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  • Public defence: 2018-08-17 13:00 Berzeliussalen, Linköping
    Lundgren, Oskar
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Psychological Resources and Risk Factors in Coronary Heart Disease: Assessment, Impact and the Influence of Mindfulness Training2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is strong evidence for the observation that psychological risk factors, such as depressive symptoms, hopelessness, and anxiety are associated with higher risk of developing coronary heart disease (CHD), and also contribute to a worse prognosis among CHD patients. Much less is known about psychological resources, such as Mastery, and their role in cardiovascular medicine. Although the current state of science about the importance of psychological factors has advanced during the last decades, the mental health status of patients is often neglected in clinical practice. The reason behind this gap is multifaceted, including unawareness of the current state of science among professionals and a lack of clear guideline, which in turn, results from a lack of evidence-based ways to address the issues. Furthermore, the measurement of psychological resources is complex and a debated topic in psychology. The aim of this thesis was to investigate: 1) If the use of inverted items in three questionnaires that measure psychological resources and risk factors represent a validity risk in the context of CHD. 2) If psychological resources and risk factors are independently associated with incidence in CHD. 3) If an eight-week course in Mindfulness-Based Stress Reduction (MBSR) is a feasible psychological intervention, as an addition to cardiac rehabilitation. 4) How CHD patients experience the practices of mindfulness and yoga in MBSR.

    In Study I and II, data from 1007 participants randomly selected from a Swedish community sample, aged 45-69 at baseline (50 % women), were analysed. To study the validity of the self-report instruments Mastery, Self-esteem and Centre for Epidemiological Studies Depression scale (CESD), subscales with only positive and negative items were created. The new subscales were evaluated against three criterion measures; cross-sectional against each other and the circulatory marker of inflammation interleukine-6 (IL-6) (concurrent construct validity); prospectively against 8-year incidence in CHD (predictive validity), and in addition, a factor analysis was used to investigate construct dimensionality. The instruments seemed to be valid measures of psychological resources and risk factors in the context of CHD risk. The new subscales showed the same associations as the original scales, except for the positive items in CES-D. However, this did not have a major influence on the full scale. In Study II a prospective analysis of the impact of psychological factors on 8-year incidence in CHD was performed. The psychological resources Mastery and Self-esteem were negatively associated with CHD, also after adjustment for nine traditional cardiovascular risk factors in Cox proportional hazard models. The protective effect of the two resources, and the increased risk of Hopelessness, remained after adjustment for depressive symptoms. In Study III and IV, a group of CHD patients with depressive symptoms (n=79) was invited to participate in MBSR as a complement to cardiac rehabilitation. Twenty-four patients started MBSR and 16 completed it. The results were compared with a reference group (n=108) of patients from the same clinic, which showed stability in psychological variables over 12 months. MBSR was appreciated by the patients and improvements in psychological risk factors (e.g., depressive symptoms), and an increase in Mastery were observed. Study IV made use of a qualitative content analysis of diary entries written by patients immediately after practice sessions throughout MBSR. Participants described difficulties, both physical and psychological, during the whole course, but as the weeks passed they more frequently described an enhanced ability to concentrate, relax and deal with distractions. From the combined findings in Study III and IV, we conclude that MBSR could be a promising complement to cardiac rehabilitation for a selection of patients.

    The overall picture, emerging from this thesis, strengthens the argument that psychological factors should be recognized and addressed in clinical practice. It also encourages further studies of how psychological resources could be built, which could inform the development of effective prevention and treatment strategies for CHD patients with psychological distress and also contribute to improved public health interventions.

    List of papers
    1. Inverted items and validity: A psychobiological evaluation of two measures of psychological resources and one depression scale
    Open this publication in new window or tab >>Inverted items and validity: A psychobiological evaluation of two measures of psychological resources and one depression scale
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    2018 (English)In: Health psychology open, ISSN 2055-1029, Vol. 5, no 1, article id 2055102918755045Article in journal (Refereed) Published
    Abstract [en]

    Psychological resources and risk factors influence risk of coronary heart disease. We evaluated whether inverted items in the Self-esteem, Mastery, and Center for Epidemiological Studies Depression scales compromise validity in the context of coronary heart disease. In a population-based sample, validity was investigated by calculating correlations with other scales (n = 1004) and interleukin-6 (n = 374), and by analyzing the relationship with 8-year coronary heart disease risk (n = 1000). Negative items did not affect the validity of the resource scales. In contrast, positive items from Center for Epidemiological Studies Depression showed no significant relationships with biological variables. However, they had no major impact on the validity of the original scale.

    Place, publisher, year, edition, pages
    Sage Publications, 2018
    Keywords
    coronary heart disease, depressiveness, interleukin-6, mastery, self-esteem, wording effect
    National Category
    General Practice
    Identifiers
    urn:nbn:se:liu:diva-146087 (URN)10.1177/2055102918755045 (DOI)29479456 (PubMedID)
    Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-06-08Bibliographically approved
    2. Psychological Resources are Associated with Reduced Incidence of Coronary Heart Disease: An 8-Year Follow-up of a Community-Based Swedish Sample
    Open this publication in new window or tab >>Psychological Resources are Associated with Reduced Incidence of Coronary Heart Disease: An 8-Year Follow-up of a Community-Based Swedish Sample
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    2014 (English)In: International Journal of Behavioral Medicine, ISSN 1070-5503, E-ISSN 1532-7558, Vol. 22, no 1, p. 77-84Article in journal (Refereed) Published
    Abstract [en]

    Background

    A large number of studies have provided clear evidence for a link between the risk of coronary heart disease and psychological risk factors. Much less attention has been given to the potential protective effect of psychological resources.

    Purpose

    The major aim of this study was to investigate the independent association between psychological resources and incidence of coronary heart disease (CHD) in an 8-year follow-up study of a Swedish community-based cohort.

    Methods

    The cohort consisted of 484 men and 497 women, aged 45–69 years at baseline. The incidence of first-time major event of CHD was analysed in relation to baseline levels of psychological resources, including mastery, self-esteem, and sense of coherence as well as psychological risk factors including cynicism and hostile affect, vital exhaustion, hopelessness, and depressive symptoms. In Cox proportional hazard models, adjustments were made for age, sex, eight traditional cardiovascular risk factors, and depressive symptoms.

    Results

    A total of 56 CHD events had occurred after the 8-year follow-up. After adjustment for age, sex, and eight traditional risk factors, a significantly decreased risk of CHD was found for mastery (HR 0.62 per SD, p = 0.003), self-esteem (HR 0.64, p = 0.004), and sense of coherence (HR 0.70, p = 0.031). An increased risk of CHD was found for vital exhaustion (HR 1.46, p = 0.014), hopelessness (HR 1.59, p = 0.003), and depressive symptoms (HR 1.45, p = 0.009). After further adjustment for depressive symptoms, significant associations remained for mastery (HR 0.67, p = 0.034), self-esteem (HR 0.69, p = 0.048), and hopelessness (HR 1.48, p = 0.023).

    Conclusions

    The psychological resources, mastery and self-esteem, showed robust protective effects on CHD, also after adjustment for established risk factors as well as depressive symptoms. In parallel, hopelessness was an independent risk factor for CHD. The results may have implications for novel approaches in preventive efforts

    Place, publisher, year, edition, pages
    Springer, 2014
    Keywords
    Mastery, Self-esteem, Sense of coherence, Hopelessness, Psychosocial, Coronary heart disease, Myocardial infarction
    National Category
    Clinical Medicine Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-108566 (URN)10.1007/s12529-014-9387-5 (DOI)000349011500009 ()24430130 (PubMedID)
    Available from: 2014-06-30 Created: 2014-06-30 Last updated: 2018-06-08Bibliographically approved
  • Public defence: 2018-08-30 10:15 Planck, Fysikhuset, Linköping
    Kalered, Emil
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Quantum chemical studies of deposition and catalytic surface reactions2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantum chemical calculations have been used to model chemical reactions in epitaxial growth of silicon carbide by chemical vapor deposition (CVD) processes and to study heterogeneous catalytic reactions for methanol synthesis. CVD is a common method to produce high-quality materials and e.g. thin films in the semiconductor industry, and one of the many usages of methanol is as a promising future renewable and sustainable energy carrier. To optimize the chemical processes it is essential to understand the reaction mechanisms. A comprehensive theoretical model for the process is therefore desired in order to be able to explore various variables that are difficult to investigate in situ. In this thesis reaction paths and reaction energies are computed using quantum chemical calculations. The quantum-chemical results can subsequently be used as input for thermodynamic, kinetic and computational fluid dynamics modelling in order to obtain data directly comparable with the experimental observations.

    For the CVD process, the effect of halogen addition to the gas mixture is studied by modelling the adsorption and diffusion of SiH2, SiCl2 and SiBr2 on the (0001̅) 4H-SiC surface. SiH2 was found to bind strongest to the surface and SiBr2 binds slightly stronger than the SiCl2 molecule. The diffusion barrier is shown to be lower for SiH2 than for SiBr2 and SiCl2 which have similar barriers. SiBr2 and SiCl2 are found to have similar physisorption energies and bind stronger than the SiH2 molecule. Gibbs free-energy calculations also indicate that the SiC surface is not fully hydrogen terminated at CVD conditions since missing-neighboring pair of surface hydrogens is found to be common. Calculations for the (0001) surface show that SiCl, SiCl2, SiHCl, SiH, and SiH2 likely adsorb on a methylene site, but the processes are thermodynamically less favorable than their reverse reactions. However, the adsorbed products may be stabilized by subsequent surface reactions to form a larger structure. The formation of these larger structures is found to be fast enough to compete with the desorption processes. Also the Gibbs free energies for adsorption of Si atoms, SiX, SiX2, and SiHX where X is F or Br are presented. Adsorption of Si atoms is shown to be the most thermodynamically favorable reaction followed by SiX, SiHX, and SiX2, X being a halide. The results in this study suggest that the major Si contributors in the SiC–CVD process are Si atoms, SiX and SiH.

