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  • Young, Joanna C.
    et al.
    Univ Alaska, Geophys Inst, Fairbanks, AK 99701 USA..
    Arendt, Anthony
    Univ Alaska, Geophys Inst, Fairbanks, AK 99701 USA.;Univ Washington, Polar Sci Ctr, Appl Phys Lab, Seattle, WA 98195 USA..
    Hock, Regine
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Univ Alaska, Geophys Inst, Fairbanks, AK 99701 USA..
    Pettit, Erin
    Univ Alaska Fairbanks, Dept Geosci, Fairbanks, AK USA..
    The challenge of monitoring glaciers with extreme altitudinal range: mass-balance reconstruction for Kahiltna Glacier, Alaska2018Inngår i: Journal of Glaciology, ISSN 0022-1430, E-ISSN 1727-5652, Vol. 64, nr 243, s. 75-88Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Glaciers spanning large altitudinal ranges often experience different climatic regimes with elevation, creating challenges in acquiring mass-balance and climate observations that represent the entire glacier. We use mixed methods to reconstruct the 1991-2014 mass balance of the Kahiltna Glacier in Alaska, a large (503 km(2)) glacier with one of the greatest elevation ranges globally (264-6108m a. s.l.). We calibrate an enhanced temperature index model to glacier-wide mass balances from repeat laser altimetry and point observations, finding a mean net mass-balance rate of -0.74 mw.e. a(-1)(+/-sigma = 0.04, std dev. of the best-performing model simulations). Results are validated against mass changes from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites, a novel approach at the individual glacier scale. Correlation is strong between the detrended model-and GRACE-derived mass change time series (R-2 = 0.58 and p << 0.001), and between summer (R-2 = 0.69 and p = 0.003) and annual (R-2 = 0.63 and p = 0.006) balances, lending greater confidence to our modeling results. We find poor correlation, however, between modeled glacier-wide balances and recent single-stake monitoring. Finally, we make recommendations for monitoring glaciers with extreme altitudinal ranges, including characterizing precipitation via snow radar profiling.

  • Liang, Feiyan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Englund, Elias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lindberg, Pia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lindblad, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Engineered cyanobacteria with enhanced growth show increased ethanol production and higher biofuel to biomass ratio2018Inngår i: Metabolic engineering, ISSN 1096-7176, E-ISSN 1096-7184, Vol. 46, s. 51-59Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Calvin-Benson-Bassham (CBB) cycle is the main pathway to fix atmospheric CO2 and store energy in carbon bonds, forming the precursors of most primary and secondary metabolites necessary for life. Speeding up the CBB cycle theoretically has positive effects on the subsequent growth and/or the end metabolite(s) production. Four CBB cycle enzymes, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), fructose-1,6/sedoheptulose-1,7-bisphosphatase (FBP/SBPase), transketolase (TK) and aldolase (FBA) were selected to be co-overexpressed with the ethanol synthesis enzymes pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in the cyanobacterium Synechocystis PCC 6803. An inducible promoter, PnrsB, was used to drive PDC and ADH expression. When PnrsB was induced and cells were cultivated at 65 µmol photons m−2 s−1, the RuBisCO-, FBP/SBPase-, TK-, and FBA-expressing strains produced 55%, 67%, 37% and 69% more ethanol and 7.7%, 15.1%, 8.8% and 10.1% more total biomass (the sum of dry cell weight and ethanol), respectively, compared to the strain only expressing the ethanol biosynthesis pathway. The ethanol to total biomass ratio was also increased in CBB cycle enzymes overexpressing strains. This study experimentally demonstrates that using the cells with enhanced carbon fixation, when the product synthesis pathway is not the main bottleneck, can significantly increase the generation of a product (exemplified with ethanol), which acts as a carbon sink.

  • Gabrysch, Katja
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    Thörnblad, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    The greedy walk on an inhomogeneous Poisson process2018Inngår i: Electronic Communications in Probability, ISSN 1083-589X, E-ISSN 1083-589X, Vol. 23, artikkel-id 14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The greedy walk is a deterministic walk that always moves from its current position to the nearest not yet visited point. In this paper we consider the greedy walk on an inhomogeneous Poisson point process on the real line. We prove that the property of visiting all points of the point process satisfies a 0-1 law and determine explicit sufficient and necessary conditions on the mean measure of the point process for this to happen. Moreover, we provide precise results on threshold functions for the property of visiting all points.

  • Kindbom, Karin
    et al.
    Utförare miljöövervakning, Forskningsinstitut, IVL Svenska Miljöinstitutet AB.
    Lidén, Maria
    Adolfsson, Rolf
    Tillämpning av Good Practice Guidance Förstudie2003Rapport (Annet vitenskapelig)
  • Dyrssen, Hannah
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen.
    Ekström, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och sannolikhetsteori.
    Sequential testing of a Wiener process with costly observations2018Inngår i: Sequential Analysis, ISSN 0747-4946, E-ISSN 1532-4176, Vol. 37, nr 1, s. 47-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the sequential testing of two simple hypotheses for the drift of a Brownian motion when each observation of the underlying process is associated with a positive cost. In this setting where continuous monitoring of the underlying process is not feasible, the question is not only whether to stop or to continue at a given observation time but also, if continuing, how to distribute the next observation time. Adopting a Bayesian methodology, we show that the value function can be characterized as the unique fixed point of an associated operator and that it can be constructed using an iterative scheme. Moreover, the optimal sequential distribution of observation times can be described in terms of the fixed point.

  • Berglind, Daniel
    et al.
    Nyberg, Gisela
    Willmer, Mikaela
    Persson, Margareta
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad.
    Wells, Michael
    Forsell, Yvonne
    An eHealth program versus a standard care supervised health program and associated health outcomes in individuals with mobility disability: study protocol for a randomized controlled trial2018Inngår i: Trials, ISSN 1745-6215, E-ISSN 1745-6215, Vol. 19, artikkel-id 258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Young adults with mobility disability (MD) are less likely to engage in regular physical activity (PA) compared with their able-bodied peers and inactive adults with a MD are more likely to report one or more chronic diseases compared to those who are physically active. Despite the vast amount of research published in the field of PA interventions over the past decades, little attention has been focused on interventions aiming to increase PA among individuals with MD. Thus, we propose to compare the effects of an eHealth program compared to a usual care supervised health program on levels of PA and other health behaviors. 

    Methods: The current intervention will use a randomized controlled trial (RCT) design with two treatment groups (an eHealth program and a usual care supervised health program) in young adults with newly acquired MD. In total, 110 young adults (aged 18-40 years) with a MD, acquired within the past 3 years, will be recruited to participate in a 12-week intervention. The primary study outcome is accelerometer-measured time spent in moderate to vigorous PA. Secondary outcomes includes health-related quality of life, depression, stress, fitness, body composition, diet, musculoskeletal pain, motivation to exercise and work ability.

    Discussion: There is a lack of RCTs investigating effective ways to increase levels of PA in young adults with MD. Increased levels of PA among this physically inactive population have the potential to substantially improve health-related outcomes, possibly more so than in the general population. The trial will put strong emphasis on optimizing exercise adherence and investigating feasibility in the two treatment programs. The Ethical Review Board (EPN) at Karolinska Institutet has approved the study (2017/1206-31/1).

  • Moodie, John
    et al.
    Nordiska ministerrådet, Nordregio.
    Teräs, Jukka
    Nordiska ministerrådet, Nordregio.
    Randall, Linda
    Nordiska ministerrådet, Nordregio.
    Building Effective Transnational Partnerships: The Case of Smart Lighting2018Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    This policy brief examines the requirements for building effective transnational partnerships in different policy fields, based on the lessons learned from the recent Lighting Metropolis project – a cross-border innovation venture between Denmark and Sweden that sought to develop smart lighting solutions in urban environments. The brief begins with an overview of this new technology area, before outlining the main opportunities and challenges in the implementation of smart lighting throughout Europe. This is followed by a review of the key findings from Lighting Metropolis, with a focus on assessing the experiences of transnational co-operation identified during the project. Finally, the concluding section outlines a number of recommendations for enhancing transnational collaboration. The policy brief has been prepared by Nordregio as part of the BSR Stars S3 project. It is based on a literature review and interviews conducted with partners involved in Lighting Metropolis.

  • Murina, Victoriia
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS).
    Kasari, Marje
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hauryliuk, Vasili
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Molekylär Infektionsmedicin, Sverige (MIMS). University of Tartu, Institute of Technology, Tartu, Estonia.
    Atkinson, Gemma C.
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Antibiotic resistance ABCF proteins reset the peptidyl transferase centre of the ribosome to counter translational arrest2018Inngår i: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 46, nr 7, s. 3753-3763Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several ATPases in the ATP-binding cassette F (ABCF) family confer resistance to macrolides, lincosamides and streptogramins (MLS) antibiotics. MLS are structurally distinct classes, but inhibit a common target: the peptidyl transferase (PTC) active site of the ribosome. Antibiotic resistance (ARE) ABCFs have recently been shown to operate through direct ribosomal protection, but the mechanistic details of this resistance mechanism are lacking. Using a reconstituted translational system, we dissect the molecular mechanism of Staphylococcus haemolyticus VgaA(LC) and Enterococcus faecalis LsaA on the ribosome. We demonstrate that VgaA(LC) is an NTPase that operates as a molecular machine strictly requiring NTP hydrolysis (not just NTP binding) for antibiotic protection. Moreover, when bound to the ribosome in the NTP-bound form, hydrolytically inactive EQ(2) ABCF ARE mutants inhibit peptidyl transferase activity, suggesting a direct interaction between the ABCF ARE and the PTC. The likely structural candidate responsible for antibiotic displacement by wild type ABCF AREs, and PTC inhibition by the EQ(2) mutant, is the extended inter-ABC domain linker region. Deletion of the linker region renders wild type VgaA(LC) inactive in antibiotic protection and the EQ(2) mutant inactive in PTC inhibition.

  • Hjort, Mattias
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Förare och fordon, FOF.
    Niska, Anna
    Statens väg- och transportforskningsinstitut, Infrastruktur, INFRA, Drift och underhåll, DOU.
    Mätning av cykeldäcks friktionsegenskaper som underlag för simuleringsstudier2018Rapport (Annet vitenskapelig)
    Abstract [sv]

    I detta projekt har mätningar i VTI:s stationära däckprovningsanläggning utförts med ett cykeldäck på asfaltunderlag i syfte att ta fram slipkurvor som beskriver ett cykeldäcks friktionsegenskaper. Mätresultaten har sedan använts för att ta fram en däckparametrisering för simuleringsändamål. Följande däckparametrar har mätts: cornering stiffness, camber stiffness, brake slip stiffness och lateral relaxationslängd.

