapt to prolonged photoperiods. Previously this protease had been shown to be critical for thermotolerance (Chen et al. 2006). We demonstrate that knock-out mutants deficient of FtsH11 develop chlorosis when shifted to continuous light. When grown under normal growth conditions and short days, ftsh11 displayed changes in protein amount of chloroplast proteins involved in the photosynthetic light reaction and the Calvin cycle as well as of the FtsH12 protease. The proteomic changes are accompanied by reduced non-photochemical quenching and faster state transition. A shift to continuous light further enhanced these effects and induced morphological changes of the chloroplast and chlorosis. No changes in the mitochondrial proteome were observed between wild type and ftsh11.

  • 121. Aikio, Anita T.
    et al.
    Pitkänen, Timo
    Fontaine, Dominic
    Dandouras, Iannis
    Amm, Olaf
    Kozlovsky, Alexander
    Vaivads, Andris
    Fazakerley, Andrew
    EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary2008In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 26, p. 87-105Article in journal (Refereed)
  • 122.
    Aikio, Anita T.
    et al.
    Department of Physical Sciences, University of Oulu, Finland.
    Pitkänen, Timo
    Department of Physical Sciences, University of Oulu, Finland.
    Fontaine, Dominic
    CETP/UVSQ, Velizy, France.
    Dandouras, Iannis
    CESR/CNRS, Toulouse, France.
    Amm, Olaf
    Finnish meteorological Institute, Helsinki, Finland.
    Kozlovsky, Alexander
    Department of Physical Sciences, University of Oulu, Finland; Sodankylä Geophysical Observatory, Sodankylä, Finland.
    Vaivads, Andris
    Swedish Institute of Space Physics, Ångströmlaboratoriet, Uppsala, Sweden.
    Fazakerley, Andrew
    Mullard Space Science Laboratory, University College, London, UK.
    EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary2008In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 26, p. 87-105Article in journal (Refereed)
    Abstract [en]

    The dynamics of the polar cap boundary and auroral oval in the nightside ionosphere are studied during late expansion and recovery of a substorm from the region between Tromsø (66.6 degree cgmLat) and Longyearbyen (75.2 degree cgmLat) on 27 February 2004 by using the coordinated EISCAT incoherent scatter radar, MIRACLE magnetometer and Cluster satellite measurements. During the late substorm expansion/early recovery phase, the polar cap boundary (PCB) made zig-zag-type motion with amplitude of 2.5 degree cgmLat and period of about 30 min near magnetic midnight. We suggest that the poleward motions of the PCB were produced by bursts of enhanced reconnection at the near-Earth neutral line (NENL). The subsequent equatorward motions of the PCB would then represent the recovery of the merging line towards the equilibrium state (Cowley and Lockwood, 1992). The observed bursts of enhanced westward electrojet just equatorward of the polar cap boundary during poleward expansions were produced plausibly by particles accelerated in the vicinity of the neutral line and thus lend evidence to the Cowley-Lockwood paradigm.

    During the substorm recovery phase, the footpoints of the Cluster satellites at a geocentric distance of 4.4RE mapped in the vicinity of EISCAT measurements. Cluster data indicate that outflow of H+ and O+ ions took place within the plasma sheet boundary layer (PSBL) as noted in some earlier studies as well. We show that in this case the PSBL corresponded to a region of enhanced electron temperature in the ionospheric F region. It is suggested that the ion outflow originates from the F region as a result of increased ambipolar diffusion. At higher altitudes, the ions could be further energized by waves, which at Cluster altitudes were observed as BBELF (broad band extra low frequency) fluctuations.

    The four-satellite configuration of Cluster revealed a sudden poleward expansion of the PSBL by 2 degree during ˜ 5 min. The beginning of the poleward motion of the PCB was associated with an intensification of the downward FAC at the boundary. We suggest that the downward FAC sheet at the PCB is the high-altitude counterpart of the Earthward flowing FAC produced in the vicinity of the magnetotail neutral line by the Hall effect (Sonnerup, 1979) during a short-lived reconnection pulse.

  • 123. Aikio, Anita T.
    et al.
    Pitkänen, Timo
    Honkonen, Ilja
    Palmroth, Minna
    Amm, Olaf
    IMF effect on the polar cap contraction and expansion during a period of substorms2013In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 31, p. 1021-1034Article in journal (Refereed)
  • 124.
    Aikio, Anita T.
    et al.
    Oulu, Finland.
    Pitkänen, Timo
    Oulu, Finland.
    Honkonen, Ilja
    Helsinki, Finland.
    Palmroth, Minna
    Helsinki, Finland.
    Amm, Olaf
    Helsinki, Finland.
    IMF effect on the polar cap contraction and expansion during a period of substorms2013In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 31, p. 1021-1034Article in journal (Refereed)
    Abstract [en]

    The polar cap boundary (PCB) location and motion in the nightside ionosphere has been studied by using measurements from the EISCAT radars and the MIRACLE magnetometers during a period of four substorms on 18 February 2004. The OMNI database has been used for observations of the solar wind and the Geotail satellite for magnetospheric measurements. In addition, the event was modelled by the GUMICS-4 MHD simulation. The simulation of the PCB location was in a rather good agreement with the experimental estimates at the EISCAT longitude. During the first three substorm expansion phases, neither the local observations nor the global simulation showed any poleward motions of the PCB, even though the electrojets intensified. Rapid poleward motions of the PCB took place only in the early recovery phases of the substorms. Hence, in these cases the nightside reconnection rate was locally higher in the recovery phase than in the expansion phase.