    Methanol can be synthesized from gaseous carbon dioxide and hydrogen using solid metal-metal oxide mixtures acting as heterogeneous catalysts. Since a large surface area of the catalyst enhances the speed of the heterogeneous reaction, the use of nanoparticles (NP) is expected to be advantageous due to the NPs’ large area to surface ratio. The plasma-induced creation of copper NPs is investigated. One important element during particle growth is the charging process where the variation of the work function (W) with particle size is a key quantity, and the variation becomes increasingly pronounced at smaller NP sizes. The work functions are computed for a set of NP charge numbers, sizes and shapes, using copper as a case study. A derived analytical expression for W is shown to give quite accurate estimates provided that the diameter of the NP is larger than about a nanometer and that the NP has relaxed to close to a spherical shape. For smaller sizes W deviates from the approximative expression, and also depends on the charge number. Some consequences of these results for NP charging process are outlined.

    Key reaction steps in the methanol synthesis reaction mechanism using a Cu/ZrO2 nanoparticle catalyst is investigated. Two different reaction paths for conversion of CO2 to CO is studied. The two paths result in the same complete reaction 2 CO2 → 2 CO + O2 where ZrO2 (s) acts as a catalyst. The highest activation energies are significantly lower compared to that of the gas phase reaction. The presence of oxygen vacancies at the surface appear to be decisive for the catalytic process to be effective. Studies of the reaction kinetics show that when oxygen vacancies are present on the ZrO2 surface, carbon monoxide is produced within a microsecond. The IR spectra of CO2 and H2 interacting with ZrO2 and Cu under conditions that correspond to the catalyzed CH3OH production process is also studied experimentally and compared to results from the theoretical computations. Surface structures and gas-phase molecules are identified through the spectral lines by matching them to specific vibrational modes from the literature and from the new computational results. Several surface structures are verified and can be used to pin point surface structures in the reaction path. This gives important information that help decipher how the reaction mechanism of the CO2 conversion and ultimately may aid to improve the methanol synthesis process.

    List of papers
    1. Adsorption and surface diffusion of silicon growth species in silicon carbide chemical vapour deposition processes studied by quantum-chemical computations
    Open this publication in new window or tab >>Adsorption and surface diffusion of silicon growth species in silicon carbide chemical vapour deposition processes studied by quantum-chemical computations
    2013 (English)In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 132, no 12Article in journal (Refereed) Published
    Abstract [en]

    The effect chlorine addition to the gas mixture has on the surface chemistry in the chemical vapour deposition (CVD) process for silicon carbide (SiC) epitaxial layers is studied by quantum-chemical calculations of the adsorption and diffusion of SiH2 and SiCl2 on the (000-1) 4H–SiC surface. SiH2 was found to bind more strongly to the surface than SiCl2 by approximately 100 kJ mol−1 and to have a 50 kJ mol−1 lower energy barrier for diffusion on the fully hydrogen-terminated surface. On a bare SiC surface, without hydrogen termination, the SiCl2 molecule has a somewhat lower energy barrier for diffusion. SiCl2 is found to require a higher activation energy for desorption once chemisorbed, compared to the SiH2 molecule. Gibbs free energy calculations also indicate that the SiC surface may not be fully hydrogen terminated at CVD conditions since missing neighbouring pair of surface hydrogens is found to be a likely type of defect on a hydrogen-terminated SiC surface.

    Place, publisher, year, edition, pages
    Springer Verlag (Germany), 2013
    Keywords
    Quantum-chemical calculations, Density functional theory (DFT), B3LYP, Chemical vapour deposition (CVD), Silicon carbide (SiC), SiCl2, SiH2, Surface reactions, Adsorption, Reaction path, Activation energy, Diffusion, Hydrogen termination
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-100478 (URN)10.1007/s00214-013-1403-3 (DOI)000325724400001 ()
    Available from: 2013-11-08 Created: 2013-11-08 Last updated: 2018-06-19Bibliographically approved
    2. Brominated chemistry for chemical vapor deposition of electronic grade SiC
    Open this publication in new window or tab >>Brominated chemistry for chemical vapor deposition of electronic grade SiC
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    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 3, p. 793-801Article in journal (Refereed) Published
    Abstract [en]

    Chlorinated chemical vapor deposition (CVD) chemistry for growth of homoepitaxial layers of silicon carbide (SiC) has paved the way for very thick epitaxial layers in short deposition time as well as novel crystal growth processes for SiC. Here, we explore the possibility to also use a brominated chemistry for SiC CVD by using HBr as additive to the standard SiC CVD precursors. We find that brominated chemistry leads to the same high material quality and control of material properties during deposition as chlorinated chemistry and that the growth rate is on average 10 % higher for a brominated chemistry compared to chlorinated chemistry. Brominated and chlorinated SiC CVD also show very similar gas phase chemistries in thermochemical modelling. This study thus argues that brominated chemistry is a strong alternative for SiC CVD since the deposition rate can be increased with preserved material quality. The thermochemical modelling also suggest that the currently used chemical mechanism for halogenated SiC CVD might need to be revised.

    National Category
    Chemical Sciences Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-111075 (URN)10.1021/acs.chemmater.5b00074 (DOI)000349934500016 ()
    Available from: 2014-10-07 Created: 2014-10-07 Last updated: 2018-06-19Bibliographically approved
    3. Growth Mechanism of SiC Chemical Vapor Deposition: Adsorption and Surface Reactions of Active Si Species
    Open this publication in new window or tab >>Growth Mechanism of SiC Chemical Vapor Deposition: Adsorption and Surface Reactions of Active Si Species
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    2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 1, p. 648-661Article in journal (Refereed) Published
    Abstract [en]

    Silicon carbide is a wide bandgap semiconductor ideally suitable for high temperature and high power applications. An active SiC layer is usually fabricated using halide-assisted chemical vapor deposition (CVD). In this work, we use quantum chemical density functional theory (B3LYP and M06-2X) and transition state theory to study adsorptions of active Si species in the CVD process on both the Si face and the C face of 4H-SiC. We show that adsorptions of SiCl, SiCl2, SiHCl, SiH, and SiH2 on the Si face likely occur on a methylene site, CH2(ads), but the processes are thermodynamically less favorable than their reverse or desorptions. Nevertheless, the adsorbed products become stabilized with the help of subsequent surface reactions to form a larger cluster. These cluster formation reactions happen with rates that are fast enough to compete with the desorption processes. On the C face, the adsorptions likely occur on a surface site terminated by a dangling bond, *(ads), and produce the products which are thermodynamically stable. Lastly, we present the Gibbs free energies of adsorptions of Si atoms, SiX, SiX2, and SiHX, for X being F and Br. Adsorptions of Si atoms are shown to be the most thermodynamically favorable among all the species in the study. Among the halide-containing species, the Gibbs free energies (ARG) from smallest to largest are observed in the adsorptions of SiX, SiHX, and SiX2, for X being the halides. The results in this study suggest that the major Si contributors in the SiC CVD process are Si atoms, SiX (for X being the halide) and SiH.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2018
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-144885 (URN)10.1021/acs.jpcc.7b10751 (DOI)000422814200069 ()
    Note

    Funding Agencies|Swedish Foundation for Strategic Research from Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; Swedish Research Council (VR) [2016-05137_4]

    Available from: 2018-02-09 Created: 2018-02-09 Last updated: 2018-06-19
    4. On the work function and the charging of small (r <= 5 nm) nanoparticles in plasmas
    Open this publication in new window or tab >>On the work function and the charging of small (r <= 5 nm) nanoparticles in plasmas
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    2017 (English)In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 24, no 1, article id 013702Article in journal (Refereed) Published
    Abstract [en]

    The growth of nanoparticles (NPs) in plasmas is an attractive technique where improved theoretical understanding is needed for quantitative modeling. The variation of the work function W with size for small NPs, r(NP) amp;lt;= 5 nm, is a key quantity for modeling of three NP charging processes that become increasingly important at a smaller size: electron field emission, thermionic electron emission, and electron impact detachment. Here we report the theoretical values of the work function in this size range. Density functional theory is used to calculate the work functions for a set of NP charge numbers, sizes, and shapes, using copper for a case study. An analytical approximation is shown to give quite accurate work functions provided that r(NP) amp;gt; 0.4 nm, i.e., consisting of about amp;gt; 20 atoms, and provided also that the NPs have relaxed close to spherical shape. For smaller sizes, W deviates from the approximation, and also depends on the charge number. Some consequences of these results for nanoparticle charging are outlined. In particular, a decrease in W for NP radius below about 1 nm has fundamental consequences for their charge in a plasma environment, and thereby on the important processes of NP nucleation, early growth, and agglomeration. Published by AIP Publishing.

    Place, publisher, year, edition, pages
    AMER INST PHYSICS, 2017
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-136218 (URN)10.1063/1.4973443 (DOI)000395395100092 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg foundation (KAW) [2014.0276]; Swedish Research Council via the Linkoping Linneaus Environment LiLi-NFM [2008-6572]

    Available from: 2017-03-31 Created: 2017-03-31 Last updated: 2018-06-19
  • Public defence: 2018-08-31 13:00 I:101, I-huset, Linköping
    Thorsten, Anja
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Educational Sciences.
    Berättelseskrivande i skolan: Att studera, beskriva och utveckla ett kunnande2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The purpose of this thesis is to add knowledge about how the knowing of storywriting can be made teachable. This question will be addressed from two points of view: a subject-knowledge perspective and a methodological perspective. The data consists of student interviews, student stories, video-recorded lessons, field notes, meeting minutes and reflective notes collected during a Learning Study about story-writing with 9- and 10-year-old students. In a Learning Study a research group, made up of teacher researchers, investigated iteratively how the teaching can help students to develop a particular knowing. Students’ knowing, students’ learning and the instruction was analyzed using narratology, phenomenography and Variation Theory. The results show that in order to make the knowing of storywriting teachable, students need to be able to discern two main aspects: (a) seeing the story from the reader’s perspective and (b) discerning that a story is built up by problems and solutions. These two aspects consist of some other aspects, such as duration and connections between different parts of the story. The methodological issue is addressed by analyzing how teachers’ practice-based knowledge interacts with Variation Theory in a Learning Study. Polanyi’s concept of ”tacit knowledge” and other theoretical concepts of practice-based knowledge were used in the analysis. The results show that combining teachers’ experiences and Variation Theory in an iterative research model creates good conditions for a knowledge-generating process. Teachers’ practice-based knowledge affects the choice of research questions, and puts the focus on relevant parts of the data. Variation Theory brings theoretical tools to the analysis, and ensures there is a focus on the object of learning throughout the process.