    Det testade däcket genererade en maximal friktionsnivå på ungefär 1,0 på asfalten. Typiska värden på däckparametrarna var: normerad cornering stiffness 0,3; normerad camber stiffness 0,01; normerad brake slip stiffness 250. Jämfört med de få tidigare publicerade mätningar på cykeldäck så är cornering stiffness generellt ca 50 procent högre än vad som hittills rapporterats. Värdena för camber stiffness motsvarar väl de värden som en studie av racingdäck uppvisat, men är 25–50 procent lägre än värden uppmätta på mer normala däck i en annan studie. För brake slip stiffness finns inga tidigare mätningar att jämföra med. Mätning av relaxationslängden påverkades tyvärr av problem med mätutrustningen och vi kunde inte bestämma denna med önskad noggrannhet. Från mätningarna uppskattar vi relaxationslängden till 200–300 mm för det testade däcket, vilket är en faktor 2–3 ggr större än vad som rapporterades i den enda studie som tidigare mätt relaxationslängd för cykeldäck.

  • Gould, Ernest
    et al.
    Aix Marseille Univ, EPV, IRD 190, INSERM 1207,EHESP, Marseille, France..
    Pettersson, John
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi. Norwegian Inst Publ Hlth, Domain Infect Control & Environm Hlth, Dept Infect Dis Epidemiol & Modelling Mol Biol, Oslo, Norway..
    Higgs, Stephen
    Kansas State Univ, Diagnost Med & Pathobiol, Manhattan, KS 66506 USA.;Kansas State Univ, KS Biosecur Res Inst, Manhattan, KS 66506 USA..
    Charrel, Remi
    Aix Marseille Univ, EPV, IRD 190, INSERM 1207,EHESP, Marseille, France.;Inst Hosp Univ Mediterranee Infect, APHM Publ Hosp Marseille, Marseille, France..
    de Lamballerie, Xavier
    Aix Marseille Univ, EPV, IRD 190, INSERM 1207,EHESP, Marseille, France.;Inst Hosp Univ Mediterranee Infect, APHM Publ Hosp Marseille, Marseille, France..
    Emerging arboviruses: Why today?2017Inngår i: ONE HEALTH, ISSN 2352-7714, Vol. 4, s. 1-13Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The recent global (re)emergence of arthropod-borne viruses (arboviruses), such as chikungunya and Zika virus, was widely reported in the media as though it was a new phenomenon. This is not the case. Arboviruses and other human microbial pathogens have been (re)emerging for centuries. The major difference today is that arbovirus emergence and dispersion are more rapid and geographically extensive, largely due to intensive growth of global transportation systems, arthropod adaptation to increasing urbanisation, our failure to contain mosquito population density increases and land perturbation. Here we select examples of (re)emerging pathogenic arboviruses and explain the reasons for their emergence and different patterns of dispersal, focusing particularly on the mosquito vectors which are important determinants of arbovirus emergence. We also attempt to identify arboviruses likely to (re)emerge in the future.

  • Lønnebotn, Marianne
    et al.
    Svanes, Cecilie
    Igland, Jannicke
    Franklin, Karl A.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Accordini, Simone
    Benediktsdóttir, Bryndís
    Bentouhami, Hayat
    Blanco, José A. G.
    Bono, Roberto
    Corsico, Angelo
    Demoly, Pascal
    Dharmage, Shyamali
    Dorado Arenas, Sandra
    Garcia, Judith
    Heinrich, Joachim
    Holm, Mathias
    Janson, Christer
    Jarvis, Debbie
    Leynaert, Bénédicte
    Martinez-Moratalla, Jesús
    Nowak, Dennis
    Pin, Isabelle
    Raherison-Semjen, Chantal
    Sánchez-Ramos, Jose Luis
    Schlunssen, Vivi
    Skulstad, Svein Magne
    Dratva, Julia
    Real, Francisco Gómez
    Body silhouettes as a tool to reflect obesity in the past2018Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, nr 4, artikkel-id e0195697Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Life course data on obesity may enrich the quality of epidemiologic studies analysing health consequences of obesity. However, achieving such data may require substantial resources. We investigated the use of body silhouettes in adults as a tool to reflect obesity in the past. We used large population-based samples to analyse to what extent self-reported body silhouettes correlated with the previously measured (9-23 years) body mass index (BMI) from both measured (European Community Respiratory Health Survey, N = 3 041) and selfreported (Respiratory Health In Northern Europe study, N = 3 410) height and weight. We calculated Spearman correlation between BMI and body silhouettes and ROC-curve analyses for identifying obesity (BMI >= 30) at ages 30 and 45 years. Spearman correlations between measured BMI age 30 (+/- 2y) or 45 (+/- 2y) and body silhouettes in women and men were between 0.62-0.66 and correlations for self-reported BMI were between 0.58-0.70. The area under the curve for identification of obesity at age 30 using body silhouettes vs previously measured BMI at age 30 (+/- 2y) was 0.92 (95% CI 0.87, 0.97) and 0.85 (95% CI 0.75, 0.95) in women and men, respectively; for previously self-reported BMI, 0.92 (95% CI 0.88, 0.95) and 0.90 (95% CI 0.85, 0.96). Our study suggests that body silhouettes are a useful epidemiological tool, enabling retrospective differentiation of obesity and non-obesity in adult women and men.

  • Disputas: 2018-06-07 10:00 F3, Stockholm
    Sundarapandian, Sembian
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Strong blast wave interaction with multiphase media2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The interaction of a blast wave propagating in air with different fluids like water column, aqueous foam and thermal/density inhomogeneity have been studied both experimentally and numerically. The blast waves were generated at atmospheric conditions in a newly constructed exploding wire facility. For fixed capacitance and wire size, the intensity of the shock front (measured typically at 200 mm from the wire explosion plane) was varied by controlling the charges stored in the capacitor and the size of the test section. Qualitative features of the interaction were captured using shadowgraph technique. Numerical simulations were performed to better analyze and understand the flow features observed in experiments. The main points across each fluid interactions are as follow:

    Water column: A new technique was implemented to create highly repeatable, properly shaped, large diameter water column. The impact of a blast wave with shock Mach number ranging from 1.75 to 2.4 on a 22 mm diameter water column resulted in a complex system of waves propagating inside the column. Due to the concave boundary of the downstream interface, the reflected expansion wave naturally focused at a point before travelling upstream resulting in the generation of large negative pressures leading to nucleation of cavitation bubbles. Through high speed photography, various aspects of the flow features were discussed qualitatively and quantitatively. With the aid of numerical simulation, the effect of size of water column and shock strength on the maximum attainable negative pressures in the absence of cavitation were quantified.

    Aqueous foam: The performance of various aqueous foam barrier configurations on the attenuation of externally generated blast wave peak pressure was examined. Here a blast wave with shock Mach number 4.8 was allowed to interact with an aqueous foam barrier of initial liquid fraction 0.1. The dominant process responsible for reduction of peak pressure was the `catching up' of the rarefaction wave with the wave front travelling in the foam barrier. Additional reduction was provided by the impedance mismatch factor at the foam-air interface which was further exploited to achieve greater reduction. A simple numerical model treating the foam by a pseudo-gas approach was used for re-constructing the experimental results.

    Density inhomogeneity: The unstable evolution of a 2D elongated, elliptically-shaped inhomogeneity embedded in ambient air and aligned both normal and at an angle to the incident plane blast wave of impact Mach number 2.15 was studied. The inhomogeneity was created on the basis of `Joule heating' wherein heat produced by a current carrying wire was used to heat its surrounding air. Two counter-rotating vortices primarily due to Richtmyer-Meshkov instability (RMI) and a train of vortices primarily due to Kelvin-Helmholtz instability (KHI) were observed for two different inclination angles. Similarly circulation, calculated from numerical simulation solving Navier-Stokes equation, was also found to vary from a linear to a quadratic function when the inhomogeneity was inclined.

  • Rodhe, Lena
    et al.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Alverbäck, Adam
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Ascue, Johnny
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Edström, Mats
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Nordberg, Åke
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Pizzul, Leticia
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Tersmeden, Marianne
    RISE - Research Institutes of Sweden, Biovetenskap och material, Jordbruk och livsmedel.
    Åtgärder för att minimera växthusgasutsläpp från lager med rötad och orötad gödsel2018Rapport (Annet vitenskapelig)
    Abstract [sv]

    Kunskap om effektiva, funktionella och ekonomiska åtgärder krävs för att säkerställa små utsläpp av växthusgaser från lager med både orötad och rötad gödsel. I detta treåriga projekt har olika tänkbara åtgärder i flytgödsellager studerats genom mätning av växthusgaserna metan och lustgas under sommarförhållanden. Åtgärder som förlängd utrötningstid och surgörning av gödsel med svavelsyra, har utvärderats i RISE pilotskaleanläggning för lagring av flytgödsel. Åtgärder för att minska lustgasemissioner bildat i svämtäcke på gödselyta i ett fullskalelager har studerats på gårdsnivå. Kompletterande teoretiska beräkningar har utförts för att bedöma effekten av att täcka flytgödsellager samt laboratoriestudier av temperaturens påverkan på metangas-emissionerna.

    Grundläggande är att temperaturen har stor betydelse, vilket visades i laboratorieskalan. Vid ökad temperatur ökade metanproduktionen exponentiellt för rötad gödsel medan för orötad gödsel var ökningen betydligt mindre. De teoretiska värmebalansberäkningarna för lager med gödsel visade att beskuggning av gödselytan eller täckning av lager med vitt tak bör kunna reducera denna uppvärmning kraftigt på våren eftersom värmeinstrålningen från solljus till gödsellager kan förklarade största delen av gödselns uppvärmning.

    Studierna under första och sista året visade att metanemissionerna var signifikant större från gödseln när den var rötad än om den var orötad. Sammanlagda förlusterna av metan var 2,5 respektive fyra gånger så höga från den rötade gödseln under sommarlagringarna (ca fyra månader). Det betyder att det är speciellt viktigt att sätta in åtgärder vid lagring av rötad gödsel för att begränsa utsläppen av metan och därmed minska klimatpåverkan.

    En åtgärd för att få lägre metanemissioner från den rötade gödseln är att förlänga utrötningstiden, dvs. den hydrauliska uppehållstiden i rötkammaren. Studierna år 1 visar att vid en fördubblad uppehållstid, 48 dagar istället för 24 dagar, minskade metanemissionerna från lagret med 30 procent. På gårdar med rötningsanläggningar är ett gastätt tak med uppsamling av biogasen också en bra åtgärd för att effektivisera anläggningen och förhindra utsläpp av klimatgaser från lagret.

    Surgörning av flytgödsel med svavelsyra praktiseras främst i Danmark för att minska ammoniakavgången från flytgödsel, i stall, lager och vid spridning. Resultaten visar att det är en mycket effektiv metod för att minimera metangasemissionerna från lager med en reduktion med mer än 90 procent både för orötad och för rötad gödsel. Speciellt för gödselslag där det inte bildas naturligt svämtäcke kan surgörning vara intressant för att minska både ammoniak- och metanemissioner.