    In addition, we suggest that the IMF Bz component correlated with the nightside tail inclination angle and the PCB location with about a 17-min delay from the bow shock. By taking the delay into account, the IMF northward turnings were associated with dipolarizations of the magnetotail and poleward motions of the PCB in the recovery phase. The mechanism behind this effect should be studied further.

  • 125. Aikio, Anita T.
    et al.
    Pitkänen, Timo
    Kozlovsky, Alexander
    Amm, Olaf
    Method to locate the polar cap boundary in the nightside ionosphere and application to a substorm event2006In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 24, p. 1905-1917Article in journal (Refereed)
  • 126.
    Aisenbrey, Christopher
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bechinger, Burkhard
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Macromolecular Crowding at Membrane Interfaces: Adsorption and Alignment of Membrane Peptides2008In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 375, p. 376-385Article in journal (Refereed)
    Abstract [en]

    Association of proteins to cellular membranes is involved in various biological processes. Various theoretical models have been developed to describe this adsorption mechanism, commonly implying the concept of an ideal solution. However, due to the two-dimensional character of membrane surfaces intermolecular interactions between the adsorbed molecules become important. Therefore previously adsorbed molecules can influence the adsorption behavior of additional protein molecules and their membrane-associated structure. Using the model peptide LAH4, which upon membrane-adsorption can adopt a transmembrane as well as an in-planar configuration, we carried out a systematic study of the correlation between the peptide concentration in the membrane and the topology of this membrane-associated polypeptide. We could describe the observed binding behavior by establishing a concept, which includes intermolecular interactions in terms of a scaled particle theory.

    High surface concentration of the peptide shifts the molecules from an in-planar into a transmembrane conformation, a process driven by the reduction of occupied surface area per molecule. In a cellular context, the crowding-dependent alignment might provide a molecular switch for a cell to sense and control its membrane occupancy. Furthermore, crowding might have pronounced effects on biological events, such as the cooperative behavior of antimicrobial peptides and the membrane triggered aggregation of amyloidogenic peptides.

  • 127.
    Aisenbrey, Christopher
    et al.
    Institut de Chimie Universit0 Louis Pasteur Strasbourg—CNRS, UMR 7177 4, Rue Blaise Pascal, 67000 Strasbourg (France); Max-Planck-Institut f>r Biochemie Am Klopferspitz 18A, 82152 Martinsried (Germany).
    Cusan, Monica
    Lambotte, Stephan
    Jasperse, Pieter
    Georgescu, Julia
    Harzer, Ulrike
    Bechinger, Burkhard
    Specific Isotope Labeling of Colicin E1 and B Channel Domains For Membrane Topological Analysis by Oriented Solid-State NMR Spectroscopy2008In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, no 6, p. 944-951Article in journal (Refereed)
    Abstract [en]

    An approach is presented to selectively label the methionines of the colicin E1 and B channel domains, each about 200 residues in size, and use them for oriented solid-state NMR investigations. By combining site-directed mutagenesis, bacterial overexpression in a methionine auxotroph E. coli strain and biochemical purification, quantitative amounts of the proteins for NMR structural investigations were obtained. The proteins were selectively labeled with 15N at only one, or at a few, selected sites. Multidimensional heteronuclear correlation high-resolution NMR spectroscopy and mass spectrometry were used to monitor the quality of isotopic labeling. Thereafter the proteins were reconstituted into oriented phospholipid bilayers and investigated by proton-decoupled 15N solid-state NMR spectroscopy. The colicin E1 thermolytic fragment that carries a single 15N methionine within its hydrophobic helix 9 region exhibited 15N resonances that are characteristic of helices that are oriented predominantly parallel to the membrane surface at low temperature, and a variety of alignments and conformations at room temperature. This suggests that the protein can adopt both umbrella and pen-knife conformations.

  • 128.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ahlkvist, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, William
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kordas, K
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FIN-20500, Turku/Åbo, Finland.
    Oxidation of α-pinene over gold containing bimetallic nanoparticles supported on reducible TiO2 by DPU method2011In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 392, no 1-2, p. 11-18Article in journal (Refereed)
    Abstract [en]

    A series of bimetallic catalysts Au–M (where M = Cu, Co and Ru) were supported on a reducible TiO2 oxide via deposition-precipitation (DP) method with a slow decomposition of urea as the precipitating agent. The characteristic structural features of the prepared materials were characterized by various physico-chemical techniques such as X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). XPS results indicated the formation of alloyed bimetallic particles on the TiO2 support. TEM results confirmed the fine dispersion of metal nanoparticles on the support with an average particle size in the range of 3–5 nm. An industrially important process, oxy-functionalization of α-pinene was carried out over the prepared bimetallic heterogeneous catalysts under liquid phase conditions. Reaction parameters such as the reaction time, temperature, and the effect of solvent were studied for optimal conversion of α-pinene into verbenone. The major products obtained were verbenone, verbenol, α-pinene oxide and alkyl-pinene peroxide. The activity of the catalysts followed the order; AuCu/TiO2 > AuCo/TiO2 > Cu/TiO2 > Au/TiO2 > AuRu/TiO2. Upon comparison of the various catalysts, AuCu/TiO2 was found to be an active and selective catalyst towards the formation of verbenone. The temperature, nature of the catalysts and the choice of solvents greatly influenced the reaction rate.