    List of papers
    1. Perspektiv och problemlösning i berättelseskrivande: Vad elever behöver lära sig och hur det kan synliggöras i undervisningen
    Open this publication in new window or tab >>Perspektiv och problemlösning i berättelseskrivande: Vad elever behöver lära sig och hur det kan synliggöras i undervisningen
    2014 (Swedish)Licentiate thesis, monograph (Other academic)
    Alternative title[en]
    Perspectives and Problem Solving in Story Writing. : What pupils need to learn and how teaching can make it visible.
    Abstract [en]

    The aim of the study at hand is to generate knowledge about what pupils aged nine to ten years old need to discern in order to develop the ability to write stories with a well-developed, exciting and coherent plot, and how teaching can make it possible for the pupils to develop this ability. The theoretical framework has been Variation Theory. It is a theory of learning that focuses on how discernment of aspects affects the way we perceive our world and how variation can be used to promote learning. A basic assumption is that we learn by seeing differences, not by seeing sameness. Learning Study was used to answer the research questions. It is an interventionist approach, where the focus is on an object of learning, in this case the ability to write stories with a well-developed, exciting and coherent plot. In the research process the aim was to find out which aspects were critical for the pupils to discern in order to develop the ability, and how these could be made visible in the teaching. Together with a group of teachers, lessons were planned, implemented, evaluated and refined in an iterative process. Interview data, pupils’ texts written before and after the lessons and video recordings from the lessons were the basis of the analysis. It was found that in order for these learners to handle the object of learning, they needed to discern eight critical aspects that can be related to two different areas: (a) discerning the perspective of a reader and (b) seeing that a plot consists of several problems and solutions. The aspects were made discernible by using contrast as a pedagogical tool. The result of the study contributes to previous research by identifying and specifying what the pupils need to discern, what it means in a classroom setting and how it can be taught in a powerful way. 

    Place, publisher, year, edition, pages
    Jönköping: Högskolan för lärande och kommunikation, 2014. p. 174
    Series
    Research Reports. School of Education and Communication ; 2
    Keywords
    Story writing, writing instruction, creative writing, Variation Theory, Learning Study, primary school, berättelseskrivande, skrivundervisning, kreativt skrivande, variationsteorin, learning study, grundskolan
    National Category
    Didactics
    Identifiers
    urn:nbn:se:liu:diva-149808 (URN)9789163760297 (ISBN)
    Available from: 2018-07-25 Created: 2018-07-25 Last updated: 2018-08-01Bibliographically approved
    2. How teachers’ practice knowledge is used and challenged in a Learning Study using Variation Theory as a tool
    Open this publication in new window or tab >>How teachers’ practice knowledge is used and challenged in a Learning Study using Variation Theory as a tool
    2015 (English)In: International Journal for Lesson and Learning Studies, ISSN 2046-8253, E-ISSN 2046-8261, Vol. 4, no 3, p. 274-287Article in journal (Refereed) Published
    Abstract [en]

    Purpose– The purpose of this paper is to discuss how teachers’ practice knowledge is used as a tool in a Learning Study and how teachers’ practice knowledge is challenged by using Variation Theory as a tool in the process?Design/methodology/approach– The analysis is based on data from the research process in a Learning Study. The data consists of meeting notes of ten research meetings, field notes of the research meetings and from the enactment of the lessons, video recordings of the lessons and reflective notes after and between the meetings. The analysis is qualitative and the findings are described in themes.Findings– Teachers’ practice knowledge was used and challenged in different ways in the process. This is described in five themes. Teachers’ practice knowledge was visible in the process since it enabled relevant questions to be addressed and subtle signals from students to be taken into account. It also ensured that the activities used were suitable for the students. The theory provided a focus on the object of learning and a language to talk about teaching and learning. It also challenged teachers’ assumptions about teaching and learning and allowed them to be discussed.Originality/value– The paper addresses both teachers’ practice knowledge and Variation Theory in relation to a Learning Study. It focusses on how practice knowledge of teachers can be used and challenged in the same process. The perspective is from the inside, from a teacher researcher’s point of view.

    Place, publisher, year, edition, pages
    Emerald Group Publishing Limited, 2015
    Keywords
    Teaching, Tacit knowledge, Variation Theory, Learning study, Practice knowledge
    National Category
    Didactics
    Identifiers
    urn:nbn:se:liu:diva-139951 (URN)10.1108/IJLLS-08-2014-0030 (DOI)2-s2.0-84958948456 (Scopus ID)
    Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2018-07-26Bibliographically approved
    3. Generating knowledge in a Learning Study: from the perspective of a teacher researcher
    Open this publication in new window or tab >>Generating knowledge in a Learning Study: from the perspective of a teacher researcher
    2017 (English)In: Educational action research, ISSN 0965-0792, E-ISSN 1747-5074, Vol. 25, no 1, p. 140-154Article in journal (Refereed) Published
    Abstract [en]

    The purpose of this article is to discuss and describe how a clinical research method can be used to generate knowledge about teaching and learning. This will be addressed from a teacher researcher’s perspective, taking a conducted Learning Study as the departure. Learning Study is an interventionist, iterative and collaborative research approach, focusing on the teaching of an object of learning. The actual study was conducted by a teacher researcher leading a teacher research team in a study about story-writing in primary school. The research process and the results are discussed using four areas that are described as dichotomies by Labaree (Labaree, D.F. 2003. “The Peculiar Problems of Preparing Educational Researchers.” Educational Researcher 32 (4): 13–22). Labaree states that teacher researchers need to go from being normative, experimental, personal and particular to being analytical, theoretical, intellectual and universal. By using examples from the Learning Study, I argue that these areas do not have to be seen as dichotomies; instead they can be combined and intertwined. Thus, in a Learning Study, elements from both the teaching practice and the academic practice matter, thus enhancing the possibility that results are useful for practitioners.

    Place, publisher, year, edition, pages
    Routledge, 2017
    Keywords
    Learning Study, teacher research, clinical research, Variation Theory, writing instruction
    National Category
    Didactics
    Identifiers
    urn:nbn:se:liu:diva-139952 (URN)10.1080/09650792.2016.1141108 (DOI)000395153700011 ()2-s2.0-85011932347 (Scopus ID)
    Available from: 2017-08-22 Created: 2017-08-22 Last updated: 2018-07-26Bibliographically approved
  • Public defence: 2018-09-07 09:00 Berzeliussalen, Linköping
    Ludvigsson, Mikael
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine and Geriatrics.
    Subsyndromal depression hos äldre äldre personer2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [sv]

    Bakgrund: Subsyndromal depression (SSD) eller subklinisk depression är ett vanligt affektivt tillstånd som kan beskrivas som depressivitet under gränsen för vad som kallas syndromal eller egentlig depressiv episod. Förekomsten av SSD har rapporterats vara ungefär 10 % i populationen, eller ungefär 2-3 gånger högre än förekomsten av syndromal depression. SSD jämfört med icke-depression (ND) är associerat med en lägre aktivitetsförmåga (ADL, Activities of Daily Living), lägre kognitiv funktion, lägre subjektiv hälsa, sämre psykiska utfall och en högre dödlighet. Emellertid har flertalet studier om SSD hos äldre gjorts i åldersgruppen yngre äldre (60-80 års ålder), medan få studier har undersökt SSD hos äldre äldre personer (80+ års ålder). Eftersom många aspekter (t ex multisjukdom, skörhet, funktionsförmågor och socialt beroende) generellt förändras mellan yngre äldre och äldre äldre åldrar, så finns det ett behov av ökad kunskap om SSD hos äldre äldre. Syftet med denna avhandling var att beskriva SSD, eller det komplexa området mellan syndromal depression och normalt åldrande, hos äldre äldre personer.

    Metod: studie 1 baserades på kvalitativa intervjuer (n=27), medan studier 2-4 till stor del baserades på data från en prospektiv observationsstudie av en kohort, ”Elderly in Linköping Screening Assessment” (ELSA85). ELSA85 hade en populationsbaserad design där man följde personer från 85 års ålder i tre uppföljande mätvågor. Depressivitet mättes med 15- frågeversionen av Geriatric Depression Scale (GDS-15), som också användes för att definiera SSD i studierna.

    Resultat: Analysen av de kvalitativa intervjuerna (studie 1) resulterade i fyra teman (livet går ned och kroppen sviktar, att klara sig själv, att hänga med, och att ta en dag i taget), vilka tillsammans gav en helhetsbild av SSD i de högsta åldrarna. I en jämförelse mellan SSD, ND och syndromal depression, så skiljde sig SSD kvalitativt från syndromal depression, men däremot inte tydligt från ND. En tvärsnittsanalys av data från baslinjen av studien (studie 2) identifierade associerade faktorer till SSD bland äldre äldre personer, och enligt analysen med multipel logistisk respektive linjär regression så var det fyra domäner (sociodemografiska faktorer, sviktande fysisk funktion, neuropsykiatriska faktorer och existentiella faktorer) som var signifikant associerade med SSD.

    I en fem års longitudinell uppföljning (studie 3) visades att direkta hälso- och sjukvårdskostnader per överlevnadsmånad och person var förhöjd hos personer med SSD jämfört med ND med ett storleksförhållande 1.45 (€634 vs €436), vilket var en signifikant skillnad även när man kontrollerade för somatisk multisjukdom. I en åtta års longitudinell uppföljning visades att dödligheten var förhöjd (dödsintensitet eller Hazard ratio (HR))=1.33) för personer med SSD jämfört med ND, liksom sjuklighet avseende personlig ADL (P-ADL), instrumentell ADL (IADL), ensamhet, subjektiv hälsa, och depressivitet. Däremot var inte kognitiv snabbhet, exekutiva funktioner eller global kognitiv funktion signifikant försämrade när man hade kontrollerat för relevanta variabler.