    Åtgärder som surgörning av svämtäcket för att minska lustgasemissioner visade sig inte behövas eftersom lustgasemissionerna var relativt låga, trots att svämtäcket var bortåt en halv meter tjockt. Den finhackade halmen som användes som strö, bildade ett slätt och tätt svämtäcke på gödselytan vilket troligen hämmande lustgasbildningen, till följd av att luften inte kunde penetrera skiktet. Så finhackningen av halmströ kan eventuellt vara i sig en tänkbar åtgärd, vilket också kan minska ströåtgången.

    Metanproduktionen från en rötkammare är ofta svår att mäta, och beräknas därför ofta indirekt utifrån producerad elproduktion. Ett exempel på nyckeltal för att visa klimateffektiviteten hos anläggningen visas där metanemissionerna från lager under sommaren var 10,2 % av producerad mängd metan från rötkammare vid enstegsrötning under 24 dagar respektive 5,5 % vid tvåstegsrötning under 48 dagar. På årsbasis blir procenttalen betydligt lägre eftersom emissionerna är låga under vintern.

  • Disputas: 2018-06-13 13:15 Room Å4001, Uppsala
    Stegeby, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi.
    MATTER-ANTIMATTER INTERACTIONS: The hydrogen-antihydrogen system and antiproton-matter interactions2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Ever since antiparticles were discovered their nature has been something of a mystery. They were postulated to be identical to regular particles except for having opposite charge, but this would imply that an equal amount of antiparticles and particles should have been created at the beginning of time. However, everywhere we look the Universe seems to be constituted of regular particles, giving rise to the question whether there is something else that differentiates antiparticles from regular particles, or if there is something amiss in the Standard Model of particle physics.

    This thesis focuses on a central system of study in this field, the hydrogen-antihydrogen system and the theory surrounding it, as well as an expansion into systems with an antiproton interacting with small molecules, bridging the fields of quantum physics and quantum chemistry.

    Methods expanding on the Born-Oppenheimer approximation for the interaction between the two atoms are presented. The resulting 2-body interaction potential is then used for creating a part of the basis in a non-adiabatic 4-body method in order to look for resonance states whose existence could impact cross-sections of hydrogen-antihydrogen scattering. The eigenfunctions obtained from the non-adiabatic method are used by extracting the 2-body hadronic density function and comparing it to the adiabatic wave function, for measuring the adiabaticity of the hydrogen-antihydrogen system.

    The antiproton-matter interaction is first investigated by a quantum dynamical approach of an antiproton scattering on molecular hydrogen, common products in high-energy collision experiments, continued by a study of the potential energy surfaces of an antiproton interacting with a range of functional groups present in the human body.

  • Engel, Fabian
    et al.
    Farrell, Kaitlin J.
    McCullough, Ian M.
    Scordo, Facundo
    Denfeld, Blaize A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Dugan, Hilary A.
    de Eyto, Elvira
    Hanson, Paul C.
    McClure, Ryan P.
    Nöges, Peeter
    Nöges, Tiina
    Ryder, Elizabeth
    Weathers, Kathleen C.
    Weyhenmeyer, Gesa A.
    A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters2018Inngår i: The Science of Nature: Naturwissenschaften, ISSN 0028-1042, E-ISSN 1432-1904, Vol. 105, artikkel-id 25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO2) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of 0.70(-0.31)(+0.27) 1.52(-0.90)(+1.09) Pg C yr(-1) depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.

  • Disputas: 2018-06-12 13:00 E3, Stockholm
    Carlson, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    Abelian affine group schemes, plethories, and arithmetic topology2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In Paper A we classify plethories over a field of characteristic zero. All plethories over characteristic zero fields are ``linear", in the sense that they are free plethories on a bialgebra. For the proof of this classification we need some facts from the theory of ring schemes where we extend previously known results. We also give a classification of plethories with trivial Verschiebung over a perfect field k of characteristic p>0.

    In Paper B we study tensor products of abelian affine group schemes over a perfect field k. We first prove that the tensor product G_1 \otimes G_2 of two abelian affine group schemes G_1,G_2 over a perfect field k exists. We then describe the multiplicative and unipotent part of the group scheme G_1 \otimes G_2. The multiplicative part is described in terms of Galois modules over the absolute Galois group of k. In characteristic zero the unipotent part of G_1 \otimes G_2 is the group scheme whose primitive elements are P(G_1) \otimes P(G_2). In positive characteristic, we give a formula for the tensor product in terms of Dieudonné theory. 

    In Paper C we use ideas from homotopy theory to define new obstructions to solutions of embedding problems and compute the étale cohomology ring of the ring of integers of a totally imaginary number field with coefficients in Z/2Z. As an application of the obstruction-theoretical machinery, we give an infinite family of totally imaginary quadratic number fields such that Aut(PSL(2,q^2)), for q an odd prime power, cannot be realized as an unramified Galois group over K, but its maximal solvable quotient can. 

    In Paper D we compute the étale cohomology ring of an arbitrary number field with coefficients in Z/nZ for n an arbitrary positive integer. This generalizes the computation in Paper C. As an application, we give a formula for an invariant defined by Minhyong Kim.

  • Aaboud, M.
    et al.
    Univ Mohamed Premier, Fac Sci, Oujda, Morocco.;LPTPM, Oujda, Morocco..
    Bergeås Kuutmann, Elin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Bokan, Petar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik. Georg August Univ, Phys Inst 2, Gottingen, Germany.
    Brenner, Richard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Ekelöf, Tord
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Ellert, Mattias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Ferrari, Arnaud
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Gradin, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Isacson, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Mårtensson, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Öhman, Henrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Sales De Bruin, Pedro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Högenergifysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Measurement of differential cross-sections of a single top quark produced in association with a W boson at √s=13TeV with ATLAS2018Inngår i: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, nr 3, artikkel-id 186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The differential cross-section for the production of a W boson in association with a top quark is measured for several particle-level observables. The measurements are performed using 36.1 fb(-1) of pp collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase space defined by the presence of two charged leptons and exactly one jet matched to a b-hadron, and are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators.

  • Disputas: 2018-06-08 13:00 Sal X, Uppsala
    Larsson, Germund
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Fakulteten för utbildningsvetenskaper, Institutionen för pedagogik, didaktik och utbildningsstudier.
    Förbrytelser och förvisningar: Bestraffningssystemet i de svenska läroverken 1905–19612018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The aim of this dissertation is to analyse the system of punishment at the upper secondary schools in Sweden during the twentieth century. The main research question is: how did the system of punishment function and change from 1905 to 1961? The investigations concentrate on the offences committed, the spatial features of the jurisdiction, the agents involved, as well as the systems of meaning that underscored the penal process. The analysis is mainly founded upon an extensive source material comprehending all expulsion cases at the upper secondary schools during the period.

    The dissertation enriches our understanding of how the system of punishment operated during the twentieth century. The pupil and his or her morals and conduct were at the heart of the system of punishment. It is shown that the hardest punishment, the expulsion, was not only passed for the most severe offences, but also for more banal infractions. Furthermore, the juridical system of the upper secondary schools stretched far beyond the physical milieu of the school yard. Offences committed in the public arena of the town, as well as the private institution of the household, stood grounds for excluding a pupil. Additionally, the relative importance of different types of agents that enacted the system changed over time. Headmasters and teachers were successively accompanied by new agents such as school physicians, the child protection agency as well as modern law enforcement personnel. Finally, the rationality – the historically specific system of meaning underlying the judgment of pupils’ offences – behind the decisions to issue the hardest punishment is examined. Ideas of conduct relating to gender and social class, values concerning truthfulness and deceitfulness, as well as ideas of physical attributes and their connection to intelligence and mental decease, all played parts in the examination of the offending pupils. In the end, the dissertation argues that the system of punishment was something more, and something else, then a mere part of the pedagogical practise of the upper secondary schools. In the system of punishment, internal school traditions converged with partially contradictory tendencies within society at large.

  • Disputas: 2018-06-12 09:00 Å2001, Uppsala
    Spiegelberg, Jakob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Signal Processing Tools for Electron Microscopy2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The detection of weak signals in noisy data is a problem which occurs across various disciplines. Here, the signal of interest is the spectral signature of the electron magnetic chiral dichroism (EMCD) effect. In principle, EMCD allows for the measurement of local magnetic structures in the electron microscope, its spatial resolution, versatility and low hardware requirements giving it an eminent position among competing measurement techniques. However, experimental shortcomings as well as intrinsically low signal to noise ratio render its measurement challenging to the present day.   

    This thesis explores how posterior data processing may aid the analysis of various data from the electron microscope. Following a brief introduction to different signals arising in the microscope and a yet briefer survey of the state of the art of EMCD measurements, noise removal strategies are presented. Afterwards, gears are shifted to discuss the separation of mixed signals into their physically meaningful source components based on their assumed mathematical characteristics, so called blind source separation (BSS).    

    A data processing workflow for detecting weak signals in noisy spectra is derived from these considerations, ultimately culminating in several demonstrations of the extraction of EMCD signals. While the focus of the thesis does lie on data processing strategies for EMCD detection, the approaches presented here are similarly applicable in other situations. Related topics such as the general analysis of hyperspectral images using BSS methods or the fast analysis of large data sets are also discussed.

  • Disputas: 2018-06-11 13:00 Humanistiska teatern, Uppsala
    Petek, Nik
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för arkeologi och antik historia.
    Archaeological Perspectives on Risk and Community Resilience in the Baringo Lowlands, Kenya2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This historical ecological research provides a detailed insight into the risk avoidance and resilience building strategies in the Lake Baringo basin in Kenya through the lens of archaeology. It explores how changes in subsistence, habitation, and landscape shaped each other and how that affected the available strategies of risk avoidance and resilience building. While the focus is on the history and archaeology of the Ilchamus, a Maa community currently occupying the area, the research additionally investigated the late Holocene of the Baringo lowlands to provide a basis for the discussion on risk and resilience. A combination of remote sensing, foot surveys, excavation, and spatial statistic methods establishes a culture history for the region, showing that the Lake Baringo basin has been part of the pastoralist cultural sphere for the past three millennia and that the Rift Valley bottom possibly acted as a frontier between different archaeological cultures. By the end of the 18th or the beginning of the 19th century the area was occupied by Ilchamus. They established densely aggregated settlements and a vast irrigation system in order to enmesh themselves into the local, regional, and global exchange system. Through the exchange system, they would ensure their ‘social survival’ and build social contracts as part of their resilience building strategies, which continued to be practiced even as the Ilchamus subsistence and habitation practices as well as the political situation changed. However, as archaeological assemblages and ethnoarchaeological and historical data show, throughout their 200-year history community conformity and consolidation were central forces in the formation of an Ilchamus identity and a strong community resilience.