  • 129.
    Ajaikumar, Samikannu
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, Anna University, Guindy, Chennai, India.
    Backiaraj, Muthaiah
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Turku/Åbo, Finland.
    Pandurangan, Arumugam
    Transesterification of diethyl malonate with n-butanol over HPWA/MCM-41 molecular sieves2013In: Journal of porous materials, ISSN 1380-2224, E-ISSN 1573-4854, Vol. 20, no 4, p. 951-959Article in journal (Refereed)
    Abstract [en]

    Mesoporous Si-MCM-41 and Al-MCM-41 (Si/Al = 100) materials were synthesized via a hydrothermal method. Three different ratios (10, 20 and 30 wt%) of heteropoly tungstic acid (HPWA) was loaded on Si-MCM-41 by wet impregnation techniques. The characteristic structural features of the prepared materials were studied by various physico-chemical techniques such as X-ray diffraction (XRD), Nitrogen physisorption (BET), temperature programmed desorption of ammonia (TPD) and transmission electron microscopy (TEM). Transesterification of diethyl malonate (DEM) with n-butanol under autogeneous conditions in a temperature range from 50 to 125 °C was selected as the test reaction for the as synthesized materials. The reactants were fed with various mole ratios in order to determine the optimal feed composition leading to maximum yields of transesterified products. The results indicated that the conversion of diethylmalonate depends on the HPWA concentration on the support, temperature, reaction time and mole ratio of the reactants. Further, the catalytic efficiency of HPWA/MCM-41 was compared with that of Al-MCM-41. The solid acid HPWA/MCM-41 catalysts have several advantages in comparison to conventional mineral acid catalysts which are heterogeneous, eco-friendly, highly active and selective in the formation of transesters.

  • 130. Ajuria, Jon
    et al.
    Arnaiz, Maria
    Botas, Cristina
    Carriazo, Daniel
    Mysyk, Roman
    Rojo, Teofilo
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Goikolea, Eider
    Graphene-based lithium ion capacitor with high gravimetric energy and power densities2017In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 363, p. 422-427Article in journal (Refereed)
    Abstract [en]

    Hybrid capacitor configurations are now of increasing interest to overcome the current energy limitations of supercapacitors. In this work, we report a lithium ion capacitor (LIC) entirely based on graphene. On the one hand, the negative-battery-type- electrode consists of a self-standing, binder-free 3D macroporous foam formed by reduced graphene oxide and decorated with tin oxide nanoparticles (SnO2-rGO). On the other hand, the positive-capacitor-type- electrode is based on a thermally expanded and physically activated reduced graphene oxide (a-TEGO). For comparison purposes, a symmetric electrical double layer capacitor (EDLC) using the same activated graphene in 1.5 M Et4NBE4/ACN electrolyte is also assembled. Built in 1 M LiPF6 EC:DMC, the graphene-based LIC shows an outstanding, 10-fold increase in energy density with respect to its EDLC counterpart at low discharge rates (up to 200 Wh kg(-1)). Furthermore, it is still capable to deliver double the energy in the high power region, within a discharge time of few seconds.

  • 131. Akbari, Saieed
    et al.
    Friedland, Shmuel
    Markström, Klas
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Zare, Sanaz
    On 1-sum flows in undirected graphs2016In: The Electronic Journal of Linear Algebra, ISSN 1537-9582, E-ISSN 1081-3810, Vol. 31, p. 646-665Article in journal (Refereed)
    Abstract [en]

    Let G = (V, E) be a simple undirected graph. For a given set L subset of R, a function omega: E -> L is called an L-flow. Given a vector gamma is an element of R-V , omega is a gamma-L-flow if for each v is an element of V, the sum of the values on the edges incident to v is gamma(v). If gamma(v) = c, for all v is an element of V, then the gamma-L-flow is called a c-sum L-flow. In this paper, the existence of gamma-L-flows for various choices of sets L of real numbers is studied, with an emphasis on 1-sum flows. Let L be a subset of real numbers containing 0 and denote L* := L \ {0}. Answering a question from [S. Akbari, M. Kano, and S. Zare. A generalization of 0-sum flows in graphs. Linear Algebra Appl., 438:3629-3634, 2013.], the bipartite graphs which admit a 1-sum R* -flow or a 1-sum Z* -flow are characterized. It is also shown that every k-regular graph, with k either odd or congruent to 2 modulo 4, admits a 1-sum {-1, 0, 1}-flow.