    Slutsatser: SSD hos äldre äldre personer ser olika ut hos olika personer, och personal i hälso- och sjukvården bör vara uppmärksamma på även andra depressiva tecken förutom de klassiska symtomen i diagnosregistren. SSD hos äldre äldre är associerat med förhöjda sjukvårdskostnader, förhöjd sjuklighet och dödlighet. Med tanke på den höga förekomsten av SSD och den demografiska utvecklingen med ökande antal äldre äldre personer i samhället, så indikerar fynden behovet av att utveckla kliniska och samhälleliga strategier för att förebygga SSD och associerade negativa utfall.

    List of papers
    1. Normal Aging or Depression? A Qualitative Study on the Differences Between Subsyndromal Depression and Depression in Very Old People.
    Open this publication in new window or tab >>Normal Aging or Depression? A Qualitative Study on the Differences Between Subsyndromal Depression and Depression in Very Old People.
    2015 (English)In: The Gerontologist, ISSN 0016-9013, E-ISSN 1758-5341, Vol. 55, no 5, p. 760-769Article in journal (Refereed) Published
    Abstract [en]

    Purpose of the Study: The aim of this study was to make a qualitative comparison of experiences of being in very old people with subsyndromal depression (SSD), in relation to the experiences of very old people with syndromal depression or nondepression. Through investigation and deeper understanding of the interface between depressive disease and normal aging, clinicians might give more accurate prevention or treatment to those very old persons who need such help.

    DESIGN AND METHODS: Semistructured qualitative interviews were conducted for 27 individuals of 87-88 years of age, who were categorized in the 3 strata of nondepressive, SSD, and syndromal depression. Transcripts were analyzed using qualitative content analysis within each stratum and later with a comparison between the strata.

    RESULTS: The content analysis resulted in 4 themes in people with SSD, as defined by a self-report depression screening instrument, giving a comprehensive picture of SSD in very old people, and also showed qualitative differences between the SSD, syndromal depression, and nondepressive groups. A main finding was that SSD differs qualitatively from syndromal depression but not clearly from nondepression.

    IMPLICATIONS: The results might indicate that SSD in very old people is not related to pathology but to normal aging, even though the condition correlates with negative health parameters. Overlooking certain psychosocial aspects of living in the very old may pose a risk of both underdiagnosis and overdiagnosis in the spectrum of depressive disorders.

    Keywords
    Coping, Frailty, Healthy aging, Subthreshold depression, Successful aging
    National Category
    Psychiatry Geriatrics
    Identifiers
    urn:nbn:se:liu:diva-120848 (URN)10.1093/geront/gnt162 (DOI)000362984500006 ()24398652 (PubMedID)
    Funder
    Östergötland County Council
    Available from: 2015-08-27 Created: 2015-08-27 Last updated: 2018-07-26Bibliographically approved
    2. Markers of subsyndromal depression in very old persons.
    Open this publication in new window or tab >>Markers of subsyndromal depression in very old persons.
    2016 (English)In: International Journal of Geriatric Psychiatry, ISSN 0885-6230, E-ISSN 1099-1166, Vol. 31, no 6, p. 619-628Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: To investigate factors associated with subsyndromal depression (SSD) in very old persons, and to develop a model for prediction of SSD among very old persons.

    METHODS: A cross-sectional, population-based study was undertaken on 85-year-old persons in Sweden. Data were collected from a postal questionnaire, assessments in the participants' homes and at reception visits. Depressiveness was screened with GDS-15 (Geriatric Depression Scale), and the results were classified into three outcome categories: non-depression (ND), SSD and syndromal depression. Data were analysed with binary logistic, ordinal logistic and linear regression.

    RESULTS: With univariate logistic regression 20 factors associated with SSD were identified in very old persons, and the four hypothesized domains-sociodemographic factors, declining physical functioning, neuropsychiatric factors and existential factors-significantly related to SSD. The multivariate logistic model included seven independent factors that increase the likelihood of SSD instead of ND (lower self-perceived health, life not meaningful, problems with self-care, use of tranquilizing medication, no contact with neighbours, history of affective disorder and history of stroke). The ordinal logistic and the linear regression models resulted in seven partly different factors for predicting SSD and depressiveness, in the very old.

    CONCLUSIONS: The identified markers may help clinicians with the detection, prevention and treatment of SSD in very old persons. The findings indicate the importance of a comprehensive functional approach to diagnosing and treating depressiveness in this population, and the findings might be interpreted as offering support for the coexistence of a dimensional and a categorical view on depressive disorders.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2016
    National Category
    Geriatrics
    Identifiers
    urn:nbn:se:liu:diva-127480 (URN)10.1002/gps.4369 (DOI)000374700000009 ()26489528 (PubMedID)
    Note

    Funding agencies: County Council of Ostergotland, Sweden

    Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2018-07-26
    3. Direct Costs of Very Old Persons with Subsyndromal Depression: A 5-Year Prospective Study
    Open this publication in new window or tab >>Direct Costs of Very Old Persons with Subsyndromal Depression: A 5-Year Prospective Study
    Show others...
    2018 (English)In: The American journal of geriatric psychiatry, ISSN 1064-7481, E-ISSN 1545-7214, Vol. 26, no 7, p. 741-751Article in journal (Refereed) Published
    Abstract [en]

    Objectives

    This study aimed to compare, over a 5-year period, the prospective direct healthcare costs and service utilization of persons with subsyndromal depression (SSD) and non-depressive persons (ND), in a population of very old persons. A second aim was to develop a model that predicts direct healthcare costs in very old persons with SSD.

    Design and Setting

    A prospective population-based study was undertaken on 85-year-old persons in Sweden.

    Measurements

    Depressiveness was screened with the Geriatric Depression Scale at baseline and at 1-year follow-up, and the results were classified into ND, SSD, and syndromal depression. Data on individual healthcare costs and service use from a 5-year period were derived from national database registers. Direct costs were compared between categories using Mann-Whitney U tests, and a prediction model was identified with linear regression.

    Results

    For persons with SSD, the direct healthcare costs per month of survival exceeded those of persons with ND by a ratio 1.45 (€634 versus €436), a difference that was significant even after controlling for somatic multimorbidity. The final regression model consisted of five independent variables predicting direct healthcare costs: male sex, activities of daily living functions, loneliness, presence of SSD, and somatic multimorbidity.

    Conclusions

    SSD among very old persons is associated with increased direct healthcare costs independently of somatic multimorbidity. The associations between SSD, somatic multimorbidity, and healthcare costs in the very old need to be analyzed further in order to better guide allocation of resources in health policy.

    Place, publisher, year, edition, pages
    Elsevier, 2018
    Keywords
    Subthreshold depression; multimorbidity; oldest old; elderly; cost-of-illness; late-life depression
    National Category
    Gerontology, specialising in Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-149695 (URN)10.1016/j.jagp.2018.03.007 (DOI)000436629200003 ()29673895 (PubMedID)2-s2.0-85045544057 (Scopus ID)
    Note

    Funding Agencies|County Council of Ostergotland, Sweden

    Available from: 2018-07-24 Created: 2018-07-24 Last updated: 2018-08-14Bibliographically approved
  • Public defence: 2018-09-07 09:00 Berzeliussalen, Linköping
    Ludvigsson, Mikael
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Acute Internal Medicine and Geriatrics.
    Subsyndromal Depression in Very Old Persons2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Subsyndromal depression (SSD) or subthreshold depression is a common affective condition that can be described as depressiveness below the threshold of what is called a syndromal or a major depressive episode. The point prevalence for SSD has been reported to be about 10% in the community, or about two or three times higher than the prevalence for syndromal depression. In elderly persons, SSD compared to non-depression (ND) is associated with impaired activities of daily living, lower cognitive function, lower self-perceived health, worse psychiatric outcomes and higher mortality. However, most studies on SSD in elderly persons have been done in the young old age group (age 60-80 years), while few studies have investigated SSD in very old persons (age 80+). As many aspects (e.g. multimorbidity, frailty, functional decline and social dependence) change between the young old and the very old ages, there is a need for more knowledge about SSD in the very old. The overall aim of this doctoral thesis was to describe SSD, or the complex area between syndromal depression and normal aging, in very old persons.

    Method: Paper 1 was based on qualitative interviews (n=27), while papers 2-4 were based largely on data from a prospective observational cohort study “Elderly in Linköping Screening Assessment” (ELSA85), with a population-based design following the participants from the age of 85 in three waves of follow-up. The 15-item Geriatric Depression Scale (GDS-15) was used for measuring depressiveness and to define SSD in the studies.

    Results: The analysis of the qualitative interviews (paper 1) resulted in four themes (life curve and the body go down, to manage on one’s own, to keep up with life, and taking one day at a time), giving a comprehensive picture of SSD in very old age. In a comparison among SSD, ND and syndromal depression, SSD differed qualitatively from syndromal depression, but not clearly from ND. A cross-sectional analysis of data from baseline (paper 2) identified factors associated with SSD in very old persons, and according to analyses with multiple logistic and linear regressions, four domains (sociodemographic factors, declining physical functioning, neuropsychiatric factors, and existential factors) were significantly associated with SSD.

    A five-year longitudinal follow-up (paper 3) showed that direct healthcare costs per month of survival for persons with SSD exceeded those of persons with ND by a ratio of 1.45 (€634 vs €436), a difference that was significant even after controlling for somatic multimorbidity.

    An eight-year longitudinal follow-up (paper 4) showed that mortality was elevated (hazard ratio=1.33) for persons with SSD compared to ND, as were morbidity regarding basic ADL, IADL, loneliness, self-perceived health and depressiveness, whereas cognitive speed, executive functions and global cognitive function were not significantly impaired when adjusting for covariates.