    The environmental degradation of the Lake Baringo area has been the subject of studies for almost a century with the subsistence practices of the local communities seen as a key cause for it. This research moves beyond blame but instead explores the options available and choices taken by the Ilchamus community in specific environmental and political contexts. I hope that this thesis provides some insights into new avenues of exploration of how we can develop and strengthen the resilience of vulnerable communities, such as Ilchamus.

  • Meunier, Cécile
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Hosseini, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Heidari, Nahid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Maryush, Zaywa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Johannesson, Hanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi.
    Multilevel Selection in the Filamentous Ascomycete Neurospora tetrasperma2018Inngår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 191, nr 3, s. 290-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The history of life has been driven by evolutionary transitions in individuality, that is, the aggregation of autonomous individuals to form a new, higher-level individual. The fungus Neurospora tetrasperma has recently undergone an evolutionary transition in individuality from homokaryosis (one single type of nuclei in the same cytoplasm) to heterokaryosis (two genetically divergent and free-ranging nuclear types). In this species, selection can act at different levels: while nuclei can compete in their replication and transmission into short-lived asexual spores, at the level of the heterokaryotic individual, cooperation between nuclear types is required to produce the long-lived sexual spores. Conflicts can arise between these two levels of selection if the coevolution between nuclear types is disrupted. Here, we investigated the extent of multilevel selection in three strains of N. tetrasperma. We assessed the ratio between nuclear types under different conditions and measured fitness traits of homo- and heterokaryotic mycelia with varying nuclear ratios. We show that the two nuclei have complementary traits, consistent with division of labor and cooperation. In one strain, for which a recent chromosomal introgression was detected, we observed the occurrence of selfish nuclei, enjoying better replication and transmission than sister nuclei at the same time as being detrimental to the heterokaryon. We hypothesize that introgression has disrupted the coevolution between nuclear types in this strain.

  • Kuhne, Philipp
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Armakavicius, Nerijus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Stanishev, Vallery
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Herzinger, Craig M,
    J. A. Woollam Company, Inc., Lincoln, NE, USA.
    Schubert, Mathias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications2018Inngår i: IEEE Transactions on Terahertz Science and Technology, ISSN 2156-342X, Vol. 8, nr 3, s. 257-270Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a terahertz (THz) frequency-domain spectroscopic ellipsometer design that suppresses formation of standing waves by use of stealth technology approaches. The strategy to suppress standing waves consists of three elements geometry, coating, and modulation. The instrument is based on the rotating analyzer ellipsometer principle and can incorporate various sample compartments, such as a superconducting magnet, in situ gas cells, or resonant sample cavities, for example. A backward wave oscillator and three detectors are employed, which permit operation in the spectral range of 0.1–1 THz (3.3–33 cm−1 or 0.4–4 meV). The THz frequency-domain ellipsometer allows for standard and generalized ellipsometry at variable angles of incidence in both reflection and transmission configurations. The methods used to suppress standing waves and strategies for an accurate frequency calibration are presented. Experimental results from dielectric constant determination in anisotropic materials, and free charge carrier determination in optical Hall effect (OHE), resonant-cavity enhanced OHE, and in situ OHE experiments are discussed. Examples include silicon and sapphire optical constants, free charge carrier properties of two-dimensional electron gas in a group III nitride high electron mobility transistor structure, and ambient effects on free electron mobility and density in epitaxial graphene.

  • Lindelöw, Camilla
    Södertörns högskola, Södertörns högskolebibliotek.
    Utvärdering och utforskande2018Inngår i: Världen där utanför: bibliotekariens roll som omvärldsbevakare och analytiker / [ed] Marja Haapalainen ; Christine Wallén, Stockholm: Kungliga biblioteket , 2018, s. 101-120Kapittel i bok, del av antologi (Annet vitenskapelig)
  • Codemo, Mario
    et al.
    Muschiol, Sandra
    Iovino, Federico
    Nannapaneni, Priyanka
    Plant, Laura
    Wai, Sun Nyunt
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR).
    Henriques-Normark, Birgitta
    Immunomodulatory Effects of Pneumococcal Extracellular Vesicles on Cellular and Humoral Host Defenses2018Inngår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 9, nr 2, artikkel-id e00559-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gram-positive bacteria, including the major respiratory pathogen Streptococcus pneumoniae, were recently shown to produce extracellular vesicles (EVs) that likely originate from the plasma membrane and are released into the extracellular environment. EVs may function as cargo for many bacterial proteins, however, their involvement in cellular processes and their interactions with the innate immune system are poorly understood. Here, EVs from pneumococci were characterized and their immunomodulatory effects investigated. Pneumococcal EVs were protruding from the bacterial surface and released into the medium as 25 to 250 nm lipid stained vesicles containing a large number of cytosolic, membrane, and surface-associated proteins. The cytosolic pore-forming toxin pneumolysin was significantly enriched in EVs compared to a total bacterial lysate but was not required for EV formation. Pneumococcal EVs were internalized into A549 lung epithelial cells and human monocyte-derived dendritic cells and induced proinflammatory cytokine responses irrespective of pneumolysin content. EVs from encapsulated pneumococci were recognized by serum proteins, resulting in C3b deposition and formation of C5b-9 membrane attack complexes as well as factor H recruitment, depending on the presence of the choline binding protein PspC. Addition of EVs to human serum decreased opsonophagocytic killing of encapsulated pneumococci. Our data suggest that EVs may act in an immunomodulatory manner by allowing delivery of vesicle-associated proteins and other macromolecules into host cells. In addition, EVs expose targets for complement factors in serum, promoting pneumococcal evasion of humoral host defense.

    Importance: Streptococcus pneumoniae is a major contributor to morbidity and mortality worldwide, being the major cause of milder respiratory tract infections such as otitis and sinusitis and of severe infections such as community-acquired pneumonia, with or without septicemia, and meningitis. More knowledge is needed on how pneumococci interact with the host, deliver virulence factors, and activate immune defenses. Here we show that pneumococci form extracellular vesicles that emanate from the plasma membrane and contain virulence properties, including enrichment of pneumolysin. We found that pneumococcal vesicles can be internalized into epithelial and dendritic cells and bind complement proteins, thereby promoting pneumococcal evasion of complement-mediated opsonophagocytosis. They also induce pneumolysin-independent proinflammatory responses. We suggest that these vesicles can function as a mechanism for delivery of pneumococcal proteins and other immunomodulatory components into host cells and help pneumococci to avoid complement deposition and phagocytosis-mediated killing, thereby possibly contributing to the symptoms found in pneumococcal infections.

  • Disputas: 2018-06-12 14:00 Hörsal 2, Uppsala
    Grant, Michael
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Samhällsvetenskapliga fakulteten, Företagsekonomiska institutionen. Uppsala University.
    MAKING ACQUISITIONS2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis examines acquisition-making, that is, activities and events leading up to the completion or cancellation of an acquisition. Acquisition-making involves people, from various areas of expertise, who are managed by and organized in what in this thesis is called a professional acquisition organization (PAO). The PAO is a small task force consisting of people from the acquirer and advisers assigned to make the acquisition. In addition to the PAO, decision-makers are obviously involved. However, the thesis especially examines the PAO’s activities. The setting is serial acquirers in which the PAO is managed by a special group of people appointed for this task.

    Acquisition-making is examined through a literature review of qualitative process research in M&A and three explorative case studies. These encompass a study of the role of the PAO in acquisition decision-making; a study of how strategic and financial rationales are produced; and a study of the role of management control systems in secret organizations such as PAOs.

    The findings of these studies contribute to our knowledge about how acquisitions are made in three ways. First, the findings show how the PAO plays a critical role in acquisition decision-making, emanating from a division of labor between the PAO and decision-makers. This enables the PAO to enhance or attenuate the perceived benefits of an acquisition when informing decision-makers. The respective purposes would be to receive approval for the acquisition, or to show improved performance after it is made. Second, the findings show how the key reasons for making an acquisition, through the strategic and financial rationales, are made by judgments based on intuitive expertise. Thus, the study provides an explanation for and understanding of how concepts such as cash flows are used in evaluating acquisitions. This implies that the expertise of the practitioners producing the strategic and financial rationales is of utmost importance for acquisition decisions, probably more so than the tools used. Third, the findings show that management control systems are important for how confidential information is concealed and made visible in acquisition-making, revealing different categories of secrets to different insiders and outsiders throughout acquisition-making.

  • Grimelius, Lars
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Experimentell och klinisk onkologi.
    Åkerström, Göran
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Endokrinkirurgi.
    Biographical item: "Henry Johansson in memoriam" in Upsala Journal Of Medical Sciences, vol 122, Issue: 4, pp 260-2612017Annet (Annet (populærvitenskap, debatt, mm))
  • Nele Mäger, Katrin
    et al.
    Tallinn University of Technology, Estonia.
    Just, Alar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Development of Design Equations for the Component Additive Method for Paroc eXtra2017Rapport (Annet vitenskapelig)
    Abstract [en]

    This report details the development of effective thermal properties and design equations for Paroc eXtra which can be used for the improved component additive method for fire design of timber structures.  The results are validated with full scale fire tests where such reports are available. 

  • Fotrousi, Farnaz
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    Seyff, Norbert
    University of Applied Sciences and Arts Northwestern Switzerland, CHE.
    Börstler, Jürgen
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för programvaruteknik.
    Ethical Considerations in Research on User Feedback2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Collecting and using user feedback as a method to support requirements engineering, might undermine user rights. This becomes apparent when looking at related areas, e.g., research in user experience, where collecting user feedback also plays an important role.  In such settings, researchers need to ensure that the stakeholders’ rights and integrity are respected. This paper identifies and discusses some of the ethical challenges and issues a researcher can face, using an example case. Focusing on user feedback, this case can serve as an example for CrowdRE, i.e. several of our findings might apply to CrowdRE in general. However, further research is needed as our work mainly reflects the challenges experienced by the authors of this paper.

  • Honfi, Daniel
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Williams Portal, Natalie
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Leander, John
    KTH Royal Institute of Technology, Sweden.
    Larsson Ivanov, Oskar
    Lund University.
    Björnsson, Ívar
    Lund University, Sweden.
    Plos, Mario
    Chalmers University of Technology; Sweden.
    Zandi, Kamyab
    Chalmers University of Technology, Sweden.
    Carneiro, Erica
    NCC AB, Sweden.
    Lechner, Thomas
    NCC AB; Sweden.
    Magnusson, Jonas
    NCC AB, Sweden.
    Gabrielsson, Henrik
    Tyréns AB, Sweden.
    Inspection and monitoring of bridges in Sweden2018Rapport (Annet vitenskapelig)
    Abstract [en]

    This report provides an overview about recent research activities and current practice concerning inspection and monitoring of the structural performance of bridges and the related decision-making process. A brief review of common methods of collecting information on structural performance of bridges is presented, followed by a description of the use of the information collected in structural analysis and maintenance planning. An overview about the state of the art is given including recent scientific developments. Finally, the current Swedish practice for bridge management is presented.