  • 132.
    Akhtari, Mohammad Mehdi
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Accuracy of inverse treatment planning on computed tomography like images derived from magnetic resonance data2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Treatment planning for radiotherapy involves different types of imaging to delineate target volume precisely. The most suitable sources to get 3D information of the patient are the computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT modalities. CT is a modern medical imaging technique that allows three-dimensional treatment planning and conformal treatment techniques. By combining CT images with efficient dosimetry software, accurate patient positioning methods and verification and quality assurance good results can be achieved. The CT images show how the radiation interacts with the material based on each tissue has a different attenuation coefficient, so the data can be used for dose calculations in treatment planning.

    Radiation oncology is therapeutic modality, in which irradiating cancer cells as target is the main goal while always try to limit the dose to healthy tissues and organs. CT images have good potentials because they can provide high geometrical accuracy and electron density information. Having said that, however, using CT images alone for planning does not provide enough information in order to delineate the target volume accurately because the attenuation in soft tissue is fairly constant therefore the soft tissue contrast is poor. Here, (MR) imaging can be very useful since it has superior soft tissue contrast especially in conditions such as prostate cancer, brain lesions, and head and neck tumors. It should be noted that MR images cannot provide electron density information that is required for dose calculations.

    It has been hypothesized that since MRI images have certain benefits in comparison with CT images such as its superior soft tissue contrast which improves contrast resolution between different types of tissues, it would be beneficial to use MRI alone for both target delineation and treatment planning to save time and costs. This was investigated by introducing substitute computed tomography (SCT) which can be interpreted as CT equivalent information obtained by MRI images.

    We used data from five patients with intracranial tumors, and reviewed their initial dosimetric treatment plans that were based solely on CT images, that data was also used to evaluate the dosimetric accuracy of our research treatment plans. Optimization plans that are based on CT images and substitute CT (SCT) was compared with each other in the first step. On the second step the treatment plan that was based on SCT images was transferred to the CT images without any changes and comparisons between the dose calculations on both data sets were made. The delivered dose to planning target volume (PTV) and risk organs was compared.

    Gamma index results between SCT and transferred plan showed no difference in the dose distribution map in PTV. The maximum difference was in the outer contour to the skull. The average and median dose delivered to PTV was within 0.35% difference studying in all patients.

    In conclusion for patients with intracranial tumors the dosimetric accuracy of treatment plans based on SCT and MR images were very accurate, and we demonstrated that it was possible to reach the same dose volume histograms by SCT compared to CT with minimal differences, which were not significant. 

  • 133.
    Akkerman, V'yacheslav
    Umeå University, Faculty of Science and Technology, Physics.
    Turbulent burning, flame acceleration, explosion triggering2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present thesis considers several important problems of combustion theory, which are closely related to each other: turbulent burning, flame interaction with walls in different geometries, flame acceleration and detonation triggering.

    The theory of turbulent burning is developed within the renormalization approach. The theory takes into account realistic thermal expansion of burning matter. Unlike previous renormalization models of turbulent burning, the theory includes flame interaction with vortices aligned both perpendicular and parallel to average direction of flame propagation. The perpendicular vortices distort a flame front due to kinematical drift; the parallel vortices modify the flame shape because of the centrifugal force. A corrugated flame front consumes more fuel mixture per unit of time and propagates much faster. The Darrieus-Landau instability is also included in the theory. The instability becomes especially important when the characteristic length scale of the flow is large.

    Flame interaction with non-slip walls is another large-scale effect, which influences the flame shape and the turbulent burning rate. This interaction is investigated in the thesis in different geometries of tubes with open / closed ends. When the tube ends are open, then flame interaction with non-slip walls leads to an oscillating regime of burning. Flame oscillations are investigated for different flame parameters and tube widths. The average increase in the burning rate in the oscillations is found.

    Then, propagating from a closed tube end, a flame accelerates according to the Shelkin mechanism. In the theses, an analytical theory of laminar flame acceleration is developed. The theory predicts the acceleration rate, the flame shape and the velocity profile in the flow pushed by the flame. The theory is validated by extensive numerical simulations. An alternative mechanism of flame acceleration is also considered, which is possible at the initial stages of burning in tubes. The mechanism is investigated using the analytical theory and direct numerical simulations. The analytical and numerical results are in very good agreement with previous experiments on “tulip” flames.

    The analytical theory of explosion triggering by an accelerating flame is developed. The theory describes heating of the fuel mixture by a compression wave pushed by an accelerating flame. As a result, the fuel mixture may explode ahead of the flame front. The explosion time is calculated. The theory shows good agreement with previous numerical simulations on deflagration-to-detonation transition in laminar flows.

    Flame interaction with sound waves is studied in the geometry of a flame propagating to a closed tube end. It is demonstrated numerically that intrinsic flame oscillations coming into resonance with acoustic waves may lead to violent folding of the flame front with a drastic increase in the burning rate. The flame folding is related to the Rayleigh-Taylor instability developing at the flame front in the oscillating acceleration field of the acoustic wave.

