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  • Public defence: 2017-05-26 10:00 Häggsalen, Uppsala
    Winding, Jacob
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Localization, supersymmetric gauge theories and toric geometry2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Gauge theories is one of the most pervasive and important subject of modern theoretical physics, and there are still many things about them we do not understand. In particular dealing with strongly coupled theories where normal perturbative techniques do not apply is a fundamental open problem. In this thesis, we study a particular class of toy-models that have supersymmetry, which makes them much easier to deal with. We employ the mathematical technique of localization, which for supersymmetric theories lets us evaluate certain path integrals exactly and for any value of the coupling. This is used to study the 5d N=1 theories placed on toric Sasaki-Einstein manifolds and compute their partition functions, finding that they factorize into a product of contributions from each closed Reeb orbit of the manifold. This computation leads us to define two new hierarchies of special functions associated to these manifolds, and we study their properties. Finally, we use the 5d N=1 theories to construct new 4d N=2 theories on a large class of curved backgrounds. These theories have some interesting features, such as supporting both instantons and anti-instantons, and having a position-dependent complexified coupling constant.

    List of papers
    1. Gluing Nekrasov partition functions
    Open this publication in new window or tab >>Gluing Nekrasov partition functions
    2015 (English)In: Communications in Mathematical Physics, ISSN 0010-3616, E-ISSN 1432-0916, Vol. 337, no 2, 785-816 p.Article in journal (Refereed) Published
    Abstract [en]

    In this paper we summarise the localisation calculation of 5D superYang-Mills on simply connected toric Sasaki-Einstein (SE) manifolds. We showhow various aspects of the computation, including the equivariant index, theasymptotic behaviour and the factorisation property are governed by thecombinatorial data of the toric geometry. We prove that the full perturbativepartition function on a simply connected SE manifold corresponding to an n-gontoric diagram factorises to n copies of perturbative Nekrasov partitionfunction. This leads us to conjecture the full partition function as gluing ncopies of full Nekrasov partition function. This work is a generalisation ofsome earlier computation carried out on $Y^{p,q}$ manifolds, whose moment mapcone has a quadrangle and our result is valid for manifolds whose moment mapcones have pentagon base, hexagon base, etc. The algorithm we used for dealingwith general cones may also be of independent interest.

    National Category
    Subatomic Physics
    Research subject
    Theoretical Physics
    Identifiers
    urn:nbn:se:uu:diva-252090 (URN)10.1007/s00220-015-2351-7 (DOI)000353505300008 ()
    Note

    Preprint number:  UUITP-02/14

    Available from: 2015-04-29 Created: 2015-04-29 Last updated: 2017-04-03Bibliographically approved
    2. Modular properties of full 5D SYM partition function
    Open this publication in new window or tab >>Modular properties of full 5D SYM partition function
    2016 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 16, no 03, 193Article in journal (Refereed) Published
    Abstract [en]

    We study properties of the full partition function for the U(1) 5D N=2∗ gauge theory with adjoint hypermultiplet of mass M. This theory is ultimately related to abelian 6D (2,0) theory. We construct the full non-perturbative partition function on toric Sasaki-Einstein manifolds by gluing flat copies of the Nekrasov partition function and we express the full partition function in terms of the generalized double elliptic gamma function GC2 associated with a certain moment map cone C. The answer exhibits a curious SL(4,ℤ) modular property. Finally, we propose a set of rules to construct the partition function that resembles the calculation of 5D supersymmetric partition function with the insertion of defects of various co-dimensions.

    National Category
    Subatomic Physics
    Research subject
    Theoretical Physics
    Identifiers
    urn:nbn:se:uu:diva-287828 (URN)10.1007/JHEP03(2016)193 (DOI)000373391900002 ()
    Funder
    Swedish Research Council, 2014-5517The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Knut and Alice Wallenberg Foundation
    Available from: 2016-04-26 Created: 2016-04-26 Last updated: 2017-04-03Bibliographically approved
    3. Multiple elliptic gamma functions associated to cones
    Open this publication in new window or tab >>Multiple elliptic gamma functions associated to cones
    (English)Manuscript (preprint) (Other academic)
    National Category
    Mathematical Analysis
    Research subject
    Mathematics
    Identifiers
    urn:nbn:se:uu:diva-318666 (URN)
    Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2017-04-03
    4. N=2 supersymmetric gauge theory on connected sums of S2xS2
    Open this publication in new window or tab >>N=2 supersymmetric gauge theory on connected sums of S2xS2
    2017 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 03, 026Article in journal (Refereed) Published
    Abstract [en]

    We construct 4D N = 2 theories on an infinite family of 4D toric manifolds with the topology of connected sums of S-2 x S-2. These theories are constructed through the dimensional reduction along a non -trivial U(1) -fiber of 5D theories on toric Sasaki Einstein manifolds. We discuss the conditions under which such reductions can be carried out and give a partial classification result of the resulting 4D manifolds. We calculate the partition functions of these 4D theories and they involve both instanton and anti-instanton contributions, thus generalizing Pestun's famous result on S-4.

    National Category
    Subatomic Physics
    Research subject
    Theoretical Physics
    Identifiers
    urn:nbn:se:uu:diva-318662 (URN)10.1007/JHEP03(2017)026 (DOI)000397669900008 ()
    Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2017-04-19Bibliographically approved
  • Public defence: 2017-05-26 13:15 Geijersalen, Uppsala
    Båth, Katarina
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Literature.
    Ironins skiftningar — jagets förvandlingar: Om romantisk ironi och subjektets paradox i texter av P. D. A. Atterbom2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation explores the intimate relationship between irony and romantic subjectivity, by drawing on feminist psychoanalytical theory, via an examination of the shiftings of irony, and humor, in the works of the Swedish romanticist P. D. A. Atterbom (1790–1855). It looks at the critical role played by irony in the formation of Romantic subjectivity, and explores irony’s potential to undermine dualistically gendered notions of subject-object relations. For Atterbom, irony is an aesthetic concept closely related to drama, informed not only by German Romantic-ironic theorists such as Friedrich Schlegel and Jean Paul, but also by the works of Shakespeare, Ludwig Tieck, and E. T. A. Hoffmann.

    The thesis follows the shiftings of Romantic irony in Atterbom’s major literary texts: the cycle of poems Blommorna [The Flowers] (1811), where the Ovidian transformations are used metafictively to play with the relation between poet, poem, and reader; and the literary satire Rimmarbandet [The Rhyme Band] (1810), which, inspired by Tieck’s Der Gestiefelte Kater (1797), uses the metafictive theatre-in-the-theatre motif, as well as carnivalesque and grotesque motifs to expose contrived theatricality and homosocial misogyny in the prevailing culture. The dynamic between the satirist’s subject and the attacked object is a polarized power struggle, where revolt is followed by submission. In this respect, Romantic satire is here conservative. In the fairy tale play Lycksalighetens ö [Island of Felicity] (1824–27), tragedy’s irony is a dialectic between the ideal and the real that strives to create both inner and outer renewal. The play reaches out metafictively to the reader and turns her/him into the poet of a new version of the fairy tale. The reading/writing process inscribed in the work thus becomes a form of renewal and liberation from grief, and old, patriarchal gender roles. Finally, the humorous, unfinished idyll Fågel Blå [Blue Bird] (1814, 1818, 1858) is a work in many pieces, a fragment, a sketch and a non finito that together stages a restorative creative process, where the reader is asked to take part in joining together the scattered parts of Blue Bird itself.

    To conclude, irony is a feature of Romanticism, which makes the Romantic, literary subject relational and dialogical, open to its Other, and herein lies a form of ethics and an escape from a conventional, patriarchal notion of the self. I discuss this with Julia Kristeva’s theories on how subjectivity changes when it becomes poetic and Jessica Benjamin’s Winnicott-influenced theory of how play can offer a way out from patriarchy’s strict gender roles. The shiftings of irony in Atterbom’s work show a development from the satirical subject, where an aggressive form of self-assertion conceals a lack of individuality – via tragedy’s painstaking efforts to integrate repressed aspects of the self – to the idyll’s more harmonious subject, who has the capacity to laugh at him/herself and see both the grotesque in the holy, and the holy in the grotesque.

  • Public defence: 2017-05-27 09:15 Enghoffsalen, Uppsala
    Sima, Eduardo
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences.
    Gastric bypass: Technical aspects and long-term results2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Roux-en-Y gastric bypass (RYGBP) achieves superior short- and long-term weight loss compared to other weight loss modalities. Different operative techniques have been developed to technically facilitate the surgical procedure, with consequences in the form of an array of postoperative complications and gastrointestinal symptoms. Furthermore, as our follow-up on operated patients extends beyond the first postoperative years, it becomes apparent that a significant number of patients experience unsatisfactory weight result. Current research is just starting to chart factors associated with postoperative long-term weight regain with the ultimate goal of preventing it.

    In Paper I it is found that the linear stapled technique for the gastrojejunostomy in laparoscopic RYGBP is associated with shorter operative time, in-hospital stay and a lower incidence of surgical site infections and anastomotic strictures compared to the circular stapled technique. Paper II demonstrates that, despite no differences in weight result, the 21-mm circular stapled technique for the gastrojejunostomy is associated with a higher incidence of vomiting and endoscopic anastomotic dilatations compared to the 25-mm circular stapled technique and the linear stapled technique in the long-term after RYGBP. Paper III shows that despite differences in body composition, long-term weight responders and non-responders after RYGBP did not differ in resting, glucose-induced or activity-related energy expenditure. Lastly Paper IV shows long-term weight result is associated with fasting levels of leptin and ghrelin, and that the response of these hormones to a glucose load might contribute to perpetuate obesity.

    List of papers
    1. Differences in Early Complications between Circular and Linear Stapled Gastrojejunostomy in Laparoscopic Gastric Bypass
    Open this publication in new window or tab >>Differences in Early Complications between Circular and Linear Stapled Gastrojejunostomy in Laparoscopic Gastric Bypass
    2014 (English)In: Obesity Surgery, ISSN 0960-8923, E-ISSN 1708-0428, no 4, 599-603 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND

    Laparoscopic gastric bypass (LGBP) is the most common bariatric procedure worldwide. The gastrojejunostomy can be stapled with a circular or linear stapler, each with their own specific advantages. We have evaluated differences in postoperative complications between the two techniques.

    METHODS

    We studied operative data and postoperative complications in 560 patients (79.8 % females, median age 42, BMI 42.5) operated with LGBP between 2008 and 2012 at our center. The gastrojejunostomy was initially performed using a circular stapler (CS) in 288 patients and later by linear stapler (LS) in 272. Complications, operative time, and length of stay were retrieved from our database. The risk of developing a port site infection was evaluated with multivariate logistic regression.

    RESULTS

    Port site infections were more common with CS than LS, 5.2 and 0.4 %, respectively (p < 0.01). Multivariate analysis demonstrated CS to be an independent risk factor for port site infections (OR 16.3 (2.09-126), p < 0.01), as well as for stomal ulcers (OR 10.1, 1.15-89, p = 0.04). Major postoperative complications remained unchanged (anastomotic leak 1.0 vs. 1.1 %, abscess 0.7 vs. 0.4 %), while operative time and length of stay were found to be shorter using the LS (122 vs. 83 min, p < 0.001 and 4 vs. 3 days, p < 0.001).

    CONCLUSIONS

    The linear stapled technique yielded lower incidence of port site infections, probably by avoiding the passage of a contaminated circular stapler through the abdominal wall. No difference in major complications was seen, but operative time was shorter using a linear stapler instead of a circular stapler.

    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-216391 (URN)10.1007/s11695-013-1139-0 (DOI)000334174500015 ()24323525 (PubMedID)
    Available from: 2014-01-21 Created: 2014-01-21 Last updated: 2017-04-05Bibliographically approved
    2. Gastrointestinal symptoms, weight loss and patient satisfaction 5 years after gastric bypass: a study of three techniques for the gastrojejunal anastomosis.
    Open this publication in new window or tab >>Gastrointestinal symptoms, weight loss and patient satisfaction 5 years after gastric bypass: a study of three techniques for the gastrojejunal anastomosis.
    2016 (English)In: Surgical Endoscopy, ISSN 0930-2794, E-ISSN 1432-2218, Vol. 30, no 4, 1553-1558 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: The optimal operative technique in gastric bypass (RYGB) is still under debate. We have studied patient-reported gastrointestinal symptoms and weight loss 5 years after RYGB performed with three different stapling techniques for the gastrojejunal anastomosis (GJ).

    METHODS: Out of 593 patients operated with RYGB, 489 patients [80.2 % women, body mass index (BMI) 44.9 (33-68) kg/m(2)] answered our 5-year follow-up questionnaire concerning gastrointestinal symptoms (vomiting, reflux, dumping, abdominal pain or diarrhea), weight loss, need for postoperative endoscopic interventions and overall satisfaction with the procedure. We compared the results for three different GJ techniques: linear stapler (LS, n = 103), 21-mm circular stapler (C21, n = 88) and 25-mm circular stapler (C25, n = 298).

    RESULTS: Dumping was the most commonly reported symptom (14.1 % of all patients on a weekly to daily basis), however, less frequently reported in the C25 group (p < 0.05). Vomiting, prevalent in 2.9 % of all patients, was more frequently reported in the C21 group (p < 0.01). No group consistently showed greater weight loss compared to the other two groups. A higher incidence of endoscopic dilatations due to strictures was reported in the C21 group (12.5 % compared to 4.5 % of all patients, p < 0.05). Overall patient satisfaction was high (88 %).

    CONCLUSION: Our data suggest that the technique for the construction of the GJ in RYGB affects gastrointestinal symptoms 5 years postoperatively. The difference is moderate but indicates that a narrow GJ results in increased frequency of vomiting and need for endoscopic interventions without improving the weight result.