  • Disputas: 2018-06-11 13:00 2001, Ångströmlaboratoriet, Uppsala
    Engelhardt, Ilka. A. D.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Rymd- och plasmafysik.
    Plasma and Dust around Icy Moon Enceladus and Comet 67P/Churyumov-Gerasimenko2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Saturn's moon Enceladus and comet 67P/Churyumov-Gerasimenko both are examples of icy solar system objects from which gas and dust flow into space. At both bodies, the gas becomes partly ionized and the dust grains get charged. Both bodies have been visited by spacecraft carrying similar Langmuir probe instruments for observing the plasma and the charged dust. As it turns out, the conditions at Enceladus and the comet are different and we emphasize different aspects of their plasma environments. At Enceladus, we concentrate on the characteristic plasma regions and charged dust. At the comet, we investigate the plasma and in particular plasmavariations and cold electrons.

    At Enceladus, internal frictional heating leads to gas escaping from cracks in the ice from the south pole region. This causes a plume of gas, which becomes partially ionized, and dust, becoming charged. We have investigated the plasma and charged nanodust in this region by the use of the Langmuir probe (LP) of the Radio and Plasma Wave Science (RPWS) instrument on Cassini. The dust charge density can be calculated from the quasineutrality condition, the difference between ion and electron density measurements from LP. We found support for this method by comparing to measurements of larger dust grains by the RPWS electric antennas. We use the LP method to find that the plasma and dust environment of Enceladus can be divided into at least three regions. In addition to the well known plume, these are the plume edge and the trail region.

    At the comet, heat from the Sun sublimates ice to gas dragging dust along as it flows out into space. When the neutral gas molecules are ionized, by photoionization and electron impact ionization, we get a plasma. Models predict that the electron temperature just after ionization is around 10 eV, but that collisions with the neutral gas should cool the electron gas to below 0.1 eV. We used the Langmuir probe instrument (LAP) on Rosetta to estimate plasma temperatures and show a co-existence of cold and warm electrons in the plasma. We find that the cold plasma often is observed as brief pulses not only in the LAP data but also in the measurements of magnetic field, plasma density and ion energy by other Rosetta plasma instruments. We interpret these pulses as filaments of plasma propagating outwards from a diamagnetic cavity, as predicted by hybrid simulations. The gas production rate of comet 67P varied by more than three orders of magnitude during the Rosetta mission (up to March 2016). We therefore have an excellent opportunity to investigate how the electron cooling in a cometary coma evolves with activity. We used a method combining LAP and the Mutual Impedance Probe (MIP) for deriving the presence of cold electrons. We show that cold electrons were present intermittently during a large part of the mission and as far out as 3 AU. Models suggest only negligible cooling and we suggest that the ambipolar field keeps the electrons close to the nucleus and giving them more time to lose energy by collision.

  • Disputas: 2018-06-08 09:00 Kollegiesalen, Stockholm
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Urbana och regionala studier.
    Producing Publicness: Investigating the Dialectics of Unintended Consequences in Urban Design  - Practices in Stockholm and Malmö2018Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The creation of public space is intended to contribute to the civic infrastructure of a city. The conventional dichotomy of intentions versus outcomes in urban design practice posits that, while intentions represent more abstract thinking about the various facets of publicness, outcomes are the manifest realizations of those intentions in public spaces. This study grounds itself in an exploration of this intention-outcome gap to examine how urban design facilitates the production of publicness, by means of which public spaces can enable appropriations, i.e., the practices of togetherness, encounters, and expressions of different publics. Analysing the appropriations as unintended consequences is about the planning and design process, by which publicness is produced through larger strategies; and, the process of use, by which publicness is socially experienced and contested.

    This research applies a comparative case study approach, as examples of brownfield developments and producing ‘city-like’ (stadsmässighet) urban environments in two practices in Sweden: the Liljeholmstorget Transit Hub in Stockholm and the Western Harbour Waterfront in Malmö. The Liljeholmstorget examines negotiations of land uses and trade-offs with private actors, and its publicness addresses informal togetherness and passive encounters in relation to collective routines of commuting and consumption. The Western Harbour Waterfront reveals a determined process to promote the city’s economic growth and image; planned for the well-being of a specific type of public, which was later contested by unexpected users and their unplanned expressions.

    Comparative analysis demonstrates appropriations as welcome phenomena in urban design because they emphasize the dynamic and contingent characteristics of publicness.

  • Andersson, Petra
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Aras, Silvia
    Lunds University, Sweden.
    Arvidson, Magnus
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Frantzich, Håkan
    Lunds University, Sweden.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Vermina Lundström, Frida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Nilsson, Daniel
    Lunds University, Sweden.
    Runefors, Marcus
    Lunds University, Sweden.
    Riskreducerande åtgärder för dödsbränder i bostäder2018Rapport (Annet vitenskapelig)
    Abstract [en]

    Thisreport summarizes the work conducted within the project ”Analysis of physicaldeterminants and technical measures in support of the zero vision” financed bythe Civil Contingency Authority (MSB) in Sweden. The work aims to find measuresto prevent and reduce the number of fatalities in fires in residentialbuildings in a Sweden, a list of such measures is provided in the end of thereport. The list is based on work conducted in several small sub-projects, ashort summary of these is also provided in the report.

  • Disputas: 2018-06-08 13:15 Entre AIL, Trollhättan
    Högberg, Karin
    Högskolan Väst, Institutionen för ekonomi och it, Avd för företagsekonomi.
    Persistent Digital Service Encounters: Challenges of organizational use of social media in a hotel chain2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The emergence of social media has in many ways changed how individuals interact, communicate and also consume online. Due to the massive, world wide use of social media, organizations are starting to use social media in order to be present where their customers are. Earlier research has studied social media from different, rather fragmented perspectives such as social media use for marketingor for internal communication. However, research on the organizational implications and challenges from a more general organizational social media use is lacking. This thesis explores organizational implications and challenges of social media use over time. Hence the focus lies on both internal and external organizational activities related to social media use. The consequences of social media have been particularly striking in service industries, e.g. banks, restaurants and travel agencies. Social media has fundamentally changed how we (can) buy services, and also how service is provided. For example, we can ask a question or make a complaint directly on a specific social media platform. Hence, social media have had implications for the relationship between service organizations and their customers and thus changed the context in which service is delivered and experienced. The service encounter, i.e., the actual meeting between the customer and employees, has come to take place on social media platforms. The expansion of social media has affected the hotel industry in several ways. Hotel guests are using social media platforms in order to review and share experiences about hotels, and hotel organizations use social media to keep up with competitors and customer demands. The aim of this thesis is to describe and understand the challenges social media use brings to organizations in the service industry, inparticular hotel organizations. The following research question is addressed:Why and how does the use of social media platforms represent organizational challenges? The empirical data focuses on the introduction and use of social media in one international hotel chain over a four-year period. Furthermore, data was collected from other, independent hotels. The empirical data was collected through interviews, online observations, workplace observations and written documents. VIIIA multifaceted theoretical framework was used, including the Technology-Organization-Environment framework, the concept of technological frames, andthe concepts of functional simplification and closure. These theoretical frameworks capture the drivers behind organizational social media use and how individual employees interpret and use social media, but also how social media attributes create the need for new organizational routines and management of social media content created outside organizational boundaries.The analysis illustrates how social media use creates challenges for the studied organizations. Five main organizational challenges have been identified: the nature of social media versus organizational structure: how organizations and individuals make sense of social media over time; how private use of social mediahas implications for professional use; how social media creates stretched service encounters; and pseudo-relationships and roboticization of service

  • Disputas: 2018-06-12 14:00 Magnélisalen, Kemiska övningslaboratoriet, Stockholm
    Kaduk, Mateusz
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
    Functional Inference from Orthology and Domain Architecture2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Proteins are the basic building blocks of all living organisms. They play a central role in determining the structure of living beings and are required for essential chemical reactions. One of the main challenges in bioinformatics is to characterize the function of all proteins. The problem of understanding protein function can be approached by understanding their evolutionary history. Orthology analysis plays an important role in studying the evolutionary relation of proteins. Proteins are termed orthologs if they derive from a single gene in the species' last common ancestor, i.e. if they were separated by a speciation event. Orthologs are useful because they retain their function more often than other homologs. 

    Inference of a complete set of orthologs for many species is computationally intensive. Currently, the fastest algorithms rely on graph-based approaches, which compare all-vs-all sequences and then cluster top hits into groups of orthologs. The initial step of performing all-vs-all comparisons is usually the primary computational challenge as it scales quadratically with the number of species. 

    A new, more scalable and less computationally demanding method was developed to solve this problem without sacrificing accuracy. The Hieranoid 2 algorithm reduces computational complexity to almost linear by overcoming the necessity to perform all-vs-all similarity searches. The algorithm progresses along a known species tree, from leaves to root. Starting at the leaves, ortholog groups are predicted conventionally and then summarized at internal nodes to form pseudo-species. These pseudo-species are then re-used to search against other (pseudo-)species higher in the tree. This way the algorithm aggregates new ortholog groups hierarchically. The hierarchy is a natural structure to store and view large multi-species ortholog groups, and provides a complete picture of inferred evolutionary events. 

    To facilitate explorative analysis of hierarchical groups of orthologs, a new online tool was created. The HieranoiDB website provides precomputed hierarchical groups of orthologs for a set of 66 species. It allows the user to search for orthology assignments using protein description, protein sequence, or species. Evolutionary events and meta information is added to the hierarchical groups of orthologs, which are shown graphically as interactive trees. This representation allows exploring, searching, and easier visual inspection of multi-species ortholog groups.

    The majority of orthology prediction methods focus on treating the whole protein sequence as a single evolutionary unit. However, proteins are often composed of individual units, called protein domains, that can have different evolutionary histories. To extend the full sequence based methodology to a domain-aware method, a new approach called Domainoid is proposed. Here, domains are extracted from full-length sequences and subjected to orthology inference. This allows Domainoid to find orthology that would be missed by a full sequence approach.

    Networks are a convenient graphical representation for showing a large number of functional associations between genes or proteins. They allow various analyses of graph properties, and can help visualize complex relationships. A framework for inferring comprehensive functional association networks was developed, called FunCoup. A major difference compared to other networks is FunCoup's extensive use of orthology relationships between species, which significantly boosts its coverage. Using naïve Bayesian classifiers to integrate 10 different evidence types and orthology transfer, FunCoup captures functional associations of many types, and provides comprehensive networks for 17 species across five gold-standards.