  • 134.
    Akoglu, Canan
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    The relationship between industrial design and interaction design in product development activities2012In: Human Factors in Computing Systems (CHI) International Conference, Austin, TX, USA, May 5-10, 2012 (on DVD), Association for Computing Machinery (ACM), 2012Conference paper (Refereed)
  • 135.
    Akram, Neelam
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    From genes to ecological function in marine bacteria2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacteria in the sea are constantly exposed to environmental challenges (e.g. variations in nutrient concentrations, temperature and light conditions), and therefore appropriate gene expression response strategies to cope with them efficiently are evolved. This thesis investigates some interconnected questions regarding such adaptive strategies employed by marine bacteria.

    The recently discovered ability of bacteria to use the membrane protein proteorhodopsin (PR) to harvest light energy for cell metabolism were investigated in Vibrio sp. AND4 and Dokdonia sp. MED134. PR phototrophy in AND4 promoted survival during starvation, the molecular basis for which were the upregulation of the PR gene by nutrient limitation rather than light. MED134, in contrast, uses PR phototrophy to grow better, and we discovered that the light-stimulated growth was stronger in seawater with the single carbon compound alanine compared to a mixture of complex organic matter. Thus, differences between bacteria in PR gene expression regulation in response to light, nutrients or organic matter quality critically determine the ecological role of PR phototrophy in the sea.

    Current observations that membrane transporters (including PR) are highly expressed in seawater inspired a comparative analysis of transporter distributions in marine bacteria. Totally, 192 transporter families were found in 290 genome-sequenced strains. Consistent differences, but also similarities, in the number of transporters were found between major bacterial groups. Interestingly, sodium transporters were found to be more abundant in PR-containing SAR11. These findings suggest that bacteria have inherently distinctive potentials to adapt to resource variations in the sea.

    To examine links between transcriptional responses and growth of bacteria under controlled environmental settings, a mesocosm phytoplankton bloom experiment was performed. Transcriptional analysis of the microbial community (i.e. metatranscriptomics) revealed 2800 categories of functional genes (SEED functions), of which around 10% were overrepresented in either the bloom mesocosms or the controls. Importantly, these functions indicated potential metabolic mechanisms (e.g. TonB mediated nutrient transport) by which bacteria took advantage of the bloom conditions.

    This thesis combines analyses of model organisms with community analysis and highlights the possibilities to identify important mechanisms that underlie the ecological success of different bacteria in the marine environment. 

  • 136. Aksenova, N.A.
    et al.
    Isakina, A.P.
    Prokhvatilov, A.I.
    Strzhemechny, M.A.
    Soldatov, Alexander V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Structure studies of C60 polymerized at low pressures1997In: Fullerenes: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials, vol. 5, Pennington, NJ: The Electrochemical Society , 1997, p. 687-694Conference paper (Refereed)
    Abstract [en]

    The structure and lattice properties of a polymerized C60 sample were investigated by X-ray powder diffraction over the range from liquid-nitrogen to room temperature. The aim of these studies was to establish the effect of low-pressure compression (up to 1.1 GPa) on the phase composition of the sample, to determine the structure of the phases involved, to obtain the variation of the lattice parameters with temperature, to observe eventual phase transformation in polymerized C60, and to elucidate the evolution of the orientational order with varying temperature. Analysis of the room-temperature diffraction patterns indicates that the sample contained at least two major phases, namely rhombohedral and and tetragonal with the polymerization array close to two-dimensional. Our data obtained on samples annealed at 300 C in the air allow us to conclude that polymerized C60 converts to a mixture of the fcc structure plus a new phase, presumably C60O.

  • 137. Aksmann, Anna
    et al.
    Shutova, Tatiana
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Samuelsson, Göran
    Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC). Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Tukaj, Zbigniew
    The mechanism of anthracene interaction with photosynthetic apparatus: A study using intact cells, thylakoid membranes and PS II complexes isolated from Chlamydomonas reinhardtii2011In: Aquatic Toxicology, ISSN 0166-445X, E-ISSN 1879-1514, Vol. 104, no 3-4, p. 205-210Article in journal (Refereed)
    Abstract [en]

    Intact cells of Chlamydomonas reinhardtii as well as isolated thylakoid membranes and photosystem II complexes were used to examine a possible mechanism of anthracene (ANT) interaction with the photosynthetic apparatus. Since ANT concentrations above 1 mM were required to significantly inhibit the rate of oxygen evolution in PS II membrane fragments it may indicate that the toxicant did not directly interact with this photosystem. On the other hand, stimulation of oxygen uptake by ANT-treated thylakoids suggested that ANT could either act as an artificial electron acceptor in the photosynthetic electron transport chain or function as an uncoupler. Electron transfer from excited chlorophyll to ANT is impossible due to the very low reduction potential of ANT and therefore we propose that toxic concentrations of ANT increase the thylakoid membrane permeability and thereby function as an uncoupler, enhancing electron transport in vitro. Hence, its unspecific interference with photosynthetic membranes in vitro suggests that the inhibitory effect observed on intact cell photosynthesis is caused by uncoupling of phosphorylation. 