    Conclusion: SSD in very old persons has a different presentation in different persons, and healthcare personnel should be attentive to other depressive signs beside the classical ones in the diagnostic classification registries. SSD in the very old is associated with elevated direct healthcare costs, morbidity and mortality. Considering the high prevalence of SSD and the demographic development of increasing numbers of very old people, the findings highlight the need to develop clinical and societal strategies to prevent SSD and associated negative outcomes.

    List of papers
    1. Normal Aging or Depression? A Qualitative Study on the Differences Between Subsyndromal Depression and Depression in Very Old People.
    Open this publication in new window or tab >>Normal Aging or Depression? A Qualitative Study on the Differences Between Subsyndromal Depression and Depression in Very Old People.
    2015 (English)In: The Gerontologist, ISSN 0016-9013, E-ISSN 1758-5341, Vol. 55, no 5, p. 760-769Article in journal (Refereed) Published
    Abstract [en]

    Purpose of the Study: The aim of this study was to make a qualitative comparison of experiences of being in very old people with subsyndromal depression (SSD), in relation to the experiences of very old people with syndromal depression or nondepression. Through investigation and deeper understanding of the interface between depressive disease and normal aging, clinicians might give more accurate prevention or treatment to those very old persons who need such help.

    DESIGN AND METHODS: Semistructured qualitative interviews were conducted for 27 individuals of 87-88 years of age, who were categorized in the 3 strata of nondepressive, SSD, and syndromal depression. Transcripts were analyzed using qualitative content analysis within each stratum and later with a comparison between the strata.

    RESULTS: The content analysis resulted in 4 themes in people with SSD, as defined by a self-report depression screening instrument, giving a comprehensive picture of SSD in very old people, and also showed qualitative differences between the SSD, syndromal depression, and nondepressive groups. A main finding was that SSD differs qualitatively from syndromal depression but not clearly from nondepression.

    IMPLICATIONS: The results might indicate that SSD in very old people is not related to pathology but to normal aging, even though the condition correlates with negative health parameters. Overlooking certain psychosocial aspects of living in the very old may pose a risk of both underdiagnosis and overdiagnosis in the spectrum of depressive disorders.

    Keywords
    Coping, Frailty, Healthy aging, Subthreshold depression, Successful aging
    National Category
    Psychiatry Geriatrics
    Identifiers
    urn:nbn:se:liu:diva-120848 (URN)10.1093/geront/gnt162 (DOI)000362984500006 ()24398652 (PubMedID)
    Funder
    Östergötland County Council
    Available from: 2015-08-27 Created: 2015-08-27 Last updated: 2018-07-26Bibliographically approved
    2. Markers of subsyndromal depression in very old persons.
    Open this publication in new window or tab >>Markers of subsyndromal depression in very old persons.
    2016 (English)In: International Journal of Geriatric Psychiatry, ISSN 0885-6230, E-ISSN 1099-1166, Vol. 31, no 6, p. 619-628Article in journal (Refereed) Published
    Abstract [en]

    OBJECTIVE: To investigate factors associated with subsyndromal depression (SSD) in very old persons, and to develop a model for prediction of SSD among very old persons.

    METHODS: A cross-sectional, population-based study was undertaken on 85-year-old persons in Sweden. Data were collected from a postal questionnaire, assessments in the participants' homes and at reception visits. Depressiveness was screened with GDS-15 (Geriatric Depression Scale), and the results were classified into three outcome categories: non-depression (ND), SSD and syndromal depression. Data were analysed with binary logistic, ordinal logistic and linear regression.

    RESULTS: With univariate logistic regression 20 factors associated with SSD were identified in very old persons, and the four hypothesized domains-sociodemographic factors, declining physical functioning, neuropsychiatric factors and existential factors-significantly related to SSD. The multivariate logistic model included seven independent factors that increase the likelihood of SSD instead of ND (lower self-perceived health, life not meaningful, problems with self-care, use of tranquilizing medication, no contact with neighbours, history of affective disorder and history of stroke). The ordinal logistic and the linear regression models resulted in seven partly different factors for predicting SSD and depressiveness, in the very old.

    CONCLUSIONS: The identified markers may help clinicians with the detection, prevention and treatment of SSD in very old persons. The findings indicate the importance of a comprehensive functional approach to diagnosing and treating depressiveness in this population, and the findings might be interpreted as offering support for the coexistence of a dimensional and a categorical view on depressive disorders.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2016
    National Category
    Geriatrics
    Identifiers
    urn:nbn:se:liu:diva-127480 (URN)10.1002/gps.4369 (DOI)000374700000009 ()26489528 (PubMedID)
    Note

    Funding agencies: County Council of Ostergotland, Sweden

    Available from: 2016-04-27 Created: 2016-04-27 Last updated: 2018-07-26
    3. Direct Costs of Very Old Persons with Subsyndromal Depression: A 5-Year Prospective Study
    Open this publication in new window or tab >>Direct Costs of Very Old Persons with Subsyndromal Depression: A 5-Year Prospective Study
    Show others...
    2018 (English)In: The American journal of geriatric psychiatry, ISSN 1064-7481, E-ISSN 1545-7214, Vol. 26, no 7, p. 741-751Article in journal (Refereed) Published
    Abstract [en]

    Objectives

    This study aimed to compare, over a 5-year period, the prospective direct healthcare costs and service utilization of persons with subsyndromal depression (SSD) and non-depressive persons (ND), in a population of very old persons. A second aim was to develop a model that predicts direct healthcare costs in very old persons with SSD.

    Design and Setting

    A prospective population-based study was undertaken on 85-year-old persons in Sweden.

    Measurements

    Depressiveness was screened with the Geriatric Depression Scale at baseline and at 1-year follow-up, and the results were classified into ND, SSD, and syndromal depression. Data on individual healthcare costs and service use from a 5-year period were derived from national database registers. Direct costs were compared between categories using Mann-Whitney U tests, and a prediction model was identified with linear regression.

    Results

    For persons with SSD, the direct healthcare costs per month of survival exceeded those of persons with ND by a ratio 1.45 (€634 versus €436), a difference that was significant even after controlling for somatic multimorbidity. The final regression model consisted of five independent variables predicting direct healthcare costs: male sex, activities of daily living functions, loneliness, presence of SSD, and somatic multimorbidity.

    Conclusions

    SSD among very old persons is associated with increased direct healthcare costs independently of somatic multimorbidity. The associations between SSD, somatic multimorbidity, and healthcare costs in the very old need to be analyzed further in order to better guide allocation of resources in health policy.

    Place, publisher, year, edition, pages
    Elsevier, 2018
    Keywords
    Subthreshold depression; multimorbidity; oldest old; elderly; cost-of-illness; late-life depression
    National Category
    Gerontology, specialising in Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-149695 (URN)10.1016/j.jagp.2018.03.007 (DOI)000436629200003 ()29673895 (PubMedID)2-s2.0-85045544057 (Scopus ID)
    Note

    Funding Agencies|County Council of Ostergotland, Sweden

    Available from: 2018-07-24 Created: 2018-07-24 Last updated: 2018-08-14Bibliographically approved
  • Public defence: 2018-09-07 13:15 Ada Lovelace, B-huset, Linköping
    Ovrén, Hannes
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering.
    Continuous Models for Cameras and Inertial Sensors2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Using images to reconstruct the world in three dimensions is a classical computer vision task. Some examples of applications where this is useful are autonomous mapping and navigation, urban planning, and special effects in movies. One common approach to 3D reconstruction is ”structure from motion” where a scene is imaged multiple times from different positions, e.g. by moving the camera. However, in a twist of irony, many structure from motion methods work best when the camera is stationary while the image is captured. This is because the motion of the camera can cause distortions in the image that lead to worse image measurements, and thus a worse reconstruction. One such distortion common to all cameras is motion blur, while another is connected to the use of an electronic rolling shutter. Instead of capturing all pixels of the image at once, a camera with a rolling shutter captures the image row by row. If the camera is moving while the image is captured the rolling shutter causes non-rigid distortions in the image that, unless handled, can severely impact the reconstruction quality.

    This thesis studies methods to robustly perform 3D reconstruction in the case of a moving camera. To do so, the proposed methods make use of an inertial measurement unit (IMU). The IMU measures the angular velocities and linear accelerations of the camera, and these can be used to estimate the trajectory of the camera over time. Knowledge of the camera motion can then be used to correct for the distortions caused by the rolling shutter. Another benefit of an IMU is that it can provide measurements also in situations when a camera can not, e.g. because of excessive motion blur, or absence of scene structure.

    To use a camera together with an IMU, the camera-IMU system must be jointly calibrated. The relationship between their respective coordinate frames need to be established, and their timings need to be synchronized. This thesis shows how to automatically perform this calibration and synchronization, without requiring e.g. calibration objects or special motion patterns.

    In standard structure from motion, the camera trajectory is modeled as discrete poses, with one pose per image. Switching instead to a formulation with a continuous-time camera trajectory provides a natural way to handle rolling shutter distortions, and also to incorporate inertial measurements. To model the continuous-time trajectory, many authors have used splines. The ability for a spline-based trajectory to model the real motion depends on the density of its spline knots. Choosing a too smooth spline results in approximation errors. This thesis proposes a method to estimate the spline approximation error, and use it to better balance camera and IMU measurements, when used in a sensor fusion framework. Also proposed is a way to automatically decide how dense the spline needs to be to achieve a good reconstruction.

    Another approach to reconstruct a 3D scene is to use a camera that directly measures depth. Some depth cameras, like the well-known Microsoft Kinect, are susceptible to the same rolling shutter effects as normal cameras. This thesis quantifies the effect of the rolling shutter distortion on 3D reconstruction, depending on the amount of motion. It is also shown that a better 3D model is obtained if the depth images are corrected using inertial measurements.

    List of papers
    1. Improving RGB-D Scene Reconstruction using Rolling Shutter Rectification
    Open this publication in new window or tab >>Improving RGB-D Scene Reconstruction using Rolling Shutter Rectification
    2015 (English)In: New Development in Robot Vision / [ed] Yu Sun, Aman Behal & Chi-Kit Ronald Chung, Springer Berlin/Heidelberg, 2015, p. 55-71Chapter in book (Refereed)
    Abstract [en]

    Scene reconstruction, i.e. the process of creating a 3D representation (mesh) of some real world scene, has recently become easier with the advent of cheap RGB-D sensors (e.g. the Microsoft Kinect).