  • Disputas: 2018-06-12 10:00 Nordenskiöldsalen, Geovetenskapens hus, Stockholm
    Gewert, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Chemical Pollutants Released to the Marine Environment by Degradation of Plastic Debris2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Since the beginning of the mass production in the 1940s, plastic has been manufactured in quickly increasing amounts. Plastic debris accumulates in the environment and lately much attention has been drawn to the pollution in the world’s oceans. Despite the rapid development and ubiquitous presence of plastic, degradation in the marine environment and potential risks associated with plastic are not fully understood. Thus, these knowledge gaps were addressed in this thesis, which adds information about exposure and hazards of marine plastic debris.

    Although sampling studies have been conducted all over the world, the concentrations of plastic debris in the Baltic Sea have hardly been investigated. In Paper I, the level and distribution of plastic debris in the Stockholm Archipelago were assessed. Plastic concentrations were higher close to suspected point sources compared to remote areas. Fibers accounted for the most common form and the predominant polymer types were polypropylene (PP) and polyethylene (PE).

    In Paper II, the literature was critically reviewed for the most important degradation pathways for plastic under environmentally relevant conditions. Ultraviolet (UV) radiation, leading to photo-oxidation, is the most important initiating factor for buoyant plastic. Consequently, a UV lamp was used in Paper III for an artificial weathering setup in the laboratory to degrade pristine plastics and analyze the chemical leachates by liquid chromatography-mass spectrometry (LC-MS) for degradation products using a nontarget approach. Carboxylic acids and dicarboxylic acids of polymer fragments were the most commonly identified degradation products of the plastic polymers, confirming predictions made in Paper II.

    To evaluate potential hazards posed by leachates from weathering plastic debris to marine organisms, an acute toxicity screening study with Nitocra spinipes was conducted in Paper IV. Field-exposed plastic and the corresponding newly purchased plastic were artificially aged with the same weathering setup as in Paper III. Poly(vinyl chloride) (PVC) and PP leachates were generally most toxic, while leachates from polystyrene (PS) and poly(ethylene terephthalate) (PET) were least toxic among the tested materials. For plastics, which were supposed to contain only few additives, we observed no difference in toxicity between leachates from the field-exposed and the newly purchased plastic. However, the other plastic products exposed to the marine environment were more toxic than their corresponding newly bought products. This indicates that the toxicity of the leachates not only depends on the polymer type, but also on the weathering condition of the plastic.

  • Disputas: 2018-06-12 13:00 FB53, Stockholm
    Khan, Shehryar
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Combined Quantum Mechanical and Molecular Dynamics study of paramagnetic complexes: Towards an understanding of electronic spin relaxation2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The prime objectives of contrast agents in Magnetic Resonance Imaging (MRI) is to accelerate the relaxation rate of the solvent water protons in the surrounding tissue. Paramagnetic relaxation originates from dipole-dipole interactions between the nuclear spins and the fluctuating magnetic field induced by unpaired electrons. Currently Gadolinium(III) chelates are the most widely used contrast agents in MRI, and therefore it is incumbent to extend the fundamental theoretical understanding of parameters that drive the relaxation mechanism in these complexes. In compounds such as Gadolinium(III) complexes with total electron spins higher than 1 (in this case S=7/2) the Zero-Field Splitting (ZFS) plays a significant role in influencing the electron spin dynamics and nuclear spin dynamics. For this purpose, the current research delves into an understanding of the relaxation process, focusing on ZFS in various complexes of interest, using multi-scale modelling by combining quantum, semi-quantum and newtonian methods.

    We compare and contrast Density Function Theory (DFT) with multi-configurational quantum chemical calculation and find that DFT is highly functional dependent and unreliable in accurately reproducing experimental data for the static ZFS. It was found that long-range corrected functionals (in particular LC-BLYP) perform significantly better as compared to other functionals in predicting the magnitude of the static ZFS. We study hydrated Gd(III) and Eu(II) systems to compare and contrast these isoelectronic complexes (both contain 7 unpaired electrons in their valence shell) and through ab-initio molecular dynamics (AIMD) sampling followed by multi-reference quantum chemical calculations, it was established that inclusion of the first shell has a dominant influence (over 90%) on the ZFS. We also studied the complex [Gd(III)(HPDO3A)(H2O)], which is of clinical relevance as a contrast agent for MRI, through post-Hartree-Fock and DFT calculations by utilizing configurations derived from AIMD trajectories. From the fluctuations in the ZFS tensor, we extract a correlation time of the transient ZFS which is on the sub-picosecond time scale, showing a faster decay than experimental data.

  • Disputas: 2018-05-24 13:15 Nobel (BL32), B-huset, ingång 23, Linköping
    Mwakisisile, Andongwisye John
    Linköpings universitet, Matematiska institutionen, Optimeringslära. Linköpings universitet, Tekniska fakulteten.
    Asset Liability Management for Tanzania Pension Funds2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents a long-term asset liability management for Tanzania pension funds. As an application, the largest pension fund in Tanzania is considered. This is a pay-as-you-go pension fund where the contributions are used to pay current benefits. The Pension plan analyzed is a final salary defined benefit. Two kinds of pension benefit are considered, a commuted (at retirement) and a monthly (old age) pension. A decision factor in the analysis is the increased life expectancy of the members of the pension fund.

    The presentation is divided into two parts. First is a long-term projection of the fund using a fixed and relatively low return on asset value. Basing on the number of members in 2015, a 50 years projection of members and retirees is done. The corresponding amount of contributions, asset values, benefit payouts, and liabilities are also projected. The evaluation of some possible reforms of the fund is done. Then, the growth of asset values using different asset returns is studied. The projection shows that the fund will not be fully sustainable in a long future due to the increase in life expectancy of its members. The contributions will not cover the benefit payouts and the asset value will not fully cover liabilities. Evaluation of some reforms of the fund shows that they cannot guarantee a long-term sustainability. Higher returns on asset value will improve the asset to liability ratio, but contributions are still insufficient to cover benefit payouts.

    Second is a management based on stochastic programming. This approach allocates investment in assets with the best return to raise the asset value closer to the level of liabilities. The model is based on work by Kouwenberg in 2001 includes some features from Tanzania pension system. In contrast with most asset liability management models for pension funds by stochastic programming, liabilities are modeled by number of years of life expectancy. Scenario trees are generated by using Monte Carlo simulation. Two models according to different investment guidelines are built. First is using the existing investment guidelines and second is using modified guidelines which are practical and suitable for modeling. Numerical results suggest that, in order to improve a long-term sustainability of the Tanzania pension fund system, it is necessary to make reforms concerning the contribution rate, investment guidelines and formulate target levels (funding ratios) to characterize the pension funds’ solvency situation. These reforms will improve the sustainability of the system.

  • Disputas: 2018-06-08 13:00 Sal E2, Stockholm
    Wennman, Aron
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    Random and optimal configurations in complex function theory2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis consists of six articles spanning over several areas of mathematical analysis. The dominant theme is the study of random point processes and optimal point configurations, which may be though of as systems of charged particles with mutual repulsion. We are predominantly occupied with questions of universality, a phenomenon that appears in the study of random complex systems where seemingly unrelated microscopic laws produce systems with striking similarities in various scaling limits. In particular, we obtain a complete asymptotic expansion of planar orthogonal polynomials with respect to exponentially varying weights, which yields universality for the microscopic boundary behavior in the random normal matrix (RNM) model (Paper A) as well as in the case of more general interfaces for Bergman kernels (Paper B). Still in the setting of RNM ensembles, we investigate properties of scaling limits near singular points of the boundary of the spectrum, including cusps points (Paper C). We also obtain a central limit theorem for fluctuations of linear statistics in the polyanalytic Ginibre ensemble, using a new representation of the polyanalytic correlation kernel in terms of algebraic differential operators acting on the classical Ginibre kernel (Paper D). Paper E is concerned with an extremal problem for analytic polynomials, which may heuristically be interpreted as an optimal packing problem for the corresponding zeros. The last article (Paper F) concerns a different theme, namely a sharp topological transition in an Lp-analogue of classical Carleman classes for 0 < p < 1.

  • Disputas: 2018-05-31 10:00 Q2, Stockholm
    Josilo, Sladana
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Decentralized Algorithms for Resource Allocation in Mobile Cloud Computing Systems2018Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The rapid increase in the number of mobile devices has been followed by an increase in the capabilities of mobile devices, such as the computational power, memory and battery capacity. Yet, the computational resources of individual mobile devices are still insufficient for various delay sensitive and computationally intensive applications. These emerging applications could be supported by mobile cloud computing, which allows using external computational resources. Mobile cloud computing does not only improve the users’ perceived performance of mobile applications, but it also may reduce the energy consumption of mobile devices, and thus it may extend their battery life. However, the overall performance of mobile cloud computing systems is determined by the efficiency of allocating communication and computational resources. The work in this thesis proposes decentralized algorithms for allocating these two resources in mobile cloud computing systems. In the first part of the thesis, we consider the resource allocation problem in a mobile cloud computing system that allows mobile users to use cloud computational resources and the resources of each other. We consider that each mobile device aims at minimizing its perceived response time, and we develop a game theoretical model of the problem. Based on the game theoretical model, we propose an efficient decentralized algorithm that relies on average system parameters, and we show that the proposed algorithm could be a promising solution for coordinating multiple mobile devices. In the second part of the thesis, we consider the resource allocation problem in a mobile cloud computing system that consists of multiple wireless links and a cloud server. We model the problem as a strategic game, in which each mobile device aims at minimizing a combination of its response time and energy consumption for performing the computation. We prove the existence of equilibrium allocations of mobile cloud resources, and we use game theoretical tools for designing polynomial time decentralized algorithms with a bounded approximation ratio. We then consider the problem of allocating communication and computational resources over time slots, and we show that equilibrium allocations still exist. Furthermore, we analyze the structure of equilibrium allocations, and we show that the proposed decentralized algorithm for computing equilibria achieves good system performance. By providing constructive equilibrium existence proofs, the results in this thesis provide low complexity decentralized algorithms for allocating mobile cloud resources for various mobile cloud computing architectures.

  • Disputas: 2018-06-15 10:00 E2, Stockholm
    Bessman, Alexander
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Interactions between battery and power electronics in an electric vehicle drivetrain2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The electric machine and power electronics in electric and hybrid electric vehicles inevitably cause AC harmonics on the vehicle's DC-link. These harmonics can be partially filtered out by large capacitors, which today are overdimensioned in order to protect the vehicle's battery pack. This is done as a precaution, since it is not known whether ripple-current has any harmful effect on Li-ion  cells.