    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-290410 (URN)10.1007/s00464-015-4374-8 (DOI)000373022200042 ()26162421 (PubMedID)
    Available from: 2016-04-29 Created: 2016-04-29 Last updated: 2017-04-05Bibliographically approved
    3. Non-responders after gastric bypass surgery for morbid obesity: long-term weight result and energy expenditure
    Open this publication in new window or tab >>Non-responders after gastric bypass surgery for morbid obesity: long-term weight result and energy expenditure
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keyword
    gastric bypass; REE; energy expenditure; RQ; insulin resistance; weight loss; long-term results
    National Category
    Surgery
    Research subject
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-319509 (URN)
    Available from: 2017-04-05 Created: 2017-04-05 Last updated: 2017-04-05
    4. Non-responders after gastric bypass surgery for morbid obesity: Hormone response and glucose homeostasis during an oral glucose tolerance test
    Open this publication in new window or tab >>Non-responders after gastric bypass surgery for morbid obesity: Hormone response and glucose homeostasis during an oral glucose tolerance test
    (English)Manuscript (preprint) (Other academic)
    Keyword
    gastric bypass; incretins; leptin; weight loss; long-term results
    National Category
    Surgery
    Research subject
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-319508 (URN)
    Available from: 2017-04-05 Created: 2017-04-05 Last updated: 2017-04-05
  • Public defence: 2017-05-31 09:15 Häggsalen, Uppsala
    Carpman, Nicole
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity. Uppsala University.
    Resource characterization and variability studies for marine current power2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Producing electricity from marine renewable resources is a research area that develops continuously. The field of tidal energy is on the edge to progress from the prototype stage to the commercial stage. However, tidal resource characterization, and the effect of tidal turbines on the flow, is still an ongoing research area in which this thesis aims to contribute.

    In this thesis, measurements of flow velocities have been performed at three kinds of sites. Firstly, a tidal site has been investigated for its resource potential in a fjord in Norway. Measurements have been performed with an acoustic Doppler current profiler to map the spatial and temporal characteristics of the flow. Results show that currents are in the order of 2 m/s in the center of the channel. Furthermore, the flow is highly bi-directional between ebb and flood flows. The site thus has potential for in-stream energy conversion. Secondly, a river site serves as an experimental site for a marine current energy converter that has been designed at Uppsala University and deployed in Dalälven, Söderfors. The flow rate at the site is regulated by an upstream hydro power plant, making the site suitable for experiments on the performance of the vertical axis turbine in a natural environment. The turbine was run in steady discharge flows and measurements were performed to characterize the extent of the wake. Lastly, at an ocean current site, the effect that transiting ferries may have on submerged devices was investigated. Measurements were conducted with two sonar systems to obtain an underwater view of the wake caused by a propeller and a water jet thruster respectively.

    Furthermore, the variability of the intermittent renewable sources wind, solar, wave and tidal energy was investigated for the Nordic countries. All of the sources have distinctly different variability features, which is advantageous when combining power generated from them and introducing it on the electricity grid. Tidal variability is mainly due to four aspects: the tidal regime, the tidal cycle, local bathymetry causing turbulence, asymmetries etc. and weather effects. Models of power output from the four sources was set up and combined in different energy mixes for a “highly renewable” and a “fully renewable” scenario. By separating the resulting power time series into different frequency bands (long-, mid-, mid/short-, and short-term components) it was possible to minimize the variability on different time scales. It was concluded that a wise combination of intermittent renewable sources may lower the variability on short and long time scales, but increase the variability on mid and mid/short time scales.

    The tidal power variability in Norway was then investigated separately. The predictability of tidal currents has great advantages when planning electricity availability from tidal farms. However, the continuously varying tide from maximum power output to minimum output several times per day increases the demand for backup power or storage. The phase shift between tidal sites introduces a smoothing effect on hourly basis but the tidal cycle, with spring and neap tide simultaneously in large areas, will inevitably affect the power availability.

    List of papers
    1. Measurements of tidal current velocities in the Folda fjord, Norway, with the use of a vessel mounted ADCP
    Open this publication in new window or tab >>Measurements of tidal current velocities in the Folda fjord, Norway, with the use of a vessel mounted ADCP
    2014 (English)In: 33Rd International Conference On Ocean, Offshore And Arctic Engineering, 2014, Vol 8A: Ocean Engineering, 2014Conference paper, Presentation (Refereed)
    Abstract [en]

    Measurements of tidal current water velocities is an important first step in evaluating the potential for a tidal site to be used as a renewable energy resource. For this reason, on site measurements are performed at the inlet of a fjord situated at the coast of Norway. The site has an average width of 580 m and adepth of 10-15 m which is narrow and shallow enough to give rise to water velocities that can be of use for energy conversion. With the use of an Acoustic Doppler Current Profiler (ADCP) cross-section measurements are conducted along four transects. The measurements covered flood and ebb currents around one tide and the data give a first approximation of the magnitude and distribution of the flow field. Depth averaged mean current velocities are calculated along the transects for horizontal bins with sizes in the order of 50 x 50 m. Maximum mean velocity for the flood currents were 1.31 m/s and 1.46 m/s for the ebb currents. The measurements show that even a small amount of data can give an indication of the potential and characteristics ofthe site.

    Keyword
    Acoustic Doppler Current Profiler (ADCP), tidal energy resource
    National Category
    Marine Engineering Ocean and River Engineering Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-230659 (URN)000363498500053 ()978-0-7918-4550-9 (ISBN)
    Conference
    33rd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2014), San Francisco, California, USA, June 8-13, 2014
    Available from: 2014-08-27 Created: 2014-08-27 Last updated: 2017-04-04Bibliographically approved
    2. Tidal resource characterization in the Folda Fjord, Norway
    Open this publication in new window or tab >>Tidal resource characterization in the Folda Fjord, Norway
    2016 (English)In: International Journal of Marine Energy, ISSN 2214-1669, Vol. 13, 27-44 p.Article in journal (Refereed) Published
    Abstract [en]

    For tidal-stream energy industry to be fully realized, lower velocity sites and fjords should be developed. Finding new prospective sites for in-stream energy extraction from tidal currents is an area of ongoing research. In this paper, the tidal flow at a fjord inlet has been characterized using acoustic Doppler current profiler (ADCP) measurements. This work is based on two survey measurement techniques: transect measurements to map the spatial variability, and seabed measurements to map the temporal variability. The data was analyzed in terms of characterizing metrics, to ensure they are comparable with other resource assessments. Results show that currents exceed 1 m/s for 38% of the time with peak currents of 2.06 m/s at hub height (middle of the water column) and the directional asymmetry is less than 1° between ebb and flood, indicating a truly bi-directional flow. A simple prediction model is proposed which allows peak current speeds to be accurately predicted in the channel center from tidal range data using a linear relationship. The relationship is shown to be strong, with a correlation coefficient of 0.98 at hub height, and a standard variation typically less than 10 cm/s. Furthermore, it is show that a minimum of 9 days of measurements are required to set up the model, although it takes 29 days to reduce the error in peak speed to less than 1%. However, the error is expected to vary depending on where in the monthly tidal cycle the survey begins, it is thus recommended to measure around spring tide if the measurement period is short.

    Keyword
    Tidal resource assessment, ADCP, Characterizing metrics
    National Category
    Engineering and Technology Ocean and River Engineering Oceanography, Hydrology, Water Resources
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-266674 (URN)10.1016/j.ijome.2016.01.001 (DOI)000381687600003 ()
    Funder
    StandUpCarl Tryggers foundation
    Available from: 2015-11-10 Created: 2015-11-10 Last updated: 2017-04-04Bibliographically approved
    3. The Söderfors Project: Experimental Hydrokinetic Power Station Deployment and First Results
    Open this publication in new window or tab >>The Söderfors Project: Experimental Hydrokinetic Power Station Deployment and First Results
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    2013 (English)Conference paper (Refereed)
    Abstract [en]

    The Division of Electricity at Uppsala University recently deployed an experimental hydrokinetic power station for in-stream experiments at a site in a river. This paper briefly describes the deployment process and reports some initial results from measurements made at the test site.

    Keyword
    Marine Current Power, Renewable energy, Söderfors, Strömkraft, Förnybar energi, Söderfors
    National Category
    Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity
    Identifiers
    urn:nbn:se:uu:diva-209220 (URN)
    Conference
    10th European Wave and Tidal Energy Conference (EWTEC), 2-5 september, 2013, Aalborg, Denmark
    Projects
    Marine Current Power
    Funder
    StandUpSwedish Research Council, 621-2009-4946
    Available from: 2013-10-15 Created: 2013-10-15 Last updated: 2017-04-04Bibliographically approved
    4. Studying the Wake of a Marine Current Turbine Using an Acoustic Doppler Current Profiler
    Open this publication in new window or tab >>Studying the Wake of a Marine Current Turbine Using an Acoustic Doppler Current Profiler
    2015 (English)Conference paper (Refereed)
    Abstract [en]

    Wake characteristics of marine current turbines are of significant importance to the development of the marine current power source. Turbine wake recovery determines spacing of turbines in arrays, and environmental impact on e.g. the seabed is heavily influenced by wake behaviour. The majority of previous studies on wakes has been performed on flow-aligned (horizontal) axis turbines and mainly carried out as scale model experiments or numerical simulations.

    This paper describes the performance of wake measurements at the Söderfors test site, where an experimental marine current power station is operated in a river. The turbine is of the cross-flow (vertical) axis type, and the measurements are performed using an Acoustic Doppler Current Profiler (ADCP) towed on the surface by a boat. Positioning data is taken from a high-accuracy Global Navigation Satellite System. The paper discusses various aspects of the methodology employed and provides examples of taken measurements.

    National Category
    Energy Engineering Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-265358 (URN)
    Conference
    11th European Wave and Tidal Energy Conference, EWTEC15, 6-11 September 2015, Nantes, France
    Available from: 2015-10-27 Created: 2015-10-27 Last updated: 2017-04-04Bibliographically approved
    5. Observation of cavitating flow using multibeam and dual-beam sonar systems: A comparison of wake strength caused by propeller vs waterjet thrusted vessels. In a marine renewable energy perspective (Part-a)
    Open this publication in new window or tab >>Observation of cavitating flow using multibeam and dual-beam sonar systems: A comparison of wake strength caused by propeller vs waterjet thrusted vessels. In a marine renewable energy perspective (Part-a)
    (English)In: Article in journal (Refereed) Submitted
    Abstract
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-307239 (URN)
    Available from: 2016-11-11 Created: 2016-11-11 Last updated: 2017-04-04
    6. Variability Assessment and Forecasting of Renewables: A Review for Solar, Wind, Wave and Tidal Resources
    Open this publication in new window or tab >>Variability Assessment and Forecasting of Renewables: A Review for Solar, Wind, Wave and Tidal Resources
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    2015 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 44, 356-375 p.Article in journal (Refereed) Published
    National Category
    Energy Engineering Engineering and Technology
    Research subject
    Engineering Science with specialization in Science of Electricity; Engineering Science with specialization in Solid State Physics
    Identifiers
    urn:nbn:se:uu:diva-225870 (URN)10.1016/j.rser.2014.12.019 (DOI)000351324300025 ()
    Available from: 2014-06-09 Created: 2014-06-09 Last updated: 2017-04-04
    7. Net load variability in Nordic countries with a highly or fully renewable power system
    Open this publication in new window or tab >>Net load variability in Nordic countries with a highly or fully renewable power system
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    2016 (English)In: Nature Energy, ISSN 2058-7546, Vol. 1, 1-8 p., 16175Article in journal (Refereed) Published
    Abstract [en]

    Increasing the share of intermittent renewable energy (IRE) resources such as solar, wind, wave and tidal energy in a power system poses a challenge in terms of increased net load variability. Fully renewable power systems have previously been analysed, but more systematic analyses are needed that explore the effect of different IRE mixes on system-wide variability across different timescales and the optimal combinations of IRE for reducing variability on a given timescale. Here we investigate these questions for the Nordic power system. We show that the optimal mix of IRE is dependent on the frequency band considered. Long-term (>4 months) and short-term (<2 days) fluctuations can be similar to today’s, even for a fully renewable system. However, fluctuations with periods in between will inevitably increase significantly. This study indicates that, from a variability point of view, a fossil- and nuclear-free Nordic power system is feasible if properly balanced by hydropower.

    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-302836 (URN)10.1038/NENERGY.2016.175 (DOI)000394793000001 ()
    Available from: 2016-09-11 Created: 2016-09-11 Last updated: 2017-04-04Bibliographically approved
    8. Tidal current phasing along the coast of Norway
    Open this publication in new window or tab >>Tidal current phasing along the coast of Norway
    2016 (English)Conference paper (Refereed)
    Abstract [en]

    Tidal currents provide an intermittent source of renewable energy. A high degree of intermittency is unfavorable in the existing power system. However, by aggregating tidal power from sites with variable tidal phase a more firm power outpu tmay be achieved. In this paper, the tidal current phasing between 114 potential tidal energy sites along the Norwegian coast is investigated. Time series of tidal currents are generated with a model that considers the variation in current strength due to the variability in the semi-diurnal tidal cycle (spring to neap, flood to ebb, first to second daily tide etc.). From these, available kinetic energy in the natural flow is calculated. A constant conversion rate is then applied to give the power output at each site. Three scenarios, with varying number of sites and energy extraction, are investigated. The variability in each scenario is quantified on different time scales by filtering the aggregated power and calculate standard deviation and step change. It is found that the variability can be lowered by choosing sites with an advantageous time lag and limit the power output from the most energetic sites. As expected, smoothing is most distinct on short time scales.

    Keyword
    Tidal energy, tidal phasing, variability optimization, significant impact factor, model scenarios
    National Category
    Ocean and River Engineering Marine Engineering Oceanography, Hydrology, Water Resources
    Identifiers
    urn:nbn:se:uu:diva-307495 (URN)
    Conference
    3rd International Asian Wave and Tidal Energy Conference (AWTEC), Singapore 24-28 oct, 2016
    Funder
    StandUpÅForsk (Ångpanneföreningen's Foundation for Research and Development), 16-196
    Available from: 2016-12-14 Created: 2016-11-16 Last updated: 2017-04-04
  • Public defence: 2017-06-01 09:15 Lindhalsalen, Uppsala
    Onuț-Brännström, Ioana
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    The puzzle of lichen symbiosis: Pieces from Thamnolia2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Symbiosis brought important evolutionary novelties to life on Earth. Lichens, the symbiotic entities formed by fungi, photosynthetic organisms and bacteria, represent an example of a successful adaptation in surviving hostile environments. Yet many aspects of the lichen symbiosis remain unexplored. This thesis aims at bringing insights into lichen biology and the importance of symbiosis in adaptation. I am using as model system a successful colonizer of tundra and alpine environments, the worm lichens Thamnolia, which seem to only reproduce vegetatively through symbiotic propagules. When the genetic architecture of the mating locus of the symbiotic fungal partner was analyzed with genomic and transcriptomic data, a sexual self-incompatible life style was revealed. However, a screen of the mating types ratios across natural populations detected only one of the mating types, suggesting that Thamnolia has no potential for sexual reproduction because of lack of mating partners. Genetic data based on molecular markers revealed the existence of three morphologically cryptic Thamnolia lineages. One lineage had a clear recombination structure and was found in the tundra region of Siberia, shorelines of Scandinavia, and Aleutian Islands. The other lineage was allopatric with the previous, and was highly clonal; only two haplotypes were found across the alpine region of central and southeastern Europe. However, the third lineage was sympatric with the other two, had a worldwide distribution, and although highly clonal, showed a recombinant population structure. Our data could not reveal whether the signs of recombination resulted from rare recombination events due to the extreme low frequency of the other mating type or ancestral variation before the loss of sexual reproduction. However, investigation of Thamnolia’s green algal population showed that in different localities, different algal genotypes were associated with the same fungal genotype. Furthermore, data suggest that Thamnolia carried several algal genotypes within its thalli and shared them with other distantly related but ecologically similar fungal species.