    Many such sensors use rolling shutter cameras, which produce geometrically distorted images when they are moving. To mitigate these rolling shutter distortions we propose a method that uses an attached gyroscope to rectify the depth scans.We also present a simple scheme to calibrate the relative pose and time synchronization between the gyro and a rolling shutter RGB-D sensor.

    For scene reconstruction we use the Kinect Fusion algorithm to produce meshes. We create meshes from both raw and rectified depth scans, and these are then compared to a ground truth mesh. The types of motion we investigate are: pan, tilt and wobble (shaking) motions.

    As our method relies on gyroscope readings, the amount of computations required is negligible compared to the cost of running Kinect Fusion.

    This chapter is an extension of a paper at the IEEE Workshop on Robot Vision [10]. Compared to that paper, we have improved the rectification to also correct for lens distortion, and use a coarse-to-fine search to find the time shift more quicky.We have extended our experiments to also investigate the effects of lens distortion, and to use more accurate ground truth. The experiments demonstrate that correction of rolling shutter effects yields a larger improvement of the 3D model than correction for lens distortion.

    Place, publisher, year, edition, pages
    Springer Berlin/Heidelberg, 2015
    Series
    Cognitive Systems Monographs, ISSN 1867-4925 ; 23
    National Category
    Computer Vision and Robotics (Autonomous Systems)
    Identifiers
    urn:nbn:se:liu:diva-114344 (URN)10.1007/978-3-662-43859-6_4 (DOI)978-3-662-43858-9 (ISBN)978-3-662-43859-6 (ISBN)
    Projects
    Learnable Camera Motion Models
    Available from: 2015-02-19 Created: 2015-02-19 Last updated: 2018-06-19Bibliographically approved
    2. Gyroscope-based video stabilisation with auto-calibration
    Open this publication in new window or tab >>Gyroscope-based video stabilisation with auto-calibration
    2015 (English)In: 2015 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA), 2015, p. 2090-2097Conference paper, Published paper (Refereed)
    Abstract [en]

    We propose a technique for joint calibration of a wide-angle rolling shutter camera (e.g. a GoPro) and an externally mounted gyroscope. The calibrated parameters are time scaling and offset, relative pose between gyroscope and camera, and gyroscope bias. The parameters are found using non-linear least squares minimisation using the symmetric transfer error as cost function. The primary contribution is methods for robust initialisation of the relative pose and time offset, which are essential for convergence. We also introduce a robust error norm to handle outliers. This results in a technique that works with general video content and does not require any specific setup or calibration patterns. We apply our method to stabilisation of videos recorded by a rolling shutter camera, with a rigidly attached gyroscope. After recording, the gyroscope and camera are jointly calibrated using the recorded video itself. The recorded video can then be stabilised using the calibrated parameters. We evaluate the technique on video sequences with varying difficulty and motion frequency content. The experiments demonstrate that our method can be used to produce high quality stabilised videos even under difficult conditions, and that the proposed initialisation is shown to end up within the basin of attraction. We also show that a residual based on the symmetric transfer error is more accurate than residuals based on the recently proposed epipolar plane normal coplanarity constraint.

    Series
    IEEE International Conference on Robotics and Automation ICRA, ISSN 1050-4729
    Keywords
    Calibration, Cameras, Cost function, Gyroscopes, Robustness, Synchronization
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-120182 (URN)10.1109/ICRA.2015.7139474 (DOI)000370974902014 ()978-1-4799-6922-7; 978-1-4799-6923-4 (ISBN)
    Conference
    2015 IEEE International Conference on Robotics and Automation (ICRA), Seattle, WA, USA, 26-30 May, 2015
    Projects
    LCMMVPS
    Funder
    Swedish Research Council, 2014-5928Swedish Foundation for Strategic Research , IIS11-0081
    Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2018-06-19Bibliographically approved
    3. Spline Error Weighting for Robust Visual-Inertial Fusion
    Open this publication in new window or tab >>Spline Error Weighting for Robust Visual-Inertial Fusion
    2018 (English)Conference paper, Oral presentation only (Refereed)
    Abstract [en]

    In this paper we derive and test a probability-based weighting that can balance residuals of different types in spline fitting. In contrast to previous formulations, the proposed spline error weighting scheme also incorporates a prediction of the approximation error of the spline fit. We demonstrate the effectiveness of the prediction in a synthetic experiment, and apply it to visual-inertial fusion on rolling shutter cameras. This results in a method that can estimate 3D structure with metric scale on generic first-person videos. We also propose a quality measure for spline fitting, that can be used to automatically select the knot spacing. Experiments verify that the obtained trajectory quality corresponds well with the requested quality. Finally, by linearly scaling the weights, we show that the proposed spline error weighting minimizes the estimation errors on real sequences, in terms of scale and end-point errors.

    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-149495 (URN)
    Conference
    The IEEE Conference on Computer Vision and Pattern Recognition (CVPR), June 18-22, 2018, Salt Lake City, USA
    Funder
    Swedish Research Council, 2014-5928Swedish Research Council, 2014-6227
    Available from: 2018-07-03 Created: 2018-07-03 Last updated: 2018-08-02Bibliographically approved
  • Public defence: 2018-09-14 10:15 ACAS, A-huset, Linköping
    Larsson, Ulf
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system, University of Gävle, Gävle, Sweden..
    On the performance of stratified ventilation2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    People nowadays spend most of their time indoors, for example in their homes, cars, in trains, at work, etc. In Sweden, the energy demand in the built environment is a growing issue. The building sector accounts for 40% of total energy use and 15% of total CO2 emissions, and around one-third of the energy use in the world is related to providing a healthy and good comfort indoors. To achieve acceptable indoor climates new designs for the ventilation systems have been proposed in recent decades, among them stratified ventilation systems.

    Stratified ventilation is a concept that often allows good performance for both indoor air quality and thermal comfort. Stratified ventilation systems are effective in reducing cross contamination, since there is virtually no mixing in the space; the temperature and the pollutant concentration increase linearly from the heat source with the height of the occupied zone. There are many different ventilation supply devices using the stratified principle, such as displacement supply device (DSD), impinging jet supply device (IJSD) and wall confluent jet supply device (WCJSD).

    The main aim of this thesis is to analyze and compare different supply devices based on stratified ventilation, with different setups, related to thermal indoor climate, energy efficiency and ventilation efficiency. The ultimate goal is to contribute to an increased understanding of how ventilation systems with stratified supply devices perform.

    Two scientific methods have mainly been used in this thesis, i.e., experimental and numerical investigations. For numerical experiments the CFD (Computational Fluid Dynamics) code ANSYS and FIDAP have been used. Experimental studies have been performed with thermocouples, Hot-Wire Anemometry (HWA) and Hot-Sphere Anemometry, thermal comfort measurement equipment and tracer gas measurement equipment.

    This thesis mainly focuses on three research questions: Interaction between a supply device based on stratified ventilation and downdraft from windows; Flow behavior, energy performance and air change effectiveness for different supply devices based on stratified ventilation; and Thermal comfort for different supply devices based on stratified ventilation.

    Research question one showed that the arrangement of displacement supply device and window in cold climate has significant effect on the flow pattern below the window. Different supply airflow rates have an effect on both the velocity and the temperature of the downdraft. In this case the velocity decreased by approximately 9.5% and the temperature in the downdraft decreased 0.5°C when the flowrate from the supply device increased from 10 to 15 l/s.

    Research question two showed that airflow patterns between different air supply systems were essentially related to characteristics of air supply devices, such as the type, configuration and position, as well as air supply velocities and momentum. For WCJSD, IJSD and DSD, positions of heat sources (such as occupant, computers, lights and external heat sources) played an important role in formation of the room airflow pattern. One interesting observation is that the temperature in the occupied zone is lower and a more stratified temperature field implies a more efficient heat removal by a stratified air supply device. The results revealed that the lowest temperature in the occupied zone was achieved for DSD, but with IJSD and WCJSD slightly warmer, while the system with a mixing supply device (MSD) showed a much higher temperature. The results confirm that air change effectiveness (ACE) for the DSD, WCJSD and IJSD is close to each other. However, MSD shows lower ACE in all the present papers than IJSD, WCJSD and DSD.

    Research question three showed that ventilation systems with stratified supply devices in almost all of the studied cases showed an acceptable level for predicted percentage dissatisfied (PPD), predicted mean vote (PMV) and percentage dissatisfied due to draft (DR). If comparing ventilation systems, using IJSD, WCJSD or DSD with MSD always showed thermal comfort better or at the same level.

    List of papers
    1. Thermal analysis of super insulated windows (numerical and experimental investigations)
    Open this publication in new window or tab >>Thermal analysis of super insulated windows (numerical and experimental investigations)
    1999 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 29, no 2, p. 121-128Article in journal (Refereed) Published
    Abstract [en]

    Windows are crucial for people's experience of the indoor climate, especially in the Nordic countries with cold climate and short days during the winter. This paper reports the first results from an ongoing research project focused on an improved integration of windows with the indoor air climate and people's perception of the windows. The thermal performance of a well-insulated window has been investigated both numerically and experimentally in a full scale test room. The window under consideration is a low-emissive triple-glazing window with two closed spaces filled with the inert gas krypton. An oxidised metal with low emissivity factor coats one pane in each space. Experimental and numerical investigations on the thermal performance of the window have been conducted for different winter cases. Temperature data obtained by direct temperature measurement using thermocouples and through numerical analysis are presented. The heat transfer through a window construction depends on three mechanisms i.e., conduction, convection and radiation. In this paper the convection-conducting mechanisms have been closely investigated. The numerical predictions agree well with the results from the measurements.