    We have measured and analyzed the ripple-current present in a hybrid electric bus, and found that a majority of the power was carried by frequencies in the range 100~Hz to 1~kHz. The single most energetic harmonic in this particular vehicle is believed to have been caused  by a misaligned resolver in the motor.

    We have also designed and built an advanced experimental set-up in order to study the effect of ripple-current on Li-ion cells in the lab. The set-up can cycle up to 16 cells simultaneously, with currents of up to 50~A including a superimposed AC signal with a frequency of up to 2~kHz. The cells' temperatures are controlled by means of a climate chamber. The set-up also includes a sophisticated safety system which automatically acts to prevent dangerous situations before they arise.

    Using this set-up we tested whether superimposing AC with a specific frequency improves the charging performance of Li-ion cells. Statistical analysis found no improvement over regular DC cycling, and a physics-based model explains the experimental findings.

    We have also investigated whether ripple-current accelerates the aging of Li-ion cells. Twelve cells were either calendar or cycle  aged for one year, with some cells being exposed to superimposed AC with a frequency of 1~Hz, 100~Hz, or 1~kHz. No effect was observed on any of capacity fade, power fade, or aging mechanism.

    Finally we also tested whether it is possible to heat Li-ion cells from low temperatures using only AC. We propose a method for AC heating of Li-ion cells, and open the discussion for generalizing the technique to larger battery packs.

    In conclusion, ripple-current has negligible effect on Li-ion cells, except for heating them slightly.

  • Disputas: 2018-06-08 13:00 Sal N420, Umeå
    Bohlin, Ludvig
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Toward higher-order network models2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Complex systems play an essential role in our daily lives. These systems consist of many connected components that interact with each other. Consider, for example, society with billions of collaborating individuals, the stock market with numerous buyers and sellers that trade equities, or communication infrastructures with billions of phones, computers and satellites.

    The key to understanding complex systems is to understand the interaction patterns between their components - their networks. To create the network, we need data from the system and a model that organizes the given data in a network representation. Today's increasing availability of data and improved computational capacity for analyzing networks have created great opportunities for the network approach to further prosper. However, increasingly rich data also gives rise to new challenges that question the effectiveness of the conventional approach to modeling data as a network. In this thesis, we explore those challenges and provide methods for simplifying and highlighting important interaction patterns in network models that make use of richer data.

    Using data from real-world complex systems, we first show that conventional network modeling can provide valuable insights about the function of the underlying system. To explore the impact of using richer data in the network representation, we then expand the analysis for higher-order models of networks and show why we need to go beyond conventional models when there is data that allows us to do so. In addition, we also present a new framework for higher-order network modeling and analysis. We find that network models that capture richer data can provide more accurate representations of many real-world complex systems.

  • Disputas: 2018-06-07 14:00 Kollegiesalen, Stockholm
    Ghaem Sigarchian, Sara
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Small-Scale Decentralized Energy Systems: optimization and performance analysis2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Small-scale polygeneration energy systems, providing multiple energy services, such as heating, electricity, cooling, and clean water, using multiple energy sources (renewable and non-renewable) are considered an important component in the energy transition movement. Exploiting locally available energy sources and providing energy services close to the end users have potential environmental, economic, and societal benefits. Furthermore, integration of thermal and electro-chemical storages in the system can decrease fossil fuel consumption, particularly when applying a long-term perspective.

    Despite their promising potential, the global share of power generation by these systems, including the combined heat and power (CHP) systems, is relatively low in the current energy market. To investigate the applicability of these systems, their competitiveness in comparison with conventional energy solutions should be carefully analyzed in terms of energy, economy, and the environment. However, determining whether the implementation of a polygeneration system fulfills economic, energetic, and environmental criteria is a challenging process. Additionally, the design of such systems is a complex task, due to a system design with various generation and storage modules, and the continuous interaction between the modules, load demand fluctuations, and the intermittent nature of renewable energy sources.

    In this research study, a method to identify the optimal size for small-scale polygeneration systems and suitable operating strategies is proposed. Based on this method, a mathematical model is developed that can optimize the design in terms of energy, economy, and the environment relative to a reference system for a given application. Moreover, the developed model is used to investigate the effects of various parameters on the performance of the system, including, among others, the selected operating strategy and load characteristics as well the climate zones through a number of case studies. It is concluded that the application of a small-scale polygeneration energy system potentially has considerable energetic and environmental benefits. However, its economic feasibility varies from case to case. The concluding remarks are primarily intended to provide a general perception of the potential application of a polygeneration system as an alternative solution. It also provides a general understanding of the effects of various parameters on the design and performance of a complex polygeneration system.

    The results from various case studies demonstrate that the developed model can efficiently identify the optimal size of a polygeneration system and its performance relative to a reference system. This can support engineers and researchers as well as investors and other decision makers to realize whether a polygeneration system is a good choice for a specific case.

  • Disputas: 2018-06-08 09:00 N320, Naturvetarhuset, Umeå
    Lindfors, Maria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för naturvetenskapernas och matematikens didaktik.
    "Kunskap är vad du vet, och vet du inte kan du alltid googla!": elevers epistemic beliefs i naturvetenskaplig undervisningskontext2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    One important goal of science education is to help students develop an adequate understanding of what science is and how it is done. An understanding of science includes epistemic beliefs, that is, individuals’ beliefs about the nature of knowledge, how knowledge is constructed, and how knowledge can be justified. The epistemic beliefs are hypothesized to exist on a continuum ranging from naïve to sophisticated. Students’ epistemic beliefs and their epistemic cognition have been shown to influence various facets of learning. The overarching purpose of this thesis is to contribute to our knowledge and understanding of the role played by epistemic beliefs within the context of science education. The thesis intended to answer the following three general questions within a scientific context: 1) What prerequisites for drawing conclusions about epistemic beliefs are given based on the choice of questionnaire as a measurement method, including its design and content? 2) What is the relation between students’ epistemic beliefs and other phenomena that are important in learning situations? 3) What is the relation between students’ epistemic beliefs and their epistemic practices?

    The studies used both quantitative and qualitative methods to examine students’ epistemic beliefs and epistemic practices. Data sources included questionnaires, video and screen observations, and semi-structured interviews. Participants in the studies were students in Grade 5-11 in Sweden and Germany. A series of four papers address the purpose of the thesis and respond to the three general questions. The first paper investigate relations between students’ epistemic beliefs and perceived classroom characteristics and whether differences could be found between the two countries. The second paper investigate the relative importance of epistemic beliefs dimensions for predicting achievement goals in Grade 5 through 11, in both a cross-sectional and a longitudinal study. The third paper explore the relationships between students’ scientific epistemic beliefs, their problemsolving process, and the quality of solutions produced by students. Finally, the fourth paper describe students’ epistemic practices of problem solving in science and their sense making in the moment, to deepen the understanding of the process of the students’ epistemic cognition. In relation to the first question, results indicate that the chosen measurement method for epistemic beliefs generates certain prerequisites for how epistemic beliefs can be understood and characterized. This in turn may have consequences when epistemic beliefs are studied in relation to, for example, other phenomena and epistemic practices. With regard to the second question, findings show that there are many relationships between epistemic beliefs and other phenomena, but also that they are in many cases context and/or situation dependent. Regarding the third question, the results point out that the relationship between students’ epistemic beliefs and their epistemic practices should be understood by how the students show, through words and actions, that they understand what the situation requires. Thus, there is no universal relationship between sophisticated epistemic beliefs and successful epistemic practices. It can be concluded that students’ epistemic beliefs do not exist in a vacuum without interacting with other phenomena, but that they depend on the surrounding context or situation in different ways. More studies that take into account different types of situations are required. This would in turn most likely also contribute to a better understanding of how students’ epistemic beliefs, epistemic cognition, and epistemic practices develop in relation to the surrounding teaching context.

  • Disputas: 2018-06-08 10:15 S213H, Umeå
    Nilsson Blom, Marcus
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för socialt arbete.
    Opioidberoende: en studie om beroendevården och det sociala sammanhangets betydelse2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Opioid dependence is highly associated with health problems relating to physical health (infectious diseases) as well as mental health (depression, anxiety, antisocial behavior). In addition, research has found an association between use of opioids and increased risk of premature death as a consequence of overdose or other circumstances, such as suicide. Furthermore, opioid dependent individuals experience a high level of social exclusion and problems with relationships, housing, income and livelihood. Overall, there is a connection between opioid dependence and physical, psychological and social vulnerability as well as premature death.

    The importance of social cohesion has rarely been the focus in research on opioid dependence. Therefore, there is a need to further explore whether differences in outcomes (medication assisted treatment, mortality and co-morbidity) in addition to individual characteristics, can be derived from social aspects of the opioid dependent individual’s life.

    The overall aim of the dissertation is to examine individual and social factors among individuals who are dependent on opioids and how they are associated with outcomes relating to: a) medication assisted treatment; and b) mortality and co-morbidity.

    This dissertation is based on data from four different registers. The first and second sub-studies use ASI data. The third uses DOK data from the National Board of Institutions (SiS) and the Death Registry (National Board of Health and Welfare). The fourth study is based on both DOKdata and data from the national patient registry (National Board of Health and Welfare).

    Overall, this dissertation confirms the understanding of opioid dependence as associated with a high level of vulnerability. This dissertation shows that opioid dependence is characterized by extensive care efforts, low levels of employment, and a high level of mental health and comorbidity.

    This dissertation shows that the characteristics related to the social network (parenting, work and education) are of significance for being in treatment, but also remaining in care (medication assisted treatment), which in turn promotes the individual's health and long-term health development. In that, this dissertation shows that for individuals dependent on opioids, there is an association between being part of a social network and favorable health development.

  • Disputas: 2018-06-08 09:00 Aulan, Vårdvetarhuset, Umeå
    Molin, Jenny
    Umeå universitet, Medicinska fakulteten, Institutionen för omvårdnad.
    Time Together: a nursing intervention targeting everyday life in psychiatric inpatient care : patient and staff perspectives2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Background: Patient and staff descriptions of everyday life in psychiatric inpatient care are consistent, revealing a challenging environment with over-reliance on medication and, power imbalances. Patients and staff ask for the opportunity to develop relationships; however, the literature on nursing interventions targeting these issues is sparse. This thesis comprises four studies with a twofold overall aim. The first part constructs a theoretical understanding of everyday life processes in psychiatric inpatient care, and the second part evaluates a nursing intervention in psychiatric inpatient care.

    Methods: Studies I and II used a grounded theory design with individual interviews (I, II), dyadic interviews (II) and focus group discussions (II). Study III used mixed methods, a single system experimental design with questionnaires and a qualitative process evalu­ation with logs and participant observations. Study IV used a qualitative design with individual semi structured interviews. The participants were 16 patients with experiences of psychiatric inpatient care (I), 36 staff members who worked in psychiatric inpatient care (II), 80 patients and 50 staff members in the evaluated wards (III) and 11 patients who had taken part in the nursing intervention Time Together (IV). In studies I and II the analysis followed grounded theory. In study III data were subjected to visual analysis, per­centage of non-overlapping data and qualitative content analysis, also used in study IV.