    List of papers
    1. A worldwide phylogeography of the whiteworm lichens Thamnolia reveals three lineages with distinct habitats and evolutionary histories
    Open this publication in new window or tab >>A worldwide phylogeography of the whiteworm lichens Thamnolia reveals three lineages with distinct habitats and evolutionary histories
    2017 (English)In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    Thamnolia is a lichenized fungus with an extremely wide distribution, being encountered in arctic and alpine environments in most continents. In this study, we used molecular markers to investigate the population structure of the fungal symbiont and the associated photosynthetic partner of Thamnolia. By analyzing molecular, morphological, and chemical variation among 253 specimens covering the species distribution range, we revealed the existence of three mycobiont lineages. One lineage (Lineage A) is confined to the tundra region of Siberia and the Aleutian Islands, a second (Lineage B) is found in the high alpine region of the Alps and the Carpathians Mountains, and a third (Lineage C) has a worldwide distribution and covers both the aforementioned ecosystems. Molecular dating analysis indicated that the split of the three lineages is older than the last glacial maximum, but the distribution ranges and the population genetic analyses suggest an influence of last glacial period on the present-day population structure of each lineage. We found a very low diversity of Lineage B, but a higher and similar one in Lineages A and C. Demographic analyses suggested that Lineage C has its origin in the Northern Hemisphere, possibly Scandinavia, and that it has passed through a bottleneck followed by a recent population expansion. While all three lineages reproduce clonally, recombination tests suggest rare or past recombination in both Lineages A and C. Moreover, our data showed that Lineage C has a comparatively low photobiont specificity, being found associated with four widespread Trebouxia lineages (three of them also shared with other lichens), while Lineages A and B exclusively harbor T. simplex s. lat. Finally, we did not find support for the recognition of taxa in Thamnolia based on either morphological or chemical characters.

    National Category
    Evolutionary Biology Ecology Other Biological Topics
    Identifiers
    urn:nbn:se:uu:diva-319636 (URN)10.1002/ece3.2917 (DOI)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-28Bibliographically approved
    2. Thamnolia tundrae n. sp., a cryptic species and putative glacial relict
    Open this publication in new window or tab >>Thamnolia tundrae n. sp., a cryptic species and putative glacial relict
    (English)Manuscript (preprint) (Other academic)
    National Category
    Biological Systematics
    Identifiers
    urn:nbn:se:uu:diva-319635 (URN)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-18
    3. Differential sharing of photobionts in sympatric populations of Thamnolia and Cetraria lichens: evidence from next generation sequencing
    Open this publication in new window or tab >>Differential sharing of photobionts in sympatric populations of Thamnolia and Cetraria lichens: evidence from next generation sequencing
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Ecology Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319634 (URN)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-18
    4. Constraints to sex by a single mating type? Genomic and population analyses reveal insight into the reproductive biology of Thamnolia
    Open this publication in new window or tab >>Constraints to sex by a single mating type? Genomic and population analyses reveal insight into the reproductive biology of Thamnolia
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319638 (URN)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-18
  • Public defence: 2017-06-01 09:15 Häggsalen, Uppsala
    Böhme, Solveig
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fundamental Insights into the Electrochemistry of Tin Oxide in Lithium-Ion Batteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis aims to provide insight into the fundamental electrochemical processes taking place when cycling SnO2 in lithium-ion batteries (LIBs). Special attention was paid to the partial reversibility of the tin oxide conversion reaction and how to enhance its reversibility. Another main effort was to pinpoint which limitations play a role in tin based electrodes besides the well-known volume change effect in order to develop new strategies for their improvement. In this aspect, Li+ mass transport within the electrode particles and the large first cycle charge transfer resistance were studied. Li+ diffusion was proven to be an important issue regarding the electrochemical cycling of SnO2. It was also shown that it is the Li+ transport inside the SnO2 particles which represents the largest limitation. In addition, the overlap between the potential regions of the tin oxide conversion and the alloying reaction was investigated with photoelectron spectroscopy (PES) to better understand if and how the reactions influence each other`s reversibility.

    The fundamental insights described above were subsequently used to develop strategies for the improvement of the performance and the cycle life for SnO2 electrodes in LIBs. For instance, elevated temperature cycling at 60 oC was employed to alleviate the Li+ diffusion limitation effects and, thus, significantly improved capacities could be obtained. Furthermore, an ionic liquid electrolyte was tested as an alternative electrolyte to cycle at higher temperatures than 60 oC which is the thermal stability limit for the conventional LP40 electrolyte. In addition, cycled SnO2 nanoparticles were characterized with transmission electron microscopy (TEM) to determine the effects of long term high temperature cycling. Also, the effect of vinylene carbonate (VC) as an electrolyte additive on the cycling behavior of SnO2 nanoparticles was studied in an effort to improve the capacity retention. In this context, a recently introduced intermittent current interruption (ICI) technique was employed to measure and compare the development of internal cell resistances with and without VC additive.

    List of papers
    1. On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries
    Open this publication in new window or tab >>On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries
    2015 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, 482-494 p.Article in journal (Refereed) Published
    Abstract [en]

    As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO2 coated tin electrodes can be described based on the SnO2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO2 is caused by the reformed SnO2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO2 capacity could, however, be obtained by cycling to 3.5 V vs. Li+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF2 at potentials larger than 2.8 V vs. Li+/Li is due to the fact that SnF2 is formed below the SnO2 layer. This improved electrochemical understanding of the SnO2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.

    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-262075 (URN)10.1016/j.electacta.2015.02.150 (DOI)000362292200059 ()
    Funder
    Swedish Foundation for Strategic Research
    Available from: 2015-09-08 Created: 2015-09-08 Last updated: 2017-04-04Bibliographically approved
    2. Overlapping and Rate Controlling Electrochemical Reactions for Tin(IV) Oxide Electrodes in Lithium-Ion Batteries
    Open this publication in new window or tab >>Overlapping and Rate Controlling Electrochemical Reactions for Tin(IV) Oxide Electrodes in Lithium-Ion Batteries
    (English)Article in journal (Other academic) Submitted
    Keyword
    Tin oxide, Lithium-ion batteries, Electrochemistry, Cyclic Voltammetry, Mass transport
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-319389 (URN)
    Available from: 2017-04-04 Created: 2017-04-04 Last updated: 2017-04-04
    3. Elevated Temperature Lithium-Ion Batteries Containing SnO2 Electrodes and LiTFSI-Pip14TFSI Ionic Liquid Electrolyte
    Open this publication in new window or tab >>Elevated Temperature Lithium-Ion Batteries Containing SnO2 Electrodes and LiTFSI-Pip14TFSI Ionic Liquid Electrolyte
    Show others...
    2017 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, A701-A708 p.Article in journal (Refereed) Published
    Abstract [en]

    The performance of lithium-ion batteries (LIBs) comprising SnO2 electrodes and an ionic liquid (IL) based electrolyte, i.e., 0.5 MLiTFSI in Pip14TFSI, has been studied at room temperature (i.e., 22◦C) and 80◦C. While the high viscosity and low conductivity ofthe electrolyte resulted in high overpotentials and low capacities at room temperature, the SnO2 performance at 80◦C was found to beanalogous to that seen at room temperature using a standard LP40 electrolyte (i.e., 1MLiPF6 dissolved in 1:1 ethylene carbonate anddiethyl carbonate). Significant reduction of the IL was, however, found at 80◦C, which resulted in low coulombic efficiencies duringthe first 20 cycles, most likely due to a growing SEI layer and the formation of soluble IL reduction products. X-ray photoelectronspectroscopy studies of the cycled SnO2 electrodes indicated the presence of an at least 10 nm thick solid electrolyte interphase (SEI)layer composed of inorganic components such as lithium fluoride, sulfates, and nitrides as well as organic species containing C-H,C-F and C-N bonds.

    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-316877 (URN)10.1149/2.0861704jes (DOI)
    Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2017-04-18Bibliographically approved
    4. Photoelectron Spectroscopic Evidence for Overlapping Redox Reactions for SnO2 Electrodes in Lithium-Ion Batteries
    Open this publication in new window or tab >>Photoelectron Spectroscopic Evidence for Overlapping Redox Reactions for SnO2 Electrodes in Lithium-Ion Batteries
    2017 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 9, 4924-4936 p.Article in journal (Refereed) Published
    Abstract [en]

    In-house and synchrotron-based photoelectron spectroscopy (XPSand HAXPES) evidence is presented for an overlap between the conversion andalloying reaction during the cycling of SnO2 electrodes in lithium-ion batteries(LIBs). This overlap resulted in an incomplete initial reduction of the SnO2 as wellas the inability to regenerate the reduced SnO2 on the subsequent oxidative scan.The XPS and HAXPES results clearly show that the SnO2 conversion reactionoverlaps with the formation of the lithium tin alloy and that the conversion reactiongives rise to the formation of a passivating Sn layer on the SnO2 particles. The latterlayer renders the conversion reaction incomplete and enables lithium tin alloy toform on the surface of the particles still containing a core of SnO2. The results alsoshow that the reoxidation of the lithium tin alloy is incomplete when the formationof tin oxide starts. It is proposed that the rates of the electrochemical reactions andhence the capacity of SnO2-based electrodes are limited by the lithium masstransport rate through the formed layers of the reduction and oxidations products.In addition, it is shown that a solid electrolyte interphase (SEI) layer is continuously formed at potentials lower than about 1.2 VLi+/Li during the first scan and that a part of the SEI dissolves on the subsequent oxidative scan. While the SEI was found tocontain both organic and inorganic species, the former were mainly located at the SEI surface while the inorganic species werefound deeper within the SEI. The results also indicate that the SEI dissolution process predominantly involves the organic SEIcomponents.

    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-316876 (URN)10.1021/acs.jpcc.7b01529 (DOI)000396295800017 ()
    Funder
    Swedish Foundation for Strategic Research StandUp
    Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2017-04-18Bibliographically approved
    5. The Influence of Al2O3 and Diamond as Additives on the Performance of SnO2 Electrodes in Lithium-Ion Batteries
    Open this publication in new window or tab >>The Influence of Al2O3 and Diamond as Additives on the Performance of SnO2 Electrodes in Lithium-Ion Batteries
    (English)Manuscript (preprint) (Other academic)
    Keyword
    Tin oxide, Lithium-ion batteries, Electrochemistry, Mass transport, SEM
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-319391 (URN)
    Available from: 2017-04-04 Created: 2017-04-04 Last updated: 2017-04-18
    6. Effects of Elevated Temperature and Vinylene Carbonate Additive on the Electrochemical Performance of SnO2 Nanoparticles in Lithium-Ion Batteries
    Open this publication in new window or tab >>Effects of Elevated Temperature and Vinylene Carbonate Additive on the Electrochemical Performance of SnO2 Nanoparticles in Lithium-Ion Batteries
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keyword
    Tin oxide, Lithium-ion batteries, High temperature cycling, Electrolyte additive, Electrochemistry, Resistance
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-319393 (URN)
    Available from: 2017-04-04 Created: 2017-04-04 Last updated: 2017-04-18
  • Public defence: 2017-06-01 09:15 Polhemsalen, Uppsala
    Verma, Vasudha
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Development of a Neutron Flux Monitoring System for Sodium-cooled Fast Reactors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Safety and reliability are one of the key objectives for future Generation IV nuclear energy systems. The neutron flux monitoring system forms an integral part of the safety design of a nuclear reactor and must be able to detect any irregularities during all states of reactor operation. The work in this thesis mainly concerns the detection of in-core perturbations arising from unwanted movements of control rods with in-vessel neutron detectors in a sodium-cooled fast reactor. Feasibility study of self-powered neutron detectors (SPNDs) with platinum emitters as in-core power profile monitors for SFRs at full power is performed. The study shows that an SPND with a platinum emitter generates a prompt current signal induced by neutrons and gammas of the order of 600 nA/m, which is large enough to be measurable. Therefore, it is possible for the SPND to follow local power fluctuations at full power operation. Ex-core and in-core detector locations are investigated with two types of detectors, fission chambers and self-powered neutron detectors (SPNDs) respectively, to study the possibility of detection of the spatial changes in the power profile during two different transient conditions, i.e. inadvertent withdrawal of control rods (IRW) and one stuck rod during reactor shutdown (OSR). It is shown that it is possible to detect the two simulated transients with this set of ex-core and in-core detectors before any melting of the fuel takes place. The detector signal can tolerate a noise level up to 5% during an IRW and up to 1% during an OSR.

    List of papers
    1. Neutron flux monitoring with in-vessel fission chambers to detect an inadvertent control rod withdrawal in a sodium-cooled fast reactor
    Open this publication in new window or tab >>Neutron flux monitoring with in-vessel fission chambers to detect an inadvertent control rod withdrawal in a sodium-cooled fast reactor
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    2016 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 94, 487-493 p.Article in journal (Refereed) Published
    Abstract [en]

    The neutron flux monitoring system forms an integral part of the safety design of a Generation IV sodium-cooled fast reactor. During the initial design phase of the neutron flux monitoring system, one needs to explore various detector locations and configurations. Diverse possibilities of the detector system installation should be studied for different locations in the reactor vessel in order to detect any perturbations in the core. In this paper, we investigate the possibility of placing fission chambers beyond the lateral neutron shield, ex-core but in-vessel and study the detectability of an inadvertent control rod withdrawal with these fission chambers. A generic core design of a Generation IV 1500 MWth French sodium-cooled fast reactor is used for the study, and calculations are performed with the Monte Carlo code SERPENT2. We propose certain design changes that are needed to be incorporated, w.r.t. the facilitation of neutron transport to this ex-core location.

    We are able to show that there is a detectable signature in the fission chambers following an inadvertent control rod withdrawal in the core. The equally-spaced azimuthal detectors are able to follow changes in the neutron flux distribution in the core. This study helps us to analyze multiple detector locations and give the general trends for monitoring indications to detect any perturbations in the core.