  • 138.
    Al Mamoon, Hassan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Evaluation of the separation capacity of different GC columns for tetra- to octachlorinated PCDD/Fs2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 139.
    Alaa, Halawani
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Haibo, Li
    School of Computer Science & Communication, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Template-based Search: A Tool for Scene Analysis2016In: 12th IEEE International Colloquium on Signal Processing & its Applications (CSPA): Proceeding, IEEE, 2016, article id 7515772Conference paper (Refereed)
    Abstract [en]

    This paper proposes a simple and yet effective technique for shape-based scene analysis, in which detection and/or tracking of specific objects or structures in the image is desirable. The idea is based on using predefined binary templates of the structures to be located in the image. The template is matched to contours in a given edge image to locate the designated entity. These templates are allowed to deform in order to deal with variations in the structure's shape and size. Deformation is achieved by dividing the template into segments. The dynamic programming search algorithm is used to accomplish the matching process, achieving very robust results in cluttered and noisy scenes in the applications presented.

  • 140. Ala-aho, P.
    et al.
    Soulsby, C.
    Pokrovsky, O. S.
    Kirpotin, S. N.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Serikova, Svetlana
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Manasypov, R.
    Lim, A.
    Krickov, I.
    Kolesnichenko, L. G.
    Laudon, H.
    Tetzlaff, D.
    Permafrost and lakes control river isotope composition across a boreal Arctic transect in the Western Siberian lowlands2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 3, p. =20-=20, article id 034028Article in journal (Refereed)
    Abstract [en]

    The Western Siberian Lowlands (WSL) store large quantities of organic carbon that will be exposed and mobilized by the thawing of permafrost. The fate of mobilized carbon, however, is not well understood, partly because of inadequate knowledge of hydrological controls in the region which has a vast low-relief surface area, extensive lake and wetland coverage and gradually increasing permafrost influence. We used stable water isotopes to improve our understanding of dominant landscape controls on the hydrology of the WSL. We sampled rivers along a 1700 km South-North transect from permafrost-free to continuous permafrost repeatedly over three years, and derived isotope proxies for catchment hydrological responsiveness and connectivity. We found correlations between the isotope proxies and catchment characteristics, suggesting that lakes and wetlands are intimately connected to rivers, and that permafrost increases the responsiveness of the catchment to rainfall and snowmelt events, reducing catchment mean transit times. Our work provides rare isotope-based field evidence that permafrost and lakes/wetlands influence hydrological pathways across a wide range of spatial scales (10-105 km2) and permafrost coverage (0%-70%). This has important implications, because both permafrost extent and lake/wetland coverage are affected by permafrost thaw in the changing climate. Changes in these hydrological landscape controls are likely to alter carbon export and emission via inland waters, which may be of global significance.

  • 141. Ala-aho, P.
    et al.
    Soulsby, C.
    Pokrovsky, O. S.
    Kirpotin, S. N.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Serikova, Svetlana
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vorobyev, S. N.
    Manasypov, R. M.
    Loiko, S.
    Tetzlaff, D.
    Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape2018In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 556, p. 279-293Article in journal (Refereed)
    Abstract [en]

    Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.

  • 142. Aladi, M.
    et al.
    Bolla, R.
    Cardenas, D. E.
    Veisz, László
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Foldes, I. B.
    Cluster size distributions in gas jets for different nozzle geometries2017In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 12, article id C06020Article in journal (Refereed)
    Abstract [en]

    Cluster size distributions were investigated in case of different nozzle geometries in argon and xenon using Rayleigh scattering diagnostics. Different nozzle geometries result in different behaviour, therefore both spatial- and temporal cluster size distributions were studied to obtain a well-characterized cluster target. It is shown that the generally used Hagena scaling can result in a significant deviation from the observed data and the behaviour cannot be described by a single material condensation parameter. The results along with the nanoplasma model applied to the data of previous high harmonic generation experiments allow the independent measurement of cluster size and cluster density.

  • 143.
    Alainentalo, Lisbeth
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    A Comparison of Tests for Ordered Alternatives With Application in Medicine1997Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A situation frequently encountered in medical studies is the comparison of several treatments with a control. The problem is to determine whether or not a test drug has a desirable medical effect and/or to identify the minimum effective dose. In this Bachelor’s thesis, some of the methods used for testing hypotheses of ordered alternatives are reviewed and compared with respect to the power of the tests. Examples of multiple comparison procedures, maximum likelihood procedures, rank tests and different types of contrasts are presented and the properties of the methods are explored.

    Depending on the degree of knowledge about the dose-responses, the aim of the study, whether the test is parametric or non-parametric and distribution-free or not, different recommendations are given which of the tests should be used. Thus, there is no single test which can be applied in all experimental situations for testing all different alternative hypotheses. 