    Results: Patients in psychiatric inpatient care experienced everyday life as being influenced by interactions between patients and staff, the environment and the content of care. The quality of interactions was what tied these components together. Having trustful interactions could compensate for an otherwise poor environment and a confusing care content, while adapting to absence of, or obstructive interactions contributed to experiences of the environment as stigmatizing and the care content as confusing (I). Staff had ideals regarding everyday life on the wards but obstacles hindered them from putting their ideals into practice. To cope with this, they appeared to shift their focus from the patient’s best to their own survival. This resignation made it even more difficult for them to work in a way that aligned with their ideals (II). The theoretical understanding that was constructed from study I and II revealed that what patients described as absent or obstructive interactions, or passivity, were mirrored by staff descriptions of obstacles in their everyday life on the wards. Furthermore, what patients described as trustful inter­actions and satisfying activities were mirrored by staff descriptions of having the patients’ best interest at heart. This is interpreted as when staff is able to focus on the patients’ best interests, improvements in the everyday life in psychiatric inpatient care are possible.

    The nursing intervention called Time Together was feasible to introduce in psychiatric inpatient care. The intervention was enabled by shared responsibility, a friendly approach and a predictable structure, whilst it was hindered by a distant approach and unpredictable structure. Measurements showed no effect on the quality of interactions between patients and staff, but questionable effects on perceived stress and stress of conscience among staff, as well as on staff satisfaction with interactions with patients (III). Patients described their experiences of taking part in the intervention as being seen as a human among other humans, that it contributed to hope for recovery but also, that feelings of distance to staff were fostered when Time Together sessions were not offered (IV).

    Conclusion: By implementing Time Together in psychiatric inpatient care, staff is allowed access to a nursing intervention that can meet patients’ needs for high-quality interactions in everyday life and that may have potential to decrease perceived stress and stress of conscience among staff and increase their satisfaction with interactions with patients. By using joint activities as bridging actions, this intervention could lead to the development of nurse-patient relationships built on reciprocity and engagement, something that is emphasised in recovery-oriented mental health nursing.

  • Disputas: 2018-06-08 13:00 MA121, Umeå
    Bayisa, Fekadu Lemessa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Statistical methods in medical image estimation and sparse signal recovery2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis presents work on methods for the estimation of computed tomography (CT) images from magnetic resonance (MR) images for a number of diagnostic and therapeutic workflows. The study also demonstrates sparse signal recovery method, which is an intermediate method for magnetic resonance image reconstruction. The thesis consists of four articles. The first three articles are concerned with developing statistical methods for the estimation of CT images from MR images. We formulated spatial and non-spatial models for CT image estimation from MR images, where the spatial models include hidden Markov model (HMM) and hidden Markov random field model (HMRF) while the non-spatial models incorporate Gaussian mixture model (GMM) and skewed-Gaussian mixture model (SGMM). The statistical models are estimated via a maximum likelihood approach using the EM-algorithm in GMM and SGMM, the EM gradient algorithm in HMRF and the Baum–Welch algorithm in HMM. We have also examined CT image estimation using GMM and supervised statistical learning methods. The performance of the models is evaluated using cross-validation on real data. Comparing CT image estimation performance of the models, we have observed that GMM combined with supervised statistical learning method has the best performance, especially on bone tissues. The fourth article deals with a sparse modeling in signal recovery. Using spike and slab priors on the signal, we formulated a sparse signal recovery problem and developed an adaptive algorithm for sparse signal recovery. The developed algorithm has better performance than the recent iterative convex refinement (ICR) algorithm. The methods introduced in this work are contributions to the lattice process and signal processing literature. The results are an input for the research on replacing CT images by synthetic or pseudo-CT images, and for an efficient way of recovering sparse signal.

  • Disputas: 2018-06-08 13:00 Karl Kempe Salen, Umeå
    Pourbozorgi Langroudi, Parham
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Insights into the roles of the essential Pfh1 DNA helicase in the nuclear and mitochondrial genomes2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Eukaryotic cells have two sets of genomes, the nuclear and mitochondrial, and both need to be accurately maintained. Also, the rate of transcription must be precisely regulated in these genomes. However, there are many natural barriers that dysregulate these processes. The aim of this thesis was to enhance our understanding of the Schizosaccharomyces pombe, Pif1 family helicase, Pfh1, and its roles in the nuclear and mitochondrial genomes. The S. pombe genome contains 446 predicted Gquadruplex (G4) structures. By circular dichroism and Thioflavin-T assay we demonstrated that sequences from the ribosomal DNA (rDNA) and telomeres form G4 structures in vitro. The recombinant nuclear isoform of Pfh1 bound and unwound these G4 structures. Also, by chromatin immunoprecipitation combined with quantitative PCR (ChIP-qPCR), we showed that Pfh1 binds these sequences in vivo. This work provides evidence that G4 structure formation in the rDNA and telomere regions is biologically important and that unwinding of G4 structures is a conserved property of Pif1 family helicases. Using ChIP-seq we found that Pfh1 binds to natural fork barriers, such as highly transcribed genes, and nucleosome depleted regions, and that replication through these sites were dependent on Pfh1. By immunoaffinity precipitation combined with mass spectrometry, Pfh1 interacted with several replisome components, as well as DNA repair proteins, and mitochondrial proteins. Furthermore, Pfh1 moved with similar kinetics as the leading strand polymerase. These findings suggest that Pfh1 is needed at natural fork barriers to promote fork progression, and that it is not just recruited to its target sites but moves with the replisome. Based on these findings, we anticipated that lack of Pfh1 would affect expression of highly transcribed genes. By performing genome-wide transcriptome analysis of S. pombe in the absence of Pfh1, we showed that highly transcribed genes are downregulated more often than other genes. Furthermore, combining absence of Pfh1 together with Topoisomerase 1 (Top1), resulted in slower cell growth, reduced DNA synthesis rate compared to single mutants, and upregulation of genes associated with DNA repair and apoptosis. These data suggest that, cells lacking both Pfh1 and Top1 have severe problem in maintaining their genomes. By ChIP-qPCR analysis we showed that Pfh1 and Top1 directly bind to mitochondrial DNA. In addition, these cells upregulated many metabolic pathways and lost about 80% of their mtDNA. These data suggest that both Pfh1 and Top1 are required for maintenance of mtDNA. This is the first evidence showing that Top1 is present in S. pombe mitochondria. In conclusion, Pfh1 directly binds mitochondrial DNA, and natural fork barriers in the nuclear DNA, such as G4 structures. In the nucleus, Pfh1 is part of the replisome. Cells lacking Pfh1 and Top1 grow slower, rapidly lose their mitochondrial DNA, have slower nuclear DNA synthesis, and induce apoptotic pathways. Finally, this thesis emphasizes the importance of both Pfh1 and Top1 in maintaining the nuclear and mitochondrial genomes.

  • Hedenmalm, Håkan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    Wennman, Aron
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.).
    A critical topology for L^p Carleman classes with 0<p<12018Inngår i: Mathematische Annalen, ISSN 0025-5831, E-ISSN 1432-1807Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we explore a sharp phase transition phenomenon which occurs for (Formula presented.)-Carleman classes with exponents (Formula presented.). These classes are defined as for the standard Carleman classes, only the (Formula presented.)-bounds are replaced by corresponding (Formula presented.)-bounds. We study the quasinorms (Formula presented.)for some weight sequence (Formula presented.) of positive real numbers, and consider as the corresponding (Formula presented.)-Carleman space the completion of a given collection of smooth test functions. To mirror the classical definition, we add the feature of dilatation invariance as well, and consider a larger soft-topology space, the (Formula presented.)-Carleman class. A particular degenerate instance is when (Formula presented.) for (Formula presented.) and (Formula presented.) for (Formula presented.). This would give the (Formula presented.)-Sobolev spaces, which were analyzed by Peetre, following an initial insight by Douady. Peetre found that these (Formula presented.)-Sobolev spaces are highly degenerate for (Formula presented.). Indeed, the canonical map (Formula presented.) fails to be injective, and there is even an isomorphism (Formula presented.)corresponding to the canonical map (Formula presented.) acting on the test functions. This means that e.g. the function and its derivative lose contact with each other (they “disconnect”). Here, we analyze this degeneracy for the more general (Formula presented.)-Carleman classes defined by a weight sequence (Formula presented.). If (Formula presented.) has some regularity properties, and if the given collection of test functions is what we call (Formula presented.)-tame, then we find that there is a sharp boundary, defined in terms of the weight (Formula presented.): on the one side, we get Douady–Peetre’s phenomenon of “disconnexion”, while on the other, the completion of the test functions consists of (Formula presented.)-smooth functions and the canonical map (Formula presented.) is correspondingly well-behaved in the completion. We also look at the more standard second phase transition, between non-quasianalyticity and quasianalyticity, in the (Formula presented.) setting, with (Formula presented.).

  • Josilo, Sladana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Dán, György
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Decentralized Algorithm for Randomized Task Allocation in Fog Computing SystemsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Fog computing is identified as a key enablerfor using various emerging applications by battery poweredand computationally constrained devices. In this paper, weconsider devices that aim at improving their performanceby choosing to offload their computational tasks to nearbydevices or to a cloud server. We develop a game theoreticalmodel of the problem, and we use variational inequalitytheory to compute an equilibrium task allocation in staticmixed strategies. Based on the computed equilibrium strategy,we develop a decentralized algorithm for allocating thecomputational tasks among nearby devices and the cloudserver. We use extensive simulations to provide insight intothe performance of the proposed algorithm, and we compareits performance with the performance of a myopic bestresponse algorithm that requires global knowledge of thesystem state. Despite the fact that the proposed algorithmrelies on average system parameters only, our results showthat it provides good system performance close to that of themyopic best response algorithm.

  • Josilo, Sladana
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Dán, György
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Decentralized Scheduling for Offloading of Periodic Tasks in Mobile Edge Computing2018Inngår i: IFIP NETWORKING 2018, 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Motivated by various surveillance applications, we consider wireless devices that periodically generate computationally intensive tasks. The devices aim at maximizing their performance by choosing when to perform the computations and whether or not to offload their computations to a cloud resource via one of multiple wireless access points. We propose a game theoretic model of the problem, give insight into the structure of equilibrium allocations and provide an efficient algorithm for computing pure strategy Nash equilibria. Extensive simulation results show that the performance in equilibrium is significantly better than in a system without coordination of the timing of the tasks’ execution, and the proposed algorithm has an average computational complexity that is linear in the number of devices.