    Keyword
    Protection systems; Safety; Accidents; Instrumentation; Sodium cooled fast reactors; Fission chambers
    National Category
    Subatomic Physics
    Research subject
    Physics with specialization in Applied Nuclear Physics
    Identifiers
    urn:nbn:se:uu:diva-297046 (URN)10.1016/j.anucene.2016.04.019 (DOI)000377231600054 ()
    Funder
    Swedish Research Council, B0774801
    Available from: 2016-06-21 Created: 2016-06-21 Last updated: 2017-04-11Bibliographically approved
    2. CALCULATION METHODOLOGY ASSESSMENT TO DETECT LOCALISED PERTURBATION IN SODIUM-COOLED FAST REACTOR WITH EX-CORE INSTRUMENTATION
    Open this publication in new window or tab >>CALCULATION METHODOLOGY ASSESSMENT TO DETECT LOCALISED PERTURBATION IN SODIUM-COOLED FAST REACTOR WITH EX-CORE INSTRUMENTATION
    2016 (English)In: CALCULATION METHODOLOGY ASSESSMENT TO DETECTLOCALISED PERTURBATION IN SODIUM-COOLED FAST REACTORWITH EX-CORE INSTRUMENTATION, 2016Conference paper (Refereed)
    Abstract [en]

    Safety and reliability are essential requirements for development and operation of SodiumcooledFast Reactors. Development of a neutron flux monitoring system (NFMS) for the FrenchSFR is one of the key R&D areas identified. Diverse possibilities of detector system installationshould be studied for different locations in the reactor vessel in order to detect any perturbations inthe core. In this paper, we aim to explore two calculation routes available for neutron flux monitoring,assess them for their efficiency to detect fission rate variation at Above-core structure (ACS)location and discuss the associated pros and cons. The two calculational approaches we refer hereare criticality mode and external source mode. We discuss the feasibility of choosing this locationfor detecting in-core perturbations and evaluate the methodology needed to achieve it. The paperfocuses on the difficulties associated with neutron detection when the detectors are located at far-offdistances from the source. We found that for a difficult case such as ours where the detectors arelocated far-away from the source, criticality mode doesn’t work. Variance reduction techniques,employed in the external source mode are indispensable to drive neutrons to areas of interest.

    Keyword
    Sodium Cooled Fast reactors, Fission chambers, Instrumentation, Variance reduction
    National Category
    Subatomic Physics
    Research subject
    Physics with specialization in Applied Nuclear Physics
    Identifiers
    urn:nbn:se:uu:diva-297045 (URN)
    Conference
    PHYSOR 2016
    Funder
    Swedish Research Council, B0774801
    Available from: 2016-06-21 Created: 2016-06-21 Last updated: 2017-05-09
    3. Progress in the development of the neutron fluxmonitoring system of the French GEN-IV SFR:simulations and experimental validations
    Open this publication in new window or tab >>Progress in the development of the neutron fluxmonitoring system of the French GEN-IV SFR:simulations and experimental validations
    2015 (English)Conference paper (Other academic)
    Abstract [en]

    The neutron flux monitoring system of the FrenchGEN-IV sodium-cooled fast reactor will rely on hightemperaturefission chambers installed in the reactor vessel andcapable of operating over a wide-range neutron flux. Thedefinition of such a system is presented and the technologicalsolutions are justified with the use of simulation andexperimental results.

    National Category
    Subatomic Physics
    Research subject
    Physics with specialization in Applied Nuclear Physics
    Identifiers
    urn:nbn:se:uu:diva-269891 (URN)
    Conference
    4th International Conference on Advances in Nuclear Instrumentation Measurement Methods and their Applications (ANIMMA), Lisbon, Portugal, April 20-24, 2015
    Funder
    Swedish Research Council, 349-2011-7748
    Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2017-05-09
    4. Self Powered Neutron Detectors as in-core detectors forSodium-cooled Fast Reactors
    Open this publication in new window or tab >>Self Powered Neutron Detectors as in-core detectors forSodium-cooled Fast Reactors
    Show others...
    (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576Article in journal (Refereed) Submitted
    National Category
    Other Physics Topics
    Identifiers
    urn:nbn:se:uu:diva-314035 (URN)
    Available from: 2017-01-26 Created: 2017-01-26 Last updated: 2017-05-09
    5. Neutron flux monitoring during slow transient conditions in a Sodium-cooled fast reactor.
    Open this publication in new window or tab >>Neutron flux monitoring during slow transient conditions in a Sodium-cooled fast reactor.
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Subatomic Physics
    Identifiers
    urn:nbn:se:uu:diva-319943 (URN)
    Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2017-05-09
  • Public defence: 2017-06-01 13:00 Auditorium Minus, Uppsala
    Brantnell, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    Exploitation of University-Based Healthcare Innovations: The Behaviors of Three Key Actors and Influencing Factors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Large resources are invested in healthcare research, but despite this there is a wide gap between research knowledge and healthcare practice. Implementation researchers have addressed this gap, focusing mostly on the role of healthcare practitioners. However, a narrow focus on implementation does not take into consideration the preceding stages and the roles of different actors during the whole innovation process, which starts from research and ends with implementation. The aim of this thesis is to examine the behaviors of three key actors during an innovation process and to explore the influence of selected contextual factors on their behavior.

    Study I (n=10 funders) identifies several facilitative roles for funders and suggests that implementation risks becoming no one’s responsibility as the funders identify six different actors responsible for implementation, the majority of whom embody a collective or an organization. Study II finds that the implementation knowledge of Swedish funding managers (n=18) is mostly based on experience-based knowledge. The majority of the funding managers define implementation as a process and express limited knowledge of implementation. The findings of Study III (n=4 innovation cases) show that the roles and involvement of academic inventors and ISAs (innovation-supporting actors) are more connected to intellectual property (IP) nature than to intellectual property rights (IPR) ownership. Study IV (n=4 innovation cases) identifies three different logics that influence the behavior of academic inventors: market, academic and care logics. A pattern emerges where the behavior of academic inventors is guided by a unique logic and there is no interaction between logics, despite the existence of multiple logics. The individual strategies to handle multiple logics coincide with the influence of logics. In addition, IP nature, distinguishing between high-tech and low-tech innovations, is connected to the influence of institutional logics: low-tech connected to the care logic and high-tech connected to the market logic.

    This thesis has three main theoretical and practical implications relevant for practitioners, policymakers and researchers. First, implementation responsibility is an important issue to study and discuss, because without clearly defined responsibilities and management of responsibilities, responsibility might become no one’s responsibility. Second, the finding that experience-based implementation knowledge contributes heavily to policymakers’ knowledge encourages further studies and discussions regarding this relatively neglected issue. Third, the importance of IP nature in shaping innovation processes should be considered and further examined, not only as a factor influencing inventors and ISAs’ roles and involvement, but also as influencing the prevalence of different institutional logics. Further, the relevance of a distinction between low-tech and high-tech IP should be reflected on.

    List of papers
    1. Research funders’ roles and perceived responsibilities in relation to the implementation of clinical research results: a multiple case study of Swedish research funders
    Open this publication in new window or tab >>Research funders’ roles and perceived responsibilities in relation to the implementation of clinical research results: a multiple case study of Swedish research funders
    2015 (English)In: Implementation Science, ISSN 1748-5908, E-ISSN 1748-5908, Vol. 10, 100Article in journal (Refereed) Published
    Abstract [en]

    Background

    Implementation of clinical research results is challenging, yet the responsibility for implementation is seldom addressed. The process from research to the use of clinical research results in health care can be facilitated by research funders. In this paper, we report the roles of ten Swedish research funders in relation to implementation and their views on responsibilities in implementation.

    Findings

    Ten cases were studied and compared using semi-structured interviews. In addition, websites and key documents were reviewed. Eight facilitative roles for research funders in relation to the implementation of clinical research results were identified. Three of them were common for several funders: “Advocacy work,” “Monitoring implementation outcomes,” and “Dissemination of knowledge.” Moreover, the research funders identified six different actors responsible for implementation, five of which belonged to the healthcare setting. Collective and organizational responsibilities were the most common forms of responsibilities among the identified actors responsible for implementation.

    Conclusions

    The roles commonly identified by the Swedish funders, “Advocacy work,” “Monitoring implementation outcomes,” and “Dissemination of knowledge,” seem feasible facilitative roles in relation to the implementation of clinical research results. However, many actors identified as responsible for implementation together with the fact that collective and organizational responsibilities were the most common forms of responsibilities entail a risk of implementation becoming no one’s responsibility. 

    Keyword
    Quality improvemen, Implementation responsibility, Support of research, Research funder roles
    National Category
    Health Care Service and Management, Health Policy and Services and Health Economy Engineering and Technology
    Research subject
    Health Care Research; Engineering Science with specialization in industrial engineering and management
    Identifiers
    urn:nbn:se:uu:diva-260115 (URN)10.1186/s13012-015-0290-5 (DOI)000358032100002 ()26183210 (PubMedID)
    Projects
    U-CARE
    Funder
    U‐Care: Better Psychosocial Care at Lower Cost? Evidence-based assessment and Psychosocial Care via Internet, a Swedish Example
    Available from: 2015-08-17 Created: 2015-08-17 Last updated: 2017-03-22Bibliographically approved
    2. A Qualitative Exploration of Research Funding Managers’ Implementation Knowledge
    Open this publication in new window or tab >>A Qualitative Exploration of Research Funding Managers’ Implementation Knowledge
    (English)Manuscript (preprint) (Other academic)
    National Category
    Health Care Service and Management, Health Policy and Services and Health Economy
    Identifiers
    urn:nbn:se:uu:diva-317932 (URN)
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-22
    3. The roles and involvement of academic inventors and innovation supporting actors in university-based innovation processes: The influence of IPR ownership and IP nature
    Open this publication in new window or tab >>The roles and involvement of academic inventors and innovation supporting actors in university-based innovation processes: The influence of IPR ownership and IP nature
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-262346 (URN)
    Available from: 2015-09-14 Created: 2015-09-14 Last updated: 2017-03-22
    4. Unique Logics despite Institutional Complexity: An Inductive Study of Academic Inventors and Institutional Logics
    Open this publication in new window or tab >>Unique Logics despite Institutional Complexity: An Inductive Study of Academic Inventors and Institutional Logics
    (English)Manuscript (preprint) (Other academic)
    National Category
    Health Care Service and Management, Health Policy and Services and Health Economy
    Identifiers
    urn:nbn:se:uu:diva-317933 (URN)
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-22
  • Public defence: 2017-06-01 13:15 Häggsalen, 10132, Uppsala
    Szaniawski, Piotr
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    From Light to Dark: Electrical Phenomena in Cu(In,Ga)Se2 Solar Cells2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Cu(In,Ga)Se2 (CIGS) solar cells the CIGS layer serves as the light absorber, growing naturally p-type. Together with an n-type buffer layer they form a p-n heterojunction. Typically, CdS is used as a buffer, although other, less toxic materials are investigated as alternatives. The intrinsic p-type doping of CIGS layers is the result of complex defect physics. Defect formation energies in CIGS are very low or even negative, which results in extremely high defect concentrations. This leads to many unusual electrical phenomena that can be observed in CIGS devices. This thesis mostly focuses on three of these phenomena: light-soaking, light-on-bias, and light-enhanced reverse breakdown.

    Light-soaking is a treatment that involves illuminating the investigated device for an extended period of time. In most CIGS solar cells it results in an improvement of open-circuit voltage, fill factor, and efficiency that can persist for hours, if not days. The interplay between light-soaking and the remaining two phenomena was studied. It was found that light-soaking has a strong effect on light-on-bias behavior, while the results for light-enhanced breakdown were inconclusive, suggesting little to no impact.

    Light-on-bias is a treatment which combines simultaneous illumination and application of reverse bias to the studied sample. Illuminating CdS-based samples with red light while applying a reverse bias results in a significant increase in capacitance due to filling of traps. In many cases, this is accompanied by a decrease in device performance under red illumination. Complete recovery is possible by illuminating the treated sample with blue light, which causes hole injection from the CdS buffer. In samples with alternative buffer layers, there is little distinction between red and blue illumination, and the increase in capacitance is milder. At the same time, there is little effect on device performance.

    Reverse breakdown can occur when a sufficiently large reverse bias is applied to a p-n junction, causing a large reverse current to flow through the device. In CIGS solar cells, the voltage at which breakdown occurs in darkness decreases in the presence of blue illumination. A model explaining the breakdown in darkness was proposed as a part of this thesis. The model assumes that all voltage drops on the buffer layer in darkness and on the CIGS layer under blue illumination. The high electric field in the buffer facilitates Poole-Frenkel conduction and Fowler-Nordheim tunneling between the absorber and the buffer.

    List of papers
    1. Light-enhanced reverse breakdown in Cu(In,Ga)Se2 solar cells
    Open this publication in new window or tab >>Light-enhanced reverse breakdown in Cu(In,Ga)Se2 solar cells
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    2013 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 535, 326-330 p.Article in journal (Refereed) Published
    Abstract [en]

    Partial shading of solar modules can subject shaded cells to significant reverse bias, often large enough toforce them into electrical breakdown, possibly resulting in irreversible damage. Therefore, better understandingof reverse current–voltage characteristics might lead to improvements in the design of solar modules. Thefocus of this study is the breakdown behavior of Cu(In,Ga)Se2 (CIGS) cells in darkness and under illumination.Two series of CIGS cells were investigated, with CdS and Zn–Sn–O buffer layers of varying thickness. Electricalbreakdown was found to be highly dependent on the buffer layer. Under blue illumination a remarkable decreasein breakdown voltage was observed for both buffer types. Metastable defects in the buffer/CIGS interfaceregion are tentatively proposed as the source of this effect and tunnelling is suggested as the mainmechanism responsible for breakdowns.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keyword
    copper indium gallium selenide, photoelectric properties, reverse breakdown, defects
    National Category
    Engineering and Technology Engineering and Technology
    Research subject
    Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-187534 (URN)10.1016/j.tsf.2012.09.022 (DOI)000318973600073 ()
    Funder
    StandUp
    Available from: 2012-12-07 Created: 2012-12-07 Last updated: 2017-04-04
    2. Influence of Varying Cu Content on Growth and Performance of Ga-Graded Cu(In,Ga)Se-2 Solar Cells
    Open this publication in new window or tab >>Influence of Varying Cu Content on Growth and Performance of Ga-Graded Cu(In,Ga)Se-2 Solar Cells
    Show others...
    2015 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 5, no 6, 1775-1782 p.Article in journal (Refereed) Published
    Abstract [en]

    Cu(In,Ga)Se-2 thin-film solar cells with Ga-graded absorber layers and a [Cu]/([In] + [Ga]) ratio varying between 0.5 and 1.0 were prepared by coevaporation and investigated. Except for the sample with a final [Cu]/([In] + [Ga]) ratio of 1.0, the samples were Cu-poor at all times during the evaporation. The variation in copper was found to influence the material properties in several ways: 1) Changing the Cu content had a strong impact on In and Ga interdiffusion, resulting in decreased Ga gradients in samples with large Cu deficiency; 2) the Cu-poor Cu(In, Ga)(3)Se-5 phase was detected in absorbers with [Cu]/([In] + [Ga]) ratios of 0.65 and below; and 3) the grain size changed significantly with the Cu variation. We observe a trend of reduced solar cell efficiencies for [Cu]/([In] + [Ga]) ratios of 0.65 and below, with an efficiency of 13.4% for the sample with a [Cu]/([In] + [Ga]) ratio of only 0.5, i.e., far from stoichiometry. We tentatively attribute the efficiency loss to a high concentration of point defects caused by the Cu deficiency.