  • 144.
    Alakpa, Enateri V.
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Saeed, Anwer
    Chung, Peter
    Riehle, Mathis O.
    Gadegaard, Nikolaj
    Dalby, Matthew J.
    Cusack, Maggie
    The Prismatic Topography of Pinctada maxima Shell Retains Stem Cell Multipotency and Plasticity In Vitro2018In: Advanced Biosystems, ISSN 2366-7478, Vol. 2, no 6, article id 1800012Article in journal (Refereed)
    Abstract [en]

    The shell of the bivalve mollusc Pinctada maxima is composed of the calcium carbonate polymorphs calcite and aragonite (nacre). Mother-of-pearl, or nacre, induces vertebrate cells to undergo osteogenesis and has good osteointegrative qualities in vivo. The calcite counterpart, however, is less researched in terms of the response of vertebrate cells. This study shows that isolation of calcite surface topography from the inherent chemistry allows viable long-term culture of bone marrow derived mesenchymal stem cells (MSCs). Self-renewal is evident from the increased gene expression of the self-renewal markers CD63, CD166, and CD271 indicating that cells cultured on the calcite topography maintain their stem cell phenotype. MSCs also retain their multipotency and can undergo successful differentiation into osteoblasts and adipocytes. When directed to adipogenesis, MSCs cultured on prism replicas are more amenable to differentiation than MSCs cultured on tissue culture polystyrene indicating a higher degree of plasticity in MSCs growing on calcite P. maxima prismatic topography. The study highlights the potential of the calcite topography of P. maxima as a biomimetic design for supporting expansion of MSC populations in vitro, which is of fundamental importance if it meets the demands for autologous MSCs for therapeutic use.

  • 145.
    Alam, Md Khorshed
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Fabrication of surface enhanced Raman spectroscopy (SERS) active substrates based on vertically aligned nitrogen doped carbon nanotube forest2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work describes the fabrication and surface enhanced Raman spectroscopy (SERS) characterization of vertically aligned nitrogen (N) doped multi walled carbon nanotube (MWCNT) forests coated by silver (Ag) and gold (Au) nanoparticles. In the present work, the CNT forests were grown from a catalyst metal layer by the chemical vapor deposition (CVD) process at temperature of 800 oC and a physical vapor deposition (PVD) and annealing processes were applied subsequently for the evaporation and diffusion of noble metal nanoparticles on the forest.

    Transistor patterning of 20, 50 and 100 μm were made onto the silicon-oxide (SiO2) wafers through the photolithography process with and without depositing a thickness of 10 nm titanium (Ti) buffer layer on the Si-surfaces. Iron (Fe) and cobalt (Co) were used together to deposite a thickness of 5 nm catalyst layer onto the Single Side Polished (SSP) wafers. As carbon and nitrogen precursor for the CNT growth was used pyridine. Two different treatment times (20 and 60 minutes) in the CVD process determined the CNT forest height. Scanning Electron Microscopy (SEM) imaging was employed to characterize the CNT forest properties and Ag and Au nanoparticle distribution along the CNT walls.

    The existence of “hot spots” created by the Ag and Au nanoparticles through the surface roughness and plasmonic properties was demonstrated by the SERS measurements. Accordingly, the peak intensity at wave number of 1076 cm-1 was picked up from each SERS spectra to establish the Ag- and Au-trend curves with different concentrations of 4-ATP solution. The SERS mapping was also carried out to study the Ag- and Au-coated CNT surface homogeneity and “hot spots” distribution on the CNT surface. The SERS enhancement factors (EF) were calculated by applying an analyte solution of ethanolic 4-ATP on the CNT surface. The calculated values of EF from Ag- and Au-coated CNT forests were 9×106 and 2.7×105 respectively. 

  • 146.
    Alam, Md Khorshed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Vinklarek, Ivo
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Lennart B-Å
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sachl, Radek
    Fluorescence Studies of Lipid Distribution in Bilayers under Oxidative Stress2019In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 116, no 3, p. 508A-508AArticle in journal (Other academic)
  • 147.
    Alanentalo, Tomas
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    Optical projection tomography based 3D-spatial and quantitative assessments of the diabetic pancreas2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The gastrointestinal tract comprises a number of digestive organs including the stomach and pancreas. The stomach is involved in the digestion and short term storage of food while the pancreas is a mixed endocrine and exocrine gland which provides the body with hormones and enzymes essential for nutritional utilisation. The pancreas consists of three different cell lineages, acinar, ductal and endocrine cells. The endocrine cells, organised in the islets of Langerhans, are scattered throughout the exocrine parenchyma and regulate blood glucose levels by production of hormones such as glucagon and insulin.

    The Nkx family of homeodomain proteins controls numerous processes during development. Previous studies have identified two members belonging to the Nkx6 subfamily of Nkx proteins, Nkx6.1 and Nkx6.2. We have described the cloning and embryonic expression pattern of Nkx6.3. All three members of the Nkx6 gene family were shown to be expressed in partially overlapping domains during the development of the gastrointestinal tract and the central nervous system. Nkx6.2 was also identified as a transient marker for pancreatic exocrine cells.

    Analysing gene expression patterns and morphological features in tissues and organs is often performed by stereologic sampling which is a labour-intensive two dimensional approach that rely on certain assumptions when calculating e.g. β-cell mass and islet number in the pancreas. By combined improvements in immunohistochemical protocols, computational processing and tomographic scanning, we have developed a methodology based on optical projection tomography (OPT) allowing for 3D visualisation and quantification of specifically labelled objects within intact adult mouse organs. In the pancreas, this technique allows for spatial and quantitative measurements of total islet number and β-cell mass. We have further developed a protocol allowing for high resolution regional analyses based on global OPT assessments of the pancreatic constitution. This methodology is likely to facilitate detailed cellular and molecular analysis of user defined regions of interest in the pancreas, at the same time providing information on the overall disease state of the gland.