    Keywords
    Thermal analysis, Low-emissive triple-glazing window, Super insulated windows
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-149820 (URN)10.1016/S0378-7788(98)00041-3 (DOI)
    Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26
    2. Experimental investigation of downdraught from well-insulated windows
    Open this publication in new window or tab >>Experimental investigation of downdraught from well-insulated windows
    2002 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 37, no 11, p. 1073-1082Article in journal (Refereed) Published
    Abstract [en]

    Since the climate in the Nordic countries is cold for several months a year, windows are crucial in building envelopes. The current trend to reduce heat losses by building components has resulted in many modifications to window design in order to improve thermal performance and the indoor climate. Improvements in window construction have resulted in a higher surface temperature on the inner pane and considerably lower downdraught, which in turn has created an opportunity for the unconventional design of the heating and ventilation systems. The impetus for this paper is to experimentally investigate the effect of thermal performance, window bay and displacement ventilation on the downdraught. The measurements show that the use of well-insulated windows, besides lowering energy consumption, gives rise to a higher quality of indoor climate. The results show a considerably reduced velocity and turbulent intensity by employing a well-insulated window instead of a conventional one. The influence of the window bay on the downdraught is also shown in the paper. © 2002 Elsevier Science Ltd. All rights reserved.

    Keywords
    Displacement ventilation, Downdraught, Indoor climate, Measurement, Well-insulated window
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-46864 (URN)10.1016/S0360-1323(01)00110-X (DOI)
    Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2018-07-26
    3. Numerical investigation of ventilation performance of different air supply devices in an office environment
    Open this publication in new window or tab >>Numerical investigation of ventilation performance of different air supply devices in an office environment
    2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 90, p. 37-50Article in journal (Refereed) Published
    Abstract [en]

    Abstract The aim of this study was to compare ventilation performance of four different air supply devices in an office environment with respect to thermal comfort, ventilation efficiency and energy-saving potential, by performing numerical simulations. The devices have the acronyms: Mixing supply device (MSD), Wall confluent jets supply device (WCJSD), Impinging jet supply device (IJSD) and Displacement supply device (DSD). Comparisons were made under identical set-up conditions, as well as at the same occupied zone temperature of about 24.2 °C achieved by adding different heat loads and using different air-flow rates. Energy-saving potential was addressed based on the air-flow rate and the related fan power required for obtaining a similar occupied zone temperature for each device. Results showed that the WCJSD and IJSD could provide an acceptable thermal environment while removing excess heat more efficiently than the MSD, as it combined the positive effects of both mixing and stratification principles. This benefit also meant that this devices required less fan power than the MSD for obtaining equivalent occupant zone temperature. The DSD showed a superior performance on heat removal, air exchange efficiency and energy saving to all other devices, but it had difficulties in providing acceptable vertical temperature gradient between the ankle and neck levels for a standing person.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keywords
    Ventilation performance, Air supply devices, Thermal comfort, Energy-saving potential
    National Category
    Energy Engineering
    Identifiers
    urn:nbn:se:liu:diva-117439 (URN)10.1016/j.buildenv.2015.03.021 (DOI)000356189000004 ()
    Note

    Formas [242-2008-835]; KK Foundation [2007/0289]; University of Gavle (Gavle, Sweden); Linkoping University (Linkoping, Sweden)

    Available from: 2015-04-27 Created: 2015-04-27 Last updated: 2018-07-26Bibliographically approved
    4. An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office
    Open this publication in new window or tab >>An experimental investigation of the flow and comfort parameters for under-floor, confluent jets and mixing ventilation systems in an open-plan office
    Show others...
    2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 48-60Article in journal (Refereed) Published
    Abstract [en]

    There is a new trend to convert the workplaces from individual office rooms to open offices for motivating money saving and better communication. With such a shift the ability of existing ventilation systems in meeting the new requirements is a challenging question for researchers. The available options could have an impact on workers' health in terms of providing acceptable levels of thermalcomfort and indoor air quality. Thus, this experimental investigation focuses on the performances of three different air distribution systems in an open-plan office space. The investigated systems were: mixing ventilation with ceiling-mounted inlets, confluent jets ventilation and underfloor air distribution with straight and curved vanes. Although this represents a small part of our more extensiveexperimental investigation, the results show that all the purposed stratified ventilation systems (CJV and UFAD) were more or less behaving as mixing systems with some tendency for displacement effects. Nevertheless, it is known that the mixing systems have a stable flow pattern but has the disadvantage of mixing contaminated air with the fresh supplied air which may produce lower performance and in worst cases occupants' illness. For the open-plan office we studied here, it will be shown that the new systems are capable of performing better than the conventional mixing systems. As expected, the higher air exchange efficiency in combination with lower local mean age of air for corner-mounted CJV and floor-mounted UFAD grills systems indicates that these systems are suitable for open-plan offices and are to be favored over conventional mixing systems.

    Keywords
    Open office, Mixing ventilation (MV), Underfloor air distribution (UFAD), Confluent jets ventilation (CJV)
    National Category
    Building Technologies
    Identifiers
    urn:nbn:se:liu:diva-149816 (URN)10.1016/j.buildenv.2015.04.019 (DOI)000358807800006 ()2-s2.0-84929492281 (Scopus ID)
    Funder
    VINNOVA
    Available from: 2015-05-16 Created: 2018-07-26 Last updated: 2018-07-26
    5. Comparison of ventilation performance of three different air supply devices: a measurement study
    Open this publication in new window or tab >>Comparison of ventilation performance of three different air supply devices: a measurement study
    2017 (English)In: The International Journal of Ventilation, ISSN 1473-3315, E-ISSN 2044-4044, Vol. 16, no 3, p. 244-254Article in journal (Refereed) Published
    Abstract [en]

    People today spend a significant part of their time in an indoor environment, whether it be home, school, vehicle or workplace. This has put greater demands on indoor environment, in terms of both air quality and thermal comfort. The main objective of building ventilation is to take care of pollutants and lower their concentration, but it is also used to cool or heat indoor air. The aim of this paper was to study the behavior of three different ventilation supply devices, i.e. mixing supply device, displacement supply device and confluent jet supply device, in an office room. Different cases have been studied experimentally with different airflow rates, supply air temperature and supply devices. The results shows that mostly that we can expect, but the results show a very small difference in ventilation efficiency between the different systems and in theory there should be a larger difference.

    Place, publisher, year, edition, pages
    Taylor & Francis, 2017
    Keywords
    Mixing ventilation; displacement ventilation; confluent jet ventilation; measurement; air exchange efficiency
    National Category
    Building Technologies
    Identifiers
    urn:nbn:se:liu:diva-139644 (URN)10.1080/14733315.2017.1299519 (DOI)000406118900008 ()
    Available from: 2017-08-09 Created: 2017-08-09 Last updated: 2018-07-26
    6. Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation
    Open this publication in new window or tab >>Numerical investigation of Air Change Effectiveness in an Office Room with Impinging Jet Ventilation
    2018 (English)In: Proceedings of the 4th international Conference on Building Energy & Environment / [ed] K. Inthavong*, C.P Cheung, G. Yeoh, J.Y. Tu, Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia , 2018, p. 641-646, article id 218Conference paper, Published paper (Refereed)
    Abstract [en]

    Providing occupant comfort and health with minimum use of energy is the ultimate purpose of heating, ventilating and air conditioning systems. This paper presents the air-change effectiveness (ACE) within a typical office room using impinging jet ventilation (IJV ) in combination with chilled ceiling (CC) under different heat loads ranging from 6.5 - 51 W per square meter floor area. In this study, a validated CFD model based on the v2f turbulence model is used for the prediction of air flow pattern and ACE. The interaction effect of chilled ceiling and heat sources results in a complex flow with air circulation. The thermal plumes and air circulation in the room result in a variation of ACE within the room but also close to the occupant. For all studied cases, ACE is above 1.2 close to the occupants, indicating that IJV is more energy efficient than mixing ventilation.

    Place, publisher, year, edition, pages
    Melbourne: Conference On Building Energy & Environment - COBEE2018, Melbourne Australia, 2018
    Keywords
    Impinging jet ventilation
    National Category
    Energy Engineering
    Identifiers
    urn:nbn:se:liu:diva-149819 (URN)978-0-646-98213-7 (ISBN)
    Conference
    COBEE2018, 4th international Conference on Building Energy & Environment,5-9 February 2018, Melbourne, Australia
    Available from: 2018-05-15 Created: 2018-07-26 Last updated: 2018-07-26
    7. Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices - a measurement study
    Open this publication in new window or tab >>Comparison of the thermal comfort and ventilation effectiveness in an office room with three different ventilation supply devices - a measurement study
    2018 (English)In: Proceedings of14th International Conference of Roomvent & Ventilation, Aalto University , 2018, p. 187-192Conference paper, Published paper (Refereed)
    Abstract [en]

    People spend a significant part of their time in an indoor environment, whether at home, school or workplace. The aim of this paper is to experimentally study the ventilation effectiveness (mean age of air, MAA) and thermal comfort (PMV and PPD) of three different ventilation supply devices, i.e., mixing supply device (MSD), displacement supply device (DSD) and wall confluent jet supply device (WCJSD) in an office room.

    This paper is based on analysis from full-scale measurements performed in a laboratory at University of Gävle. The size of the room corresponds to a typical office module for one person. The test room has dimensions of 4.2 x 3.0 x 2.4 m with a volume of 31.24 m3, with the size of the room corresponding to a typical office. Different heat sources are used to simulate the office environment, which corresponds to 31.75 W/m2.

    The PMV and PPD are comparable to MSD, WCJSD and DSD as it turns out that MSD has poorer comfort than DSD and WCJSD. DSD and WCJSD have more or less the same thermal comfort performance. When comparing the local mean age of air (MAA) for the studied supply devices, the air is significantly much younger for the DSD and WCJSD than for MSD.  