    Keyword
    Coevaporation, Cu(In, Ga)Se-2 (CIGS), grading, interdiffusion
    National Category
    Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-268416 (URN)10.1109/JPHOTOV.2015.2478033 (DOI)000364098400041 ()
    Funder
    Swedish Energy AgencyStandUpEU, FP7, Seventh Framework Programme, 327367
    Available from: 2015-12-06 Created: 2015-12-04 Last updated: 2017-04-04Bibliographically approved
    3. A Systematic Study of Light-On-Bias Behavior in Cu(In,Ga)Se2 Solar Cells With Varying Absorber Compositions
    Open this publication in new window or tab >>A Systematic Study of Light-On-Bias Behavior in Cu(In,Ga)Se2 Solar Cells With Varying Absorber Compositions
    Show others...
    2017 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. PP, no 99, 1-10 p.Article in journal (Refereed) Published
    Keyword
    Capacitance;Charge measurement;Current measurement;Light emitting diodes;Lighting;Photovoltaic cells;Temperature measurement;Capacitance-voltage characteristics;current-voltage characteristics;degradation;deposition and characterization of thin film PV absorbers;photovoltaic cells;photovoltaic effects;thin film PV device properties and modeling
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-319426 (URN)10.1109/JPHOTOV.2017.2655148 (DOI)
    Available from: 2017-04-04 Created: 2017-04-04 Last updated: 2017-04-07
    4. Advancing the understanding of reverse breakdown in Cu(In,Ga)Se2 solar cells
    Open this publication in new window or tab >>Advancing the understanding of reverse breakdown in Cu(In,Ga)Se2 solar cells
    Show others...
    2017 (English)In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403Article in journal (Refereed) Accepted
    National Category
    Other Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:uu:diva-319442 (URN)
    Available from: 2017-04-04 Created: 2017-04-04 Last updated: 2017-04-28
  • Public defence: 2017-06-02 09:15 Å2001, Uppsala
    Pujari-Palmer, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Uppsala University.
    The biological and physical performance of high strength dicalcium phosphate cement in physiologically relevant models.2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The chemical properties of calcium phosphate cements (CPCs) are very similar to the mineral phase of bone. CPCs are, consequently, very effective substrates (scaffolds) for tissue engineering; bone and stem cells attach readily, and can proliferate and differentiate to form new bone tissue. Unlike other CPCs that may remain largely unchanged in the body for years, such as hydroxyapatite, dicalcium phosphates are remodelled by the body and rapidly converted to new bone. Unfortunately, the dicalcium phosphates are also typically too weak to support load bearing in the human body. Our laboratory has recently developed a novel, high strength brushite CPC, (hsCPC), which can reach 10-50 fold higher failure strength than many commercially available CPCs. The aim of this thesis was to investigate the physical, chemical and biological performance of hsCPCs in physiologically relevant model of drug release, load bearing, osteoconductivity, and as a scaffold for bone tissue engineering.

    Multiple CPCs were compared in a model of screw augmentation to determine whether the physical properties of the cement, such as bulk strength and porosity, affected orthopaedic screw holding strength. In an in vitro model of bone regeneration stem cells were grown on macroporous scaffolds that were fabricated from hsCPC. Drug releasing scaffolds were fabricated to examine whether the low porosity of hsCPC impeded drug release during a 4-week incubation period. The biological activity of an incorporated drug, Rebamipide, was examined after acute and chronic incubation periods. In the drug release study it was noted that the biological response to hsCPC was significantly greater than tissue culture grade polystyrene, even in scaffold groups without drug. The mechanism underlying this biological response was further investigated by testing the effect of pyrophosphate, a common cement additive, on bone cell proliferation and differentiation. This thesis concludes that a high strength cement can produce significant improvement in screw augmentation strength, if there is sufficient cortical bone near the augmentation site. The hsCPC is also cytocompatible, and can support bone and stem cell proliferation and differentiation. hsCPC scaffolds stimulated osteogenic gene expression comparable to native bone scaffolds. hsCPC scaffolds are also capable of delivering drug for up to 4 weeks, in vitro. Finally, a cement additive, pyrophosphate, stimulated differentiation but not proliferation of bone cells.

    List of papers
    1. Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out
    Open this publication in new window or tab >>Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Disease and injuries that affect the skeletal system may require surgical intervention and internal fixation, i.e. orthopedic plate and screw insertion, to stabilize the injury and facilitate tissue repair. If the surrounding bone quality is poor the screws may migrate, or the bone may fail, resulting in screw pull-out. Though numerous studies have shown that cement augmentation of the interface between bone and implant can increase screw holding strength in bone, the physical properties of cement that influence pull-out force have not been investigated. The present study sought to determine how the physical properties of calcium phosphate cements (CPCs), and the strength of the biological or synthetic material surrounding the augmented screw, affected the corresponding orthopedic screw pull-out force in urethane foam models of healthy and osteoporotic bone (Sawbones). In the simplest model, where only the bond strength between screw thread and cement (without Sawbone) was tested, the correlation between pull-out force and cement compressive strength (R2 = 0.79) was weaker than correlation with total cement porosity (R2 = 0.89). In open pore Sawbone that mimics “healthy” cancellous bone density the stronger cements produced higher pull-out force (50-60% increase). Higher strength, lower porosity, cements also produced higher pull-out forces (50-190% increase) in Sawbones with cortical fixation if the failure strength of the cortical material was similar to (bovine tibial bone), or greater than (metal shell), actual cortical bone. This result is of particular clinical relevance where fixation with a metal plate implant is indicated, as the nearby metal can simulate a thicker cortical shell and, thereby, increase the pull-out force of screws augmented with stronger cements. The improvement in pull-out force was apparent even at low augmentation volumes of 0.5 ml (50% increase), which suggest that in clinical situations where augmentation volume is limited the stronger, lower porosity CPCs may still produce a significant improvement in screw holding strength. When correlations of all the tested models were compared both cement porosity and compressive strength accurately predicted pull-out force (R2=1.00, R2=0.808), though prediction accuracy depended upon the strength of the material surrounding the Sawbone. The correlations strength was low for bone with no, or weak, cortical fixation. Higher strength and lower porosity CPCs also produced greater pull-out force (1-1.5 kN) than commercial CPC (0.2-0.5kN), but lower pull-out force than PMMA (2-3 kN). The results of this study suggest that the likelihood of screw fixation failure may be reduced by selecting calcium phosphate cements with lower porosity and higher bulk strength, in patients with healthy bone mineral density and/or sufficient cortical thickness. This is of particular clinical relevance when fixation with metal plates is indicated, or where the augmentation volume is limited.

    National Category
    Medical Materials
    Research subject
    Engineering Science with specialization in Materials Science
    Identifiers
    urn:nbn:se:uu:diva-320157 (URN)
    Funder
    Swedish Research Council, 262948EU, FP7, Seventh Framework Programme, 262948
    Available from: 2017-04-16 Created: 2017-04-16 Last updated: 2017-04-18
    2. Pyrophosphate Stimulates Differentiation, Matrix Gene Expression and Alkaline Phosphatase Activity in Osteoblasts
    Open this publication in new window or tab >>Pyrophosphate Stimulates Differentiation, Matrix Gene Expression and Alkaline Phosphatase Activity in Osteoblasts
    Show others...
    2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 10, e0163530Article in journal (Refereed) Published
    Abstract [en]

    Pyrophosphate is a potent mitogen, capable of stimulating proliferation in multiple cell types, and a critical participant in bone mineralization. Pyrophosphate can also affect the resorption rate and bioactivity of orthopedic ceramics. The present study investigated whether calcium pyrophosphate affected proliferation, differentiation and gene expression in early (MC3T3 pre-osteoblast) and late stage (SAOS-2 osteosarcoma) osteoblasts. Pyrophosphate stimulated peak alkaline phosphatase activity by 50% and 150% at 100 mu M and 0.1 mu M in MC3T3, and by 40% in SAOS-2. The expression of differentiation markers collagen 1 (COL1), alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OCN) were increased by an average of 1.5, 2, 2 and 3 fold, by high concentrations of sodium pyrophosphate (100 mu M) after 7 days of exposure in MC3T3. COX-2 and ANK expression did not differ significantly from controls in either treatment group. Though both high and low concentrations of pyrophosphate stimulate ALP activity, only high concentrations (100 mu M) stimulated osteogenic gene expression. Pyrophosphate did not affect proliferation in either cell type. The results of this study confirm that chronic exposure to pyrophosphate exerts a physiological effect upon osteoblast differentiation and ALP activity, specifically by stimulating osteoblast differentiation markers and extracellular matrix gene expression.

    National Category
    Biomaterials Science Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-307554 (URN)10.1371/journal.pone.0163530 (DOI)000385696900011 ()27701417 (PubMedID)
    Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2017-04-16Bibliographically approved
    3. Rebamipide Delivered by Brushite Cement Enhances Osteoblast and Macrophage Proliferation
    Open this publication in new window or tab >>Rebamipide Delivered by Brushite Cement Enhances Osteoblast and Macrophage Proliferation
    2015 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 10, no 5Article in journal (Refereed) Published
    Abstract [en]

    Many of the bioactive agents capable of stimulating osseous regeneration, such as bone morphogenetic protein-2 (BMP-2) or prostaglandin E2 (PGE2), are limited by rapid degradation, a short bioactive half-life at the target site in vivo, or are prohibitively expensive to obtain in large quantities. Rebamipide, an amino acid modified hydroxylquinoline, can alter the expression of key mediators of bone anabolism, cyclo-oxygenase 2 (COX-2), BMP-2 and vascular endothelial growth factor (VEGF), in diverse cell types such as mucosal and endothelial cells or chondrocytes. The present study investigates whether Rebamipide enhances proliferation and differentiation of osteoblasts when delivered from brushite cement. The reactive oxygen species (ROS) quenching ability of Rebampide was tested in macrophages as a measure of bioactivity following drug release incubation times, up to 14 days. Rebamipide release from brushite occurrs via non-fickian diffusion, with a rapid linear release of 9.70%+/- 0.37% of drug per day for the first 5 days, and an average of 0.5%-1% per day thereafter for 30 days. Rebamipide slows the initial and final cement setting time by up to 3 and 1 minute, respectively, but does not significantly reduce the mechanical strength below 4% (weight percentage). Pre-osteoblast proliferation increases by 24% upon exposure to 0.4uM Rebamipide, and by up to 73% when Rebamipide is delivered via brushite cement. Low doses of Rebamipide do not adversely affect peak alkaline phosphatase activity in differentiating pre-osteoblasts. Rebamipide weakly stimulates proliferation in macrophages at low concentrations (118 +/- 7.4% at 1uM), and quenches ROS by 40-60%. This is the first investigation of Rebamipide in osteoblasts.

    National Category
    Other Engineering and Technologies
    Identifiers
    urn:nbn:se:uu:diva-257022 (URN)10.1371/journal.pone.0128324 (DOI)000355319400083 ()26023912 (PubMedID)
    Available from: 2015-06-29 Created: 2015-06-29 Last updated: 2017-04-16Bibliographically approved
    4. Fabrication of rnacroporous cement scaffolds using PEG particles: In vitro evaluation with induced pluripotent stem cell-derived mesenchymal progenitors
    Open this publication in new window or tab >>Fabrication of rnacroporous cement scaffolds using PEG particles: In vitro evaluation with induced pluripotent stem cell-derived mesenchymal progenitors
    Show others...
    2016 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 69, 640-652 p.Article in journal (Refereed) Published
    Abstract [en]

    Calcium phosphate cements (CPCs) have been extensively used in reconstructive dentistry and orthopedics, but it is only recently that CPCs have been combined with stem cells to engineer biological substitutes with enhanced healing potential. In the present study, macroporous CPC scaffolds with defined composition were fabricated using an easily reproduced synthesis method, with minimal fabrication and processing steps. Scaffold pore size and porosity, essential for cell infiltration and tissue ingrowth, were tuned by varying the content and size of polyethylene glycol (PEG) particles, resulting in 9 groups with different architectural features. The scaffolds were characterized for chemical composition, porosity and mechanical properties, then tested in vitro with human mesenchymal progenitors derived from induced pluripotent stem cells (iPSC-MPs). Biomimetic decellularized bone scaffolds were used as reference material in this study. Our manufacturing process resulted in the formation of macroporous monetite scaffolds with no residual traces of PEG. The size and content of PEG particles was found to affect scaffold porosity, and thus mechanical properties. Irrespective of pore size and porosity, the CPC scaffolds fabricated in this study supported adhesion and viability of human iPSC-MPs similarly to decellularized bone scaffolds. However, the architectural features of the scaffolds were found to affect the expression of bone specific genes, suggesting that specific scaffold groups could be more suitable to direct human iPSC-MPs in vitro toward an osteoblastic phenotype. Our simplistic fabrication method allows rapid, inexpensive and reproducible construction of macroporous CPC scaffolds with tunable architecture for potential use in dental and orthopedic applications.