    Type 1 diabetes mellitus (T1D) can occur at any age and is characterized by the marked inability of the pancreas to secrete insulin due to an autoimmune destruction of the insulin producing β-cells. Information on the key cellular and molecular events underlying the recruitment of lymphocytes, their infiltration of the islets of Langerhans and consequent β-cell destruction is essential for understanding the pathogenesis of T1D. Using the developed methodology we have recorded the spatial and quantitative distribution of islet β-cells and infiltrating lymphocytes in the non obese diabetic (NOD) mouse model for T1D. This study shows that the smaller islets, which are predominantly organised in the periphery of the organ, are the first to disappear during the progression of T1D. The larger islets appear more resistant and our data suggest that a compensatory proliferative process is going on side by side with the autoimmune-induced β-cell destruction. Further, the formation of structures resembling tertiary lymphoid organs (TLOs) in areas apparently unaffected by insulitis suggests that local factors may provide cues for the homing of these lymphocytes back to the pancreas.

  • 148.
    Alapää, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Soil geochemical mapping of manganese in Norrbotten: Delineation of the spatial and statistical distribution of manganese and correlated elements in glacial tills2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Information from soil geochemical mapping programmes is useful within a number of different fields including for example mineral exploration and environmental research. The purpose of this thesis was to investigate the relationship between soil metal concentrations and geological factors such as bedrock lithology, structural geology, mineralizations etc. The study used data acquired in association with a nationwide soil geochemical mapping programme conducted by the Geological Survey of Sweden, SGU. These data contained both total element concentrations measured via X-ray fluorescence spectroscopy and acid leached concentrations measured with plasma technique. Basic statistical compilations were made, including classification of element concentrations into percentiles according to SGU standards, calculation of leachability and correlation analyses. Spatial analyses were also done, using GIS-software. The results showed that all investigated elements except zinc had elevated median values for total concentrations in the project area compared to the natural median values. The strongest correlation for total element concentrations was that between iron and cobalt with Spearman ρ=0.88. Furthermore, the results of this study indicated that sampling sites superimposing volcanic rocks contained the highest total concentrations of manganese. The results also suggested that manganese content increased with increasing age of the underlying bedrock. The highest median concentration of 0.80 g/kg was found in Archean rocks. Known mineralizations were often reflected in the form of positive element anomalies in the till geochemistry. The obtained results were also consistent with the average composition of the bedrock. No clear connections with any of the other investigated geological factors could be made.

  • 149.
    Alaqra, Alaa
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Cell-phone Travel Planner GUI for SpaceTime2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Global positioning systems have been having an increasing interest recently and been integrated and used in many applications to service positioning, navigation and travel planning. This project has set to design and test an interface of a travel planner for cell phones. A pre-study was made to investigate other travel planners to help the design of this application that has targeted a user friendly interface that people can use regardless of their background. A special feature, carpooling, has been introduced to ease the environmental, economical, and social aspects of navigation. The test was done as walk-through mockup images case scenarios. The test subjects were pleased with the interface’s friendliness, invoked carpooling issues, presented contradictory opinions regarding the interface's design, and offered future integration with other applications suggestions all of which were discussed. Overall, the test results were positive and few problems with the overall design were identified. A future study with more participants and a deeper analysis of the interface would be one way to further investigate the proposed interface.

  • 150.
    Alatalo, André
    et al.
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Vallgren, Erik
    Umeå University, Faculty of Social Sciences, Department of Informatics.
    Anpassningar till standardisering inom Software Configuration Management: En fallstudie om standardisering inom mjukvarukonfigurationshantering2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Change is inevitable when software is built and deployed. It’s not particularly problematic to manage change if there is just one system. But in a large global IT organization, with several systems and people who develop, problems may arise. If organizations don’t control change, change will control the organization. Software Configuration Management (SCM) is a set of activities to manage change by identifying objects that are likely to change, establishing relationships among them, managing different versions of the objects, controlling the changes imposed and reporting on the changes made. A way to support the work of SCM is to follow standards. A standard can be compared to a type of rule, but also a directive. In this study we examined how a multinational organization applies standards within SCM. We examined the challenges with applying standards. We also examined whether there are deviations from standards, and in such cases why did the deviations arise and what are the following consequences? The study is based on a qualitative case study that employed interviews with developers, IT architects, operations manager and solution leader. The result of this study shows that some of the challenges in applying standards within SCM are: legacy systems, globalization, CMDB and ITSM-related tools (and their processes). The study also shows that standardization within maintenance is complex and that it’s easily breach and forgotten. The study shows that the consequence of this is that the developers must constantly compromise with standards. The result of this compromise is that it’s possible to carry out the business, but the solutions may not meet standards. In this study we concluded that the organization need to direct more attention towards maintenance, and less on new development. 

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