    Keyword
    Bioinaterial scaffold, Calcium phosphate cement, Macroporosity, Mesenchymal progenitors, Induced pluripotent stem cells, Tissue engineering
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-306232 (URN)10.1016/j.msec.2016.06.075 (DOI)000383930900076 ()27612757 (PubMedID)
    Funder
    EU, FP7, Seventh Framework Programme, 262948
    Available from: 2016-10-27 Created: 2016-10-26 Last updated: 2017-04-16Bibliographically approved
  • Public defence: 2017-06-02 09:15 Rosénsalen, Uppsala
    Nylander, Ruta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Magnetic resonance imaging markers of cerebral small vessel disease in an elderly population – association with cardiovascular disease and cognitive function2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cerebral small vessel disease (SVD) is identifiable by clinical, neuroimaging, neuropathological and cognitive findings.

    The aim of this thesis was to assess SVD and cerebral perfusion on magnetic resonance imaging (MRI) in a 75-year-old population and compare the findings with scars of myocardial infarctions, cardiovascular risk markers and cognitive function. In addition, the evolution of SVD over 5 years was studied.

    The study population included subjects from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. The subjects had been chosen in a randomized manner from the register of the municipality. MRI of the brain and the heart, cognitive tests and blood tests for cardiovascular risk factors were performed in 406 subjects at age 75 years and 250 of them were re-examined 5 years later at the age of 80.

    Paper 1 showed that unrecognized myocardial infarctions (UMIs) were found in 120 subjects (30%) and recognized myocardial infarctions (RMIs) in 21 (5%). Men with RMIs displayed an increased prevalence of cortical and lacunar cerebral infarctions, whereas women with UMIs more frequently had cortical cerebral infarctions.

    Paper 2 showed that one or more brain infarcts were seen in 23% of the subjects (20% had only lacunar infarcts, 1% had only cortical infarcts and 2% had both). Hypertension and obesity were significantly associated with an increased risk of infarction.  The newer risk markers investigated were not significantly associated with brain infarcts.

    Paper 3 showed that MRI manifestations of SVD progressed over 5 years. Relative cerebral blood flow (rCBF) was not associated with WMH volume or progression of WMH volume.

    Paper 4 showed that moderate to severe WMHs and incident lacunar infarcts on brain MRI were associated with a mild impairment of executive function.

    In conclusion, this longitudinal population based study compares MRI manifestations of SVD with clinical data, providing knowledge that may be used in further investigations of preventive interventions and for identification of disease in early stages.

     

    List of papers
    1. Prevalence of unrecognized myocardial infarction detected with magnetic resonance imaging and its relationship to cerebral ischemic lesions in both sexes
    Open this publication in new window or tab >>Prevalence of unrecognized myocardial infarction detected with magnetic resonance imaging and its relationship to cerebral ischemic lesions in both sexes
    Show others...
    2011 (English)In: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597, Vol. 58, no 13, 1372-1377 p.Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVES: The purpose of this study was to investigate the prevalence of unrecognized myocardial infarction (UMI) detected with magnetic resonance imaging (MRI) and whether it is related to cerebral ischemic lesions on MRI in an elderly population-based cohort.

    BACKGROUND: There is a correlation between stroke and recognized myocardial infarction (RMI) and between stroke and UMI detected with electrocardiography, whereas the prevalence of stroke in subjects with MRI-detected UMI is unknown.

    METHODS: Cerebral MRI and cardiac late-enhancement MRI were performed on 394 randomly selected 75-year-old subjects (188 women, 206 men). Images were assessed for cerebral ischemic lesions and myocardial infarction (MI) scars. Medical records were scrutinized. Subjects with MI scars, with or without a hospital diagnosis of MI, were classified as RMI or UMI, respectively.

    RESULTS: UMIs were found in 120 subjects (30%) and RMIs in 21 (5%). The prevalence of UMIs (p = 0.004) and RMIs (p = 0.02) was greater in men than in women. Men with RMI displayed an increased prevalence of cortical and lacunar cerebral infarctions, whereas women with UMI more frequently had cortical cerebral infarctions (p = 0.003).

    CONCLUSIONS: MI scars are more frequent in men than in women at 75 years of age. The prevalence of RMI is related to that of cerebral infarctions.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-160996 (URN)10.1016/j.jacc.2011.06.028 (DOI)21920267 (PubMedID)
    Available from: 2011-11-04 Created: 2011-11-04 Last updated: 2017-04-10Bibliographically approved
    2. Relation between Cardiovascular Disease Risk Markers and Brain Infarcts Detected by Magnetic Resonance Imaging in an Elderly Population
    Open this publication in new window or tab >>Relation between Cardiovascular Disease Risk Markers and Brain Infarcts Detected by Magnetic Resonance Imaging in an Elderly Population
    Show others...
    2015 (English)In: Journal of Stroke & Cerebrovascular Diseases, ISSN 1052-3057, E-ISSN 1532-8511, Vol. 24, no 2, 312-318 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND:

    Established cardiovascular risk markers, such as hypertension, are associated with increased risk of brain infarcts. The newer markers N-terminal pro-brain natriuretic peptide, troponin I, C-reactive protein, and cystatin C may affect the risk of cardiovascular events and potentially, thereby, also stroke. We investigated the association between established and new risk markers for cardiovascular disease and brain infarcts detected by magnetic resonance imaging (MRI) at age 75.

    METHODS:

    Four hundred six randomly selected subjects from the Prospective Investigation of the Vasculature in Uppsala Seniors study were examined with MRI of the brain at age 75. Blood samples, measurements, and dedicated questionnaires at age 70 were used for analysis of risk markers. A history of diseases had been obtained at age 70 and 75. MRI was evaluated regarding lacunar and cortical infarcts. Univariate associations between outcomes and risk markers were assessed with logistic regression models.

    RESULTS:

    One or more infarcts were seen in 23% of the subjects (20% had only lacunar infarcts, 1% had only cortical infarcts, and 2% had both). Hypertension (odds ratio [OR] 2.6, 95% confidence interval [CI] 1.4, 4.7) and obesity (OR 1.3; CI 1.0, 1.8) were significantly associated with increased risk of brain infarction. The newer risk markers were not significantly associated with the brain infarcts.

    CONCLUSIONS:

    The new markers were not associated with the predominantly lacunar infarcts in our 75-year-old population, why troponin I and NT-proBNP may be associated mainly with cardioembolic infarcts as shown recently.

    National Category
    Clinical Medicine
    Identifiers
    urn:nbn:se:uu:diva-238456 (URN)10.1016/j.jstrokecerebrovasdis.2014.08.027 (DOI)000349177300010 ()25444032 (PubMedID)
    Available from: 2014-12-12 Created: 2014-12-12 Last updated: 2017-04-10Bibliographically approved
    3. Quantitative and qualitative MRI evaluation of cerebral small vessel disease in an elderly population: a longitudinal study
    Open this publication in new window or tab >>Quantitative and qualitative MRI evaluation of cerebral small vessel disease in an elderly population: a longitudinal study
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-319612 (URN)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-10
    4. Small vessel disease on neuroimaging in elderly individuals: association with cognitive and executive tests
    Open this publication in new window or tab >>Small vessel disease on neuroimaging in elderly individuals: association with cognitive and executive tests
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:uu:diva-319613 (URN)
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2017-04-10
  • Public defence: 2017-06-02 10:15 Brusewitzsalen, Statsvetenskapliga institutionen, Uppsala
    Moberg, Linda
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Government.
    Marketization in Swedish Eldercare: Implications for Users, Professionals, and the State2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    During the last decades, Swedish policy makers have implemented various marketization reforms into the public welfare sector in order to make it more cost-efficient and to improve its quality. The aim of this dissertation is to investigate what implications this marketization trend has had for the organization of Swedish eldercare. In particular, the research question addressed is how marketization reforms such as privatized provision, increased competition, and user choice have transformed the relationship between the service users, the professionals, and the state. To answer the research question, four articles are presented in the dissertation, each corresponding to a separate empirical investigation. Together, the articles demonstrate that the increased reliance on marketization in Swedish eldercare has made it more difficult for the local authorities to directly control the quality of the services, since it reduces their ability to allocate public resources and expects them to govern the provision of eldercare through the entering of contracts. This development has also implied that service users themselves become increasingly responsible for ensuring that the quality of their care is high. Moreover, the articles show that the increased reliance on audit by the national government and its agencies has tended to undermine the professionalization of eldercare staff, thereby limiting their autonomy and ability to ensure service quality. As a whole, the dissertation contributes with a more comprehensive understanding of how marketization has altered the organization of Swedish eldercare and under what conditions it might undermine the goals of social equality and ensuring that all citizens have equal access to good quality care.

    List of papers
    1. User choice in Swedish eldercare: conditions for informed choice and enhanced service quality
    Open this publication in new window or tab >>User choice in Swedish eldercare: conditions for informed choice and enhanced service quality
    2016 (English)In: Journal of European Social Policy, ISSN 0958-9287, E-ISSN 1461-7269, Vol. 26, no 3, 281-295 p.Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    Proponents of user choice argue that this type of policy arrangement improves the quality of public social services since users are expected to select the most highly performing providers. In order for users to make informed choices, however, they need quality information about the services offered by different providers. In this article, we carry out a case study, investigating whether information about service quality was presented to users of home-based elderly care in Sweden. The analysis is based on unique data regarding the information of 223 providers in 10 municipalities. The results suggest that the information was poor and lacking in important quality dimensions. This indicates a lack of real user power since it is virtually impossible for users to make informed choices without relevant information. It also makes it less likely that the general quality level of home-based services will increase as a result of the user choice.

    Keyword
    Elderly care, informed choice, quality information, service quality, user choice
    National Category
    Health Care Service and Management, Health Policy and Services and Health Economy Political Science
    Identifiers
    urn:nbn:se:uu:diva-299847 (URN)10.1177/0958928716645076 (DOI)000378792600006 ()
    Funder
    Swedish Research Council
    Available from: 2016-07-29 Created: 2016-07-28 Last updated: 2017-04-05
    2. Marketisation of Nordic Eldercare – Is the Model Still Universal?
    Open this publication in new window or tab >>Marketisation of Nordic Eldercare – Is the Model Still Universal?
    2016 (English)In: Journal of Social Policy, ISSN 0047-2794, E-ISSN 1469-7823Article in journal (Refereed) Published
    Abstract [en]

    The objective of this article is to analyse whether the increased reliance on marketisation in the provision of social care challenges the universality of eldercare in Sweden, Denmark, Finland and Norway. The study focuses on national reforms for contracting out and user choice of provider, analysing their consequences for four universalistic dimensions: (i) equal inclusion, (ii) public funding, (iii) public provision and (iv) comprehensive usage. The findings suggest that, although need-based inclusion and public funding remain key principles in all four countries, there is an increased reliance on private provision in Sweden, Denmark and Finland. In addition, the introduction of topping-up services challenges the dimension of comprehensive usage by enabling users with economic resources to turn to the private market to increase the comprehensiveness and quality of their care.

    Keyword
    Universalism, Marketization, Welfare state, Nordic countries, Social Policy, Eldercare
    National Category
    Social Sciences
    Research subject
    Political Science
    Identifiers
    urn:nbn:se:uu:diva-317314 (URN)10.1017/S0047279416000830 (DOI)
    Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-04-05
    3. Professionalized through audit?: Care workers and the new audit regime in Sweden
    Open this publication in new window or tab >>Professionalized through audit?: Care workers and the new audit regime in Sweden
    (English)In: Social Policy & Administration, ISSN 0144-5596, E-ISSN 1467-9515Article in journal (Other academic) Submitted
    Abstract [en]

    The objective of this article is to analyze whether the audit processes adopted in Swedish eldercare and childcare support or undermine the professionalization of the occupations working there, that is, nurses, nursing assistants, pre-school teachers and child minders. In particular we investigate whether the three main forms of audit; standard-setting, inspections and quality measurements, support or undermine the occupations’ ability to achieve professional closure and enhance their external and internal autonomy. The paper finds that the audit process adapted in eldercare is non-supportive of the professionalization of both nurses and nursing assistants. In childcare, however, it appears to support professional development, particularly for pre-school teachers. These findings suggest that audit processes do not have to be detrimental to professionalization. Instead, it appears that the state can design them in such a way that they make visible and close the work tasks of specific staff groups and thereby support, rather than undermine, their professional development

    Keyword
    Professionalization, Audit, Social care, Eldercare, Child care
    National Category
    Social Sciences Public Administration Studies
    Identifiers
    urn:nbn:se:uu:diva-319246 (URN)
    Available from: 2017-04-02 Created: 2017-04-02 Last updated: 2017-04-05
    4. User choice and the changing notion of social citizenship in Swedish eldercare
    Open this publication in new window or tab >>User choice and the changing notion of social citizenship in Swedish eldercare
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    This article aims to analyze how the policy makers who crafted the Swedish choice reform in eldercare reasoned with regard to the tension between user choice and citizens’ right to quality care. To answer this question, three dimensions are addressed in the paper: (i) what role did the choice reform assign to the users and how did the policy makers view their ability to make informed choices? (ii) How did the policy makers view the role of the public authorities and what tools were they given to ensure citizens’ equal access to good quality eldercare? (iii) Did the policies entail a new form of social citizenship for the elderly? The findings suggest that while Swedish policy makers introduced a system where eldercare users were encouraged to make free choices between providers, thereby allocating resources among these, the users also became more responsible to ensure service quality through their choices. In addition, the choice reform altered the regulatory role of local authorities who no longer had full control over the resource distribution and also become more restricted in their regulatory abilities. Furthermore, the paper argues that the Swedish choice reform entails a more libertarian notion of social citizenship, implying that users are to take on greater responsibility for their own well-being and protection against social risks.

    Keyword
    Social citizenship, User choice, Eldercare, Sweden, Social rights
    National Category
    Political Science Public Administration Studies
    Identifiers
    urn:nbn:se:uu:diva-319248 (URN)
    Available from: 2017-04-02 Created: 2017-04-02 Last updated: 2017-04-05
  • Public defence: 2017-06-02 13:00 Krusenstjernasalen - Biblioteket, Högskolan i Gävle, Gävle
    Jackson, Jennie A
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences. Högskolan i Gävle, Avdelningen för arbets- och folkhälsovetenskap.
    Bias and Precision in Biomechanical Exposure Assessment: Making the Most of our Methods2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Insufficient exposure assessment is a suggested contributing factor to the current lack of clearly characterised relationships between occupational biomechanical risk factors and musculoskeletal disorders. Minimal attention has been paid to the potential bias of measurement tools from expected true values (i.e. accuracy) or between measurement tools, and empirical data on the magnitudes of variance contributed by methodological factors for measurement tool precision are lacking.

    Aim: The aim of this thesis was to quantify aspects of bias and precision in three commonly employed biomechanical risk factor assessment tools - inclinometry, observation, and electromyography (EMG) - and provide recommendations guiding their use.

    Methods: Upper arm elevation angles (UAEAs) were assessed using inclinometers (INC) and by computer-based posture-matching observation, and bias relative to true angles was calculated. Calibration models were developed for INC data, and their efficacy in correcting measurement bias was evaluated. The total variance of trapezius and erector spinae (ES) EMG recordings during cyclic occupational work was partitioned into biological and methodological sources, including the variance uniquely attributable to sub-maximal normalisation. Using algorithms to estimate the precision of a group mean, the efficacy of different trapezius EMG study designs was evaluated. Using precision criteria, the efficacy of different normalisation methods was assessed for ES EMG recordings.

    Results and Discussion: Inclinometer measured UAEAs were biased from true angles, with increasing bias at higher angles. In contrast, computer based posture-matching observations were not biased from true angles.  Calibration models proved effective at minimizing INC data bias. The dispersion of estimates between- and within- observers at any given set angle underlined the importance of repeated observations when estimating UAEAs.  For EMG, a unique but relatively small component of the total variance was attributable to the methodological process of normalisation. Performing three repeats of the trapezius EMG normalisation task proved optimal at minimizing variance for one-day EMG studies, while two repeats sufficed for multi-day EMG studies. A prone normalisation task proved superior for maximizing normalised lumbar ES EMG precision.

    Conclusion: Key aspects of measurement tool accuracy, bias between tools, and tool precision were quantified, and recommendations were made to guide future research study design.

    List of papers
    1. Is what you see what you get?: Standard inclinometry of set upper arm elevation angles
    Open this publication in new window or tab >>Is what you see what you get?: Standard inclinometry of set upper arm elevation angles
    Show others...
    2015 (English)In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 47, 242-252 p.Article in journal (Refereed) Published
    Abstract [en]

    Previous research suggests inclinometers (INC) underestimate upper arm elevation. This study was designed to quantify possible bias in occupationally relevant postures, and test whether INC performance could be improved using calibration. Participants were meticulously positioned in set arm flexion and abduction angles between 0 degrees and 150 degrees. Different subject-specific and group-level regression models comprising linear and quadratic components describing the relationship between set and INC-registered elevation were developed using subsets of data, and validated using additional data. INC measured arm elevation showed a downward bias, particularly above 600. INC data adjusted using the regression models were superior to unadjusted data; a subject-specific, two-point calibration based on measurements at 0 and 900 gave results closest to the 'true' set angles. Thus, inclinometer measured arm elevation data required calibration to arrive at 'true' elevation angles. Calibration to a common measurement scale should be considered when comparing arm elevation data collected using different methods.

    Keyword
    Measurement error, Observation, Working postures
    National Category
    Environmental Health and Occupational Health
    Identifiers
    urn:nbn:se:uu:diva-245337 (URN)10.1016/j.apergo.2014.08.014 (DOI)000347663600028 ()25479994 (PubMedID)
    Available from: 2015-03-03 Created: 2015-02-26 Last updated: 2017-04-07Bibliographically approved
    2. Observer performance in estimating upper arm elevation angles under ideal viewing conditions when assisted by posture matching software
    Open this publication in new window or tab >>Observer performance in estimating upper arm elevation angles under ideal viewing conditions when assisted by posture matching software
    2016 (English)In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 55, 208-215 p.Article in journal (Refereed) Published
    Abstract [en]

    Selecting a suitable body posture measurement method requires performance indices of candidate tools. Such data are lacking for observational assessments made at a high degree of resolution. The aim of this study was to determine the performance (bias and between- and within-observer variance) of novice observers estimating upper arm elevation postures assisted by posture matching software to the nearest degree from still images taken under ideal conditions. Estimates were minimally biased from true angles: the mean error across observers was less than 2. Variance between observers was minimal. Considerable variance within observers, however, underlined the risk of relying on single observations. Observers were more proficient at estimating 0 and 90 postures, and less proficient at 60. Thus, under ideal visual conditions observers, on average, proved proficient at high resolution posture estimates; further investigation is required to determine how non-optimal image conditions, as would be expected from occupational data, impact proficiency.

    Keyword
    Measurement error, Working postures, Observation
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology
    Identifiers
    urn:nbn:se:uu:diva-300293 (URN)10.1016/j.apergo.2016.01.012 (DOI)000374074600021 ()26995050 (PubMedID)
    Funder
    Forte, Swedish Research Council for Health, Working Life and Welfare, 2009-1761
    Available from: 2016-08-08 Created: 2016-08-08 Last updated: 2017-04-07Bibliographically approved
    3. Methodological variance associated with normalization of occupational upper trapezius EMG using sub-maximal reference contractions
    Open this publication in new window or tab >>Methodological variance associated with normalization of occupational upper trapezius EMG using sub-maximal reference contractions
    2009 (English)In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 19, no 3, 416-427 p.Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVES: To quantify the variance introduced to trapezius electromyography (EMG) through normalization by sub-maximal reference voluntary exertions (RVE), and to investigate the effect of increased normalization efforts as compared to other changes in data collection strategy on the precision of occupational EMG estimates.

    METHODS: Women performed four RVE contractions followed by 30 min of light, cyclic assembly work on each of two days. Work cycle EMG was normalized to each of the RVE trials and seven exposure parameters calculated. The proportions of exposure variance attributable to subject, day within subject, and cycle and normalization trial within day were determined. Using this data, the effect on the precision of the exposure mean of altering the number of subjects, days, cycles and RVEs during data collection was simulated.

    RESULTS: For all exposure parameters a unique component of variance due to normalization was present, yet small: less than 4.4% of the total variance. The resource allocation simulations indicated that marginal improvements in the precision of a group exposure mean would occur above three RVE repeats for EMG collected on one day, or beyond two RVEs for EMG collected on two or more days.

    National Category
    Environmental Health and Occupational Health
    Identifiers
    urn:nbn:se:uu:diva-314744 (URN)10.1016/j.jelekin.2007.11.004 (DOI)18155593 (PubMedID)
    Available from: 2017-02-06 Created: 2017-02-06 Last updated: 2017-04-07Bibliographically approved
    4. Precision based guidelines for sub-maximal normalisation task selection for trunk extensor EMG
    Open this publication in new window or tab >>Precision based guidelines for sub-maximal normalisation task selection for trunk extensor EMG
    2017 (English)In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711Article in journal (Refereed) Submitted
    Abstract [en]

    Aim: The object of this study was to quantify the contribution of sub-maximal normalisation to the overall variance of exposure parameters describing erector spinae (ES) activity, and to provide guidelines for task selection which minimize methodological variance. Methods: ES EMG was measured from three locations (T9, L1 and L5 levels) on fifteen men performing a manual materials handling task in the laboratory on three separate days. Four repeats of each of eleven sub-maximal normalisation tasks (eight static, three dynamic) were collected, work data were normalised to each task and repeat, and exposure parameters calculated. The unique contribution of normalisation to the overall variance was determined for each task and exposure parameter using variance component analyses. Normalisation tasks were scored according to their relative contributions to the overall variance and coefficients of variation.

    Results: A prone task, similar to the Biering-Sørensen test posture, was the most repeatable for all electrode locations and across all exposure parameters. Thoracic level normalisation typically showed poorer repeatability than lumbar normalisation.

    Discussion: We recommend that future ES EMG studies employing sub-maximal normalisation utilise said prone task. An alternate normalisation task specific to thoracic level ES muscles may be warranted.

    Keyword
    Exposure variability, variance components, low back, lumbar, erector spinae
    National Category
    Environmental Health and Occupational Health
    Identifiers
    urn:nbn:se:uu:diva-314783 (URN)
    Funder
    Forte, Swedish Research Council for Health, Working Life and Welfare, 2009-1761]
    Available from: 2017-01-20 Created: 2017-02-06 Last updated: 2017-04-07Bibliographically approved
  • Public defence: 2017-06-02 13:00 Norrlands 1 & 2, Uppsala
    Jackson, Illiam
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Palaeobiology.
    Morphometric analysis of Cambrian fossils and its evolutionary significance2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Extended Evolutionary Synthesis (EES) is currently emerging as a theoretical alternative to the Modern Synthesis (MS) in which to frame evolutionary observations and interpretations. These alternative frameworks differ fundamentally in their understanding of the relative roles of the genotype, phenotype, development and environment in evolutionary processes and patterns. While the MS represents a gene-centred view of evolution, the EES instead emphasizes the interactions between organism, development and environment. This novel theoretical framework has generated a number of evolutionary predictions that are mutually incompatible with the equivalent of the MS. While research and empirical testing has begun on a number of these in a neontological context, the field of palaeontology has yet to contribute meaningfully to this endeavour. One of the reasons for this is a lack of methodological approaches capable of investigating relevant evolutionary patterns in the fossil record. In this thesis morphometric methods capable of providing relevant data are developed and employed in the analysis of Cambrian fossils. Results of these analyses provide empirical support for the process of evolution through phenotypic plasticity and genetic assimilation hypothesized by the EES. Furthermore, theoretical revision to the species concept in a palaeontological context is suggested. Finally, predictions of the EES specific to the fossil record are made explicit and promising directions of future research are outlined.

    List of papers
    1. Intraspecific morphological variation of Agnostus pisiformis, a Cambrian Series 3 trilobite-like arthropod
    Open this publication in new window or tab >>Intraspecific morphological variation of Agnostus pisiformis, a Cambrian Series 3 trilobite-like arthropod
    (English)In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931Article in journal (Refereed) Epub ahead of print
    Abstract [en]

    The study of evolution in a palaeontological context is chiefly the study of change in shape and form. This requires data sets that quantify morphology and morphological variation. Historically morphology has been described using discrete characters or more recently using various morphometric approaches. Elliptical Fourier analysis (EFA) is an approach to quantifying morphology that results in the production of large data sets of elliptical Fourier descriptors (EFDs), which are highly suitable to multivariate analysis. EFA is used in this paper to quantify the shape and describe the ontogeny of Agnostus pisiformis (Wahlenberg 1818: Nova Acta Regiae Societatis Scientiarum Upsaliensis 8, 1), a trilobite-like arthropod of Cambrian Series 3, from three coeval localities in Sweden. An ontogenetic difference was detected between geographically distant populations from Västergötland and Skåne in Sweden. These differences are probably the result of environmental dysoxic stress leading to increasing phenotypic variation. These findings illustrate the utility of EFA applied to the study of fossil organisms; permitting studies of such high resolution that multiple assemblages of the same species can be comparatively studied to achieve a more detailed understanding of their morphological and ontogenetic variation.

    Keyword
    Agnostus pisiformis, Alum Shale, elliptical Fourier analysis, intraspecific variation, morphometrics
    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319483 (URN)10.1111/let.12201 (DOI)
    Available from: 2017-04-05 Created: 2017-04-05 Last updated: 2017-04-12Bibliographically approved
    2. Morphometric Analysis of the Early Cambrian mollusc Mackinnonia and the Incipient Species Concept
    Open this publication in new window or tab >>Morphometric Analysis of the Early Cambrian mollusc Mackinnonia and the Incipient Species Concept
    (English)In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983Article in journal (Other academic) Submitted
    Abstract [en]

    Phylogenetic relationships within the helcionelloids have been difficult to establish. One of the reasons for this is that qualitative approaches to investigating morphological variation in this group have struggled to identify clear patterns. An alternative method of identifying these patterns is to study these organisms quantitatively. Here we exemplify this approach by employing morphometric methods to investigate patterns of subtle morphological variation in two species of Mackinnonia Runnegar in Bengtson et al. Specifically, we conduct a combination of elliptical Fourier and multivariate analyses to study intra- and interspecific variation in protoconch form and variation in ontogenetic trajectory of two species of Mackinnonia. The material we use consists of two assemblages of Mackinnonia rostrata (Zhou & Xiao), from the Shackleton Limestone of Antarctica and Ajax Limestone of Australia, and an assemblage of Mackinnonia taconica (Landing & Bartowski) from the Bastion Formation of Greenland. Results of our study show significant (p=<0.0001) differences in protoconch shape between all three groups. Ontogenetic sequences of outline curves truncated at successive rugae significantly (p=<0.05) discriminate between M. rostrata and M. taconica. We discuss the uncovered significant intraspecific morphological variation of disparate assemblages of M. rostrata despite shared qualitative features and develop a conceptual framework for understanding such patterns of variation. We define the incipient species concept using Mackinnonia as an empirical example.

    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319485 (URN)
    Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2017-04-19
    3. Genetic assimilation in the fossil record: phenotypic plasticity and later accommodation in Cambrian arthropods
    Open this publication in new window or tab >>Genetic assimilation in the fossil record: phenotypic plasticity and later accommodation in Cambrian arthropods
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Genetic assimilation is a hypothesised process in which an initially plastic developmental phenotypic response of an organism to the environment is fixed genetically, i.e. assimilated into its genome 1,2. One central prediction of genetic assimilation is that “phenotypic accommodation can precede, rather than follow, genetic change, in adaptive evolution”3. Here we test this prediction in the fossil record. Agnostus pisiformis, a Cambrian Series 3 trilobite-like arthropod, has been shown to exhibit subtly different patterns of pygidial morphological variation across coeval assemblages4, varying chiefly in the degree to which the axial lobe dominates the pygidium. We demonstrate that this morphological variation as well as that of the slightly younger closely related Homagnostus obesus is significantly correlated with geochemical indicators of dysoxia/euxinia and thus stressed environments5-7. In addition, the variances of high and low-stress assemblages also differ significantly, suggesting that the morphological variability of the different assemblages is induced by environmental stress and can be understood as a reaction norm8. We include in our analysis the younger relative Trilobagnostus holmi and interpret its morphology, which has a strongly reduced variance, as representing a more canalized9 or stabilized1 stage of the assimilation process. Thus our data contain all stages of adaptation via phenotypic plasticity and genetic assimilation10 and support the main predictions of the ‘Extended Evolutionary Synthesis’3.

    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319484 (URN)
    Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2017-04-19
    4. The Extended Evolutionary Synthesis in the fossil record
    Open this publication in new window or tab >>The Extended Evolutionary Synthesis in the fossil record
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The Extended Evolutionary Synthesis (EES) has recently emerged as a theoretical alternative or complement to the Modern Synthesis (MS) in which to frame evolutionary observations and interpretations. The theoretical framework of the EES places a greater evolutionary significance on a number of controversial hypotheses and processes, such as phenotypic plasticity and genetic assimilation, and makes a number of empirical predictions based thereon. Investigation and empirical exploration of these predictions has begun in a neontological context yet the field of palaeontology has not yet been instrumental in developing or testing these predictions. Here the hypothetical process of evolution via phenotypic plasticity and genetic assimilation is explained and contextualised to the fossil record. A prediction of the EES specific to palaeontological data is formulated and methods suitable for its empirical testing are suggested.

    National Category
    Evolutionary Biology
    Identifiers
    urn:nbn:se:uu:diva-319486 (URN)
    Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2017-04-15
  • Public defence: 2017-06-02 13:15 Siegbahnsalen, Uppsala
    Andersson, Mikael Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Interacting Magnetic Nanosystems: An Experimental Study Of Superspin Glasses2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents experimental results on strongly interacting γ-Fe2O3 magnetic nanoparticles and their collective properties. The main findings are that very dense randomly packed (≈60%) γ-Fe2O3 nanoparticles form a replica of a spin glass. The magnetic properties of the nanoparticle system are in most regards the same as those of an atomic spin glass. The system is therefore proposed as a model superspin glass. In superspin glasses the interacting building blocks that form the collective state are single domain nanoparticles, superspins with a magnetic moment of about 10000 μB, which can be compared to the atomic magnetic moment in spin glasses of approximately 1 μB.  It was found that the relaxation time of the individual nanoparticles impacts the collective properties and governs the superspin dimensionality. Several dense compacts, each prepared with nanoparticles of a specific size, with diameters 6, 8, 9 and 11.5 nm, were studied. All the studied compacts were found to form a superspin glass state. Non-interacting reference samples, consisting of the same particles but coated with a silica shell, were synthesized to determine the single particle magnetic properties.  It was also found that the effects of the nanoparticle size distribution, which lead to a variation of the magnetic properties, can be mitigated by having strong enough interparticle interactions. The majority of the work was carried out using SQUID magnetometry.

    List of papers
    1. Ageing dynamics of a superspin glass
    Open this publication in new window or tab >>Ageing dynamics of a superspin glass
    Show others...
    2014 (English)In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 108, no 1, 17004- p.Article in journal (Refereed) Published
    Abstract [en]

    Magnetization dynamics of a model superspin glass system consisting of nearly monodispersed close-packed maghemite particles of diameter 8 nm is investigated. The observed non-equilibrium features of the dynamics are qualitatively similar to those of atomic spin glass systems. The intrinsic relaxation function, as observed in zero-field-cooled magnetization relaxation experiments, depends on the time the sample has been kept at constant temperature (ageing). Accompanying low-field experiments show that the archetypal spin glass characteristics -ageing, memory and rejuvenation- are reproduced in this dense system of dipolar-dipolar interacting superspins.  

    National Category
    Materials Engineering Physical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-238588 (URN)10.1209/0295-5075/108/17004 (DOI)000343970300018 ()
    Available from: 2014-12-16 Created: 2014-12-14 Last updated: 2017-04-07Bibliographically approved
    2. Size-dependent surface effects in maghemite nanoparticles and its impact on interparticle interactions in dense assemblies
    Open this publication in new window or tab >>Size-dependent surface effects in maghemite nanoparticles and its impact on interparticle interactions in dense assemblies
    Show others...
    2015 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, no 47, 475703Article in journal (Refereed) Published
    Abstract [en]

    The question of the dominant interparticle magnetic interaction type in random closely packed assemblies of different diameter (6.2-11.5 nm) bare maghemite nanoparticles (NPs) is addressed. Single-particle magnetic properties such as particle anisotropy and exchange bias field are first of all studied in dilute (reference) systems of these same NPs, where interparticle interactions are neglible. Substantial surface spin disorder is revealed in all particles except the smallest, viz. for diameters d = 8-11.5 nm but not for d = 6.2-6.3 nm. X-ray diffraction analysis points to a crystallographic origin of this effect. The study of closely packed assemblies of the d >= 8 nm particles observes collective (superspin) freezing that clearly appears to be governed by interparticle dipole interactions. However, the dense assemblies of the smallest particles exhibit freezing temperatures that are higher than expected from a simple (dipole) extrapolation of the corresponding temperatures found in the d >= 8 nm assemblies. It is suggested that the nature of the dominant interparticle interaction in these smaller particle assemblies is superexchange, whereby the lack of significant surface spin disorder allows this mechanism to become important at the level of interacting superspins.

    Keyword
    nanoparticles, magnetism, dipolar, superexchange
    National Category
    Nano Technology
    Identifiers
    urn:nbn:se:uu:diva-272272 (URN)10.1088/0957-4484/26/47/475703 (DOI)000366209100010 ()
    Funder
    Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
    Available from: 2016-01-18 Created: 2016-01-13 Last updated: 2017-04-07Bibliographically approved
    3. Particle size-dependent superspin glass behavior in random compacts of monodisperse maghemite nanoparticles
    Open this publication in new window or tab >>Particle size-dependent superspin glass behavior in random compacts of monodisperse maghemite nanoparticles
    Show others...
    2016 (English)In: MATERIALS RESEARCH EXPRESS, ISSN 2053-1591, Vol. 3, no 4, 045015Article in journal (Refereed) Published
    Abstract [en]

    Dense random assemblies made from highly monodisperse gamma-Fe2O3 nanoparticles with sizes ranging from 6.2 to 11.5 nm have been investigated by DC and AC magnetometry. It is found that all assemblies undergo superspin glass phase transitions. The superspin glass phase transition temperature is strongly dependent on the particle size and the nature of the interparticle interaction. However the transition from superparamagnet to superspin glass, as evidenced by the shape of the ac-susceptibility curves and the dynamic critical exponents associated with the transition, is similar in all systems.

    Keyword
    magnetic nanoparticles, maghemite, superspin glass, phase transition
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-299615 (URN)10.1088/2053-1591/3/4/045015 (DOI)000377811500016 ()
    Funder
    Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of Technology
    Available from: 2016-07-25 Created: 2016-07-25 Last updated: 2017-04-07Bibliographically approved
    4. Effects of the individual particle relaxation time on superspin glass dynamics
    Open this publication in new window or tab >>Effects of the individual particle relaxation time on superspin glass dynamics
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    2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 93, no 5, 054407Article in journal (Refereed) Published
    Abstract [en]

    The low temperature dynamic magnetic properties of two dense magnetic nanoparticle assemblies with similar superspin glass transition temperatures T-g similar to 140 K are compared. The two samples are made from batches of 6 and 8 nm monodisperse gamma-Fe2O3 nanoparticles, respectively. The properties of the individual particles are extracted from measurements on reference samples where the particles have been covered with a thick silica coating. The blocking temperatures of these dilute assemblies are found at 12.5 K for the 6 nm particles and at 35 K for the 8 nm particles, which implies different anisotropy energy barriers of the individual particles and vastly different temperature evolution of their relaxation times. The results of the measurements on the concentrated particle assemblies suggest a strong influence of the particle energy barrier on the details of the aging dynamics, memory behavior, and apparent superspin dimensionality of the particles.

    National Category
    Condensed Matter Physics Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-279564 (URN)10.1103/PhysRevB.93.054407 (DOI)000369726000001 ()
    Funder
    Swedish Research Council
    Available from: 2016-03-02 Created: 2016-03-02 Last updated: 2017-04-07Bibliographically approved
    5. Magnetic properties of nanoparticles compacts with controlled broadening of the particle size distribution
    Open this publication in new window or tab >>Magnetic properties of nanoparticles compacts with controlled broadening of the particle size distribution
    Show others...
    (English)Article in journal (Other academic) Submitted
    National Category
    Engineering and Technology Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-319714 (URN)
    Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-04-07
    6. Demagnetization effects in dense nanoparticle assemblies
    Open this publication in new window or tab >>Demagnetization effects in dense nanoparticle assemblies
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    2016 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 109, no 15, 152404Article in journal (Refereed) Published
    Abstract [en]

    We highlight the relevance of demagnetizing-field corrections in the characterization of dense magnetic nanoparticle assemblies. By an analysis that employs in-plane and out-of-plane magnetometry on cylindrical assemblies, we demonstrate the suitability of a simple analytical formula-based correction method. This allows us to identify artifacts of the demagnetizing field in temperature-dependent susceptibility curves (e.g., shoulder peaks in curves from a disordered assembly of essentially bare magnetic nanoparticles). The same analysis approach is shown to be a straightforward procedure for determining the magnetic nanoparticle packing fraction in dense, disordered assemblies.

    National Category
    Condensed Matter Physics Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-308922 (URN)10.1063/1.4964517 (DOI)000386534800031 ()
    Funder
    Swedish Research Council
    Available from: 2016-12-01 Created: 2016-12-01 Last updated: 2017-04-07Bibliographically approved
    7. Spin disorder in nanoparticles: A cautionary tale on the use of Henkel and δM plots to assess interparticle interactions
    Open this publication in new window or tab >>Spin disorder in nanoparticles: A cautionary tale on the use of Henkel and δM plots to assess interparticle interactions
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    (English)Article in journal (Other academic) Submitted
    National Category
    Engineering and Technology Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-319716 (URN)
    Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-04-07
  • Public defence: 2017-06-02 13:15 Geijersalen, Engelska parken, Uppsala
    Nordberg, Olle
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Department of Literature.
    Avkoppling och analys: Empiriska perspektiv på läsarattityder och litterär kompetens hos svenska 18-åringar2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation examines young people’s reading of fiction in the digital age, with a special focus on the aspects of attitude and competence. The literary reading of respondents in their upper teens is considered from several perspectives—especially those of the respondents themselves. The discussion is based on three larger empirical studies of the reading attitudes and practices of 18-year-olds. These studies build on and complement each other in relation to the overarching research questions through a triangulating process combining qualitative and quantitative methods. The studies are, however, freestanding and were conducted using different empirical methods.

    The first study is diachronic in that it compares national test essays on the topic of reading from the year 2000 with essays written according to the same instructions twelve years later. The main aim of this study is to reveal possible differences between the two generations in terms of attitudes and approaches to reading fiction, and to relate them to issues of literary legitimization and competence. The second study consists of a questionnaire about a short story read by the respondents, as well as about their general reading and media habits. A connection is drawn between media habits and reading frequency, on the one hand, and the results of the essay study, on the other. The respondents’ reception and understanding of the story is analyzed separately. A summary of the first two studies reveals several complex issues with contradictory patterns. The third study, which examines these issues more closely, was conducted through focus-group interviews. All three studies have been carried out among groups of pupils in the third year of upper secondary school in Sweden.

    The final part of the dissertation summarizes the results of the three studies, applying a pedagogical perspective to literature pedagogy within the subject of Swedish at the upper secondary level. This discussion points out several opportunities for literature teachers today.

     

  • Public defence: 2017-06-02 13:15 Seminar room, Belém
    Rodrigues, Debora C. M.
    Faculdade de Física, Universidade Federal do Pará.
    Electronic Structure and Atomistic Spin Dynamics of Nanostructured Materials2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The theoretical studies of several magnetic materials are presented in this thesis. To each of them, it was investigated the electronic structure, by means of density functional theory calculations, and/or magnetization dynamics, in the context of atomistic spin dynamics (ASD).  For bulk properties, we evaluate the magnon spectra of the heavy rare earths (Gd, Tb, Dy, Ho, Er, and Tm), using the exchange parameters and magnetic moments from first-principles calculations in ASD simulations. Additionally, we performed Monte Carlo simulations that nicely reproduced the qualitative trend of lowering of the critical temperatures across the series. Next, we discuss about the microscopic mechanism of the vanishingly low magnetic anisotropy of Permalloy using the concept of the orbital moment anisotropy for Fe and Ni atoms in the alloy.  Turning to surface magnetism, we discuss the use of exchange parameters computed by a noncollinear formalism for 6 monolayers of Fe on the Ir(001) substrate, in order to have a more accurate description of magnons at finite temperature and to obtain good comparison with experimental data. Besides that, we also studied surface magnons on 3 and 9 Ni monolayers on Cu(001) and Cu(111) in order to track the significant surface and/or interface effects and contrast it to properties that are fcc Ni bulk-like. Likewise, we used the Monte Carlo method to estimate the critical temperatures of Ni surfaces and compared with experimental data.  Finally, in the field of low dimensional magnetism, we present the ab-initio calculations for the electronic structure of Cr nanostructures of diverse geometries adsorbed on the Pd(111) surface, with focus on the formation of non-collinear spin configurations, either due to geometric frustration or the spin-orbit coupling provided by the substrate.

    List of papers
    1. The standard model of the rare-earths, analyzed from the Hubbard-Iapproximation
    Open this publication in new window or tab >>The standard model of the rare-earths, analyzed from the Hubbard-Iapproximation
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-267579 (URN)
    Available from: 2015-11-24 Created: 2015-11-24 Last updated: 2017-04-12
    2. Magnetic anisotropy in Permalloy: hidden quantum mechanical features
    Open this publication in new window or tab >>Magnetic anisotropy in Permalloy: hidden quantum mechanical features
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    (English)Manuscript (preprint) (Other academic)
    Keyword
    Permalloy, Orbital Anisotropy, Anisotropy Energy
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-319925 (URN)
    Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2017-04-12
    3. Finite-temperature interatomic exchange and magnon softening in Fe overlayers on Ir(001)
    Open this publication in new window or tab >>Finite-temperature interatomic exchange and magnon softening in Fe overlayers on Ir(001)
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    2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950, Vol. 94, no 1, 014413Article in journal (Refereed) Published
    Abstract [en]

    We evaluate how thermal effects soften the magnon dispersion in 6 layers of Fe(001) on top of Ir(001). We perform a systematic study considering noncollinear spin arrangement and calculate configuration-dependent exchange parameters J(ij)(nc) following the methodology described by Szilva et al. [Phys. Rev. Lett. 111, 127204 (2013)]. In addition, Monte Carlo simulations were performed in order to estimate the noncollinear spin arrangement as a function of temperature. Hence the J(ij)(nc)'s related to these configurations were calculated and used in an atomistic spin dynamics approach to evaluate the magnon spectra. Our results show good agreement with recent room-temperature measurements, and highlights how thermal effects produce magnon softening in this, and similar, systems.

    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-300459 (URN)10.1103/PhysRevB.94.014413 (DOI)000379497400007 ()
    Funder
    Swedish Research Council, 2013.0020; 2012.0031
    Available from: 2016-08-09 Created: 2016-08-09 Last updated: 2017-04-12Bibliographically approved
    4. Surface magnons and critical temperatures of Ni surfaces on Cu
    Open this publication in new window or tab >>Surface magnons and critical temperatures of Ni surfaces on Cu
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    (English)Manuscript (preprint) (Other academic)
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-319991 (URN)