    Place, publisher, year, edition, pages
    Aalto University, 2018
    Keywords
    Mixing ventilation, Displacement ventilation, Wall confluent jet ventilation, Thermal comfort, Ventilation effectiveness
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-149822 (URN)9789525236484 (ISBN)
    Conference
    Roomvent & Ventilation 2018, June 2-5 2018,Aalto University, Espoo, Finland
    Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26
  • Public defence: 2018-09-21 10:15 ACAS, A-huset, Linköping
    Kienzler, Mario
    Linköping University, Department of Management and Engineering, Industrial Economics. Linköping University, Faculty of Science & Engineering.
    Micro-foundations of value-based pricing and selling2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Enabling customer value creation is central to marketing theory and practice. Yet, doing so does not ensure that supplier firms profit from it. Value-based pricing and selling come with the prospect of translating customer value creation into greater profits for suppliers. However, despite sustained interest, only a limited number of firms emphasize value-based pricing and selling. Existing research has highlighted organizational challenges as potential reasons. Unfortunately, this focus on organizational challenges obscures the role of individuals within organizations (i.e., its micro-foundations), such as the fact that managers and salespeople determine and realize prices. The purpose of this thesis is thus to describe and analyze the micro-foundations of value-based pricing and selling in business markets.

    The thesis’ conceptual framework introduces bounded rationality and heterogeneity—two overlooked forces—to investigate the affective, cognitive, and motivational micro-foundations of value-based pricing and selling. The thesis’ empirical foundation consists of five papers that investigate the microfoundations suggested by the framework.

    The findings indicate that research would benefit from a wider variety of research approaches. Currently, insights into micro-foundations are lacking, in part due to the focus on research designs and theories aimed at the organizational level; experimental designs and theories from psychology would allow amendments to prior research. Furthermore, individual rationality and individual differences play a role. In this regard, managers’ cognitive biases impact upon the extent to which firms focus on value-based pricing. Moreover, price presentation impacts managers’ value perception and purchase intention. The findings also suggest that managers’ personalities and salespeople’s experience and learning orientation are important individual differences affecting the emphasis on valuebased pricing and selling. Consequently, affective, cognitive and motivational micro-foundations—arising due to bounded rationality and heterogeneity— explain some of the challenges associated with value-based pricing and selling.

    This thesis contributes with insights into several micro-foundations affecting value-based pricing and selling. In so doing, the thesis belongs to a growing stream of research that is shifting the focus from organizational processes to the individual foundations of value-based pricing and selling. The thesis also provides suggestions on how managers can use micro-foundations to the advantage of their firms.

    List of papers
    1. Pricing strategy: A review of 22 years of marketing research
    Open this publication in new window or tab >>Pricing strategy: A review of 22 years of marketing research
    2017 (English)In: Journal of Business Research, ISSN 0148-2963, E-ISSN 1873-7978, Vol. 78, p. 101-110Article, review/survey (Refereed) Published
    Abstract [en]

    This article investigates the development and current state of pricing strategy research by undertaking a content analysis of 515 articles published in leading academic journals between 1995 and 2016. The results suggest several developments in research focus and methodology; recent research has focused more strongly on services and applies more rigorous research designs. The results also indicate a persistent focus on consumer markets and economic theories, as well as an increasing consideration of demand-side respondents, at the expense of supply-side respondents. An important feature of this review is a set of actionable takeaways, with both theoretical and methodological implications for pricing strategy research.

    Place, publisher, year, edition, pages
    Elsevier, 2017
    Keywords
    Pricing strategy; Literature review; Content analysis; Marketing; Takeaways
    National Category
    Business Administration
    Identifiers
    urn:nbn:se:liu:diva-137345 (URN)10.1016/j.jbusres.2017.05.005 (DOI)000405053800010 ()
    Funder
    Torsten Söderbergs stiftelse, E24/14
    Note

    Funding agencies: Torsten Soderbergs Stiftelse, Sweden [E24/14]

    Available from: 2017-05-13 Created: 2017-05-13 Last updated: 2018-06-21Bibliographically approved
    2. Does managerial personality influence pricing practices under uncertainty?
    Open this publication in new window or tab >>Does managerial personality influence pricing practices under uncertainty?
    2017 (English)In: Journal of Product & Brand Management, ISSN 1061-0421, Vol. 26, no 7, p. 771-784Article in journal (Refereed) Published
    Abstract [en]

    Purpose - While marketing and management research suggests that managers individual characteristics influence pricing decisions, the influence of personality traits in this context remains unclear. This study aims to explore the relationship between the five basic personality traits of the five-factor model (extraversion, conscientiousness, openness to experience, agreeableness and neuroticism) and three basic pricing practices (value-, competition- and cost-informed). Design/methodology/approach - On the basis of a non-experimental decision-making scenario, the analysis examines the pricing decisions of 57 managers in relation to a new business service. Findings - The results suggest that managers conscientiousness and openness to experience are positively related to preference for value- informed pricing. Similarly, managers agreeableness is positively related to preference for competition- informed pricing and managers openness to experience and agreeableness are positively related to preference for cost-informed pricing. Research limitations/implications - The cross-sectional study design does not support causal inference, and the modest sample size may limit the external validity of the findings. Practical implications - By increasing awareness of the influence of personality on pricing preferences, the findings are of relevance to managers who are directly involved in pricing decisions. Additionally, the findings are informative for managers who must assign responsibility for pricing authority within firms. Originality/value - This empirical exploration of the relationship between certain personality traits and specific pricing practices contributes to the literature on psychological aspects of pricing theory by showing how managerial personality influences pricing preferences under uncertainty.

    Place, publisher, year, edition, pages
    EMERALD GROUP PUBLISHING LTD, 2017
    Keywords
    Personality; Pricing; PLS modelling; Judgement and decision making
    National Category
    Business Administration
    Identifiers
    urn:nbn:se:liu:diva-143961 (URN)10.1108/JPBM-11-2016-1352 (DOI)000417505100009 ()
    Note

    Funding Agencies|Torsten Soderbergs Stiftelse, Sweden [E24/14]

    Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-06-21
    3. Value-based pricing and cognitive biases: An overview for business markets
    Open this publication in new window or tab >>Value-based pricing and cognitive biases: An overview for business markets
    2018 (English)In: Industrial Marketing Management, ISSN 0019-8501, E-ISSN 1873-2062, Vol. 68, p. 86-94Article in journal (Refereed) Published
    Abstract [en]

    To investigate how cognitive biases inhibit value-based pricing practices among managers in business markets, this article considers five different cognitive biases—perceived lack of control, herding, fixed-pie bias, ambiguity aversion, and egocentric fairness bias—and their effects on value-based pricing. Despite recent calls for more research on the psychological aspects of pricing, few studies have focused on business markets. Drawing on research in psychology and marketing for its theoretical foundation, this overview extends the limited body of existing research. The article's key contribution is to explain how psychological challenges affect value-based pricing practices, with implications and suggestions for further research.

    Place, publisher, year, edition, pages
    Elsevier, 2018
    Keywords
    Value-based pricing; Cognitive bias; Debiasing; Business market; Managerial decision-making
    National Category
    Business Administration Applied Psychology
    Identifiers
    urn:nbn:se:liu:diva-141951 (URN)10.1016/j.indmarman.2017.09.028 (DOI)000424310200008 ()2-s2.0-85031322039 (Scopus ID)
    Funder
    Torsten Söderbergs stiftelse, E24/14
    Available from: 2017-10-14 Created: 2017-10-14 Last updated: 2018-06-21Bibliographically approved
  • Public defence: 2018-09-21 13:00 Belladonna, Hus 511, Linköping
    Eckhardt, Martin
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Emergency Medicine.
    The Bumpy Road to Universal Health Coverage: Access to Primary and Emergency Care in Rural Tropical Ecuador2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: By the turn of the new millennium 84% of families in rural coastal Ecuador had difficulties to access health services. A health reform some years earlier to improve this situation had not been implemented. In 2001, the non-governmental organization (NGO) Foundation Human Nature together with a rural population established a primary health care center in North-Western Ecuador. A public private partnership with the Ministry of Public Health was formed. Services depended on out-ofpocket payments, restricting the poor’s access to care. In order to increase access to primary and emergency care, Foundation Human Nature planned to establish a community-based health insurance. In the meantime, a major health reform was initiated by a new government in 2008. It aimed at universal health coverage, providing qualitative services for all based on primary health care, while ensuring protection from financial hardship. The aims of this thesis were to appraise the feasibility of community- based health insurance in Ecuador; to study how rural stakeholders perceived the 2008 reform and its effects on rural health services; to explore the local population’s perception of the NGO in service delivery; and to measure the scope and describe the nature of perceived emergencies, the related health care seeking behavior and health expenditure.

    Methods: Quantitative and qualitative methods were applied to tackle the research objectives. Data collection for the health insurance study and the study of perceived emergencies was carried out through cross-sectional household surveys. For each of the studies 210 households were sampled with two-stage cluster sampling. Structured questionnaires were used with on the spot household interviews. Focus group discussions with local stakeholders were performed to explore their perceived effects of the 2008 health reform. The population’s perception of the NGO was also studied through focus group discussions, which were complemented by key-informant interviews with local stakeholders. Inductive qualitative content analysis, focusing on the manifest content was applied.

    Results: 69% of interviewees were willing to join the presented community- based health insurance scheme for 30 US$ per household and year. Attitudes towards the scheme were positive and 92% of interviewees stated they would increase their health service utilization with affiliation. The implementation of the 2008 health reform was perceived as topdown, lacking communication. However, the reform’s effects were mainly perceived as positive with free medical attendance and drugs. Increased service utilization was described as leading to a relative shortage of drugs and appointments. Access problems for remote dwellers were found, who were described of having to seek private care, also in emergencies. The NGO and its services were perceived positively by the population due to health care improvements in the region. The structure of the public private partnership was unclear, leading to dissatisfaction. Community participation was found to be rather weak. Perceived emergencies occurred to at least 90/1,000 inhabitants in the past year. Fever, traumatic injury and abdominal pain were the most frequent chief complaints. The first contacted providers in 57% of all cases were private for-profit providers, including traditional healers. Public health services treated one third of all cases. Health expenditure was found to be high and catastrophic health expenditure occurred in 24% of all cases.

    Conclusions: Prior to the 2008 reform community-based health insurance was found to be feasible in the study region. This financing instrument may have a role in the post-reform system, to cover services that the government does not yet sufficiently provide. The effects of the 2008 reform were mainly perceived positively, but an adjustment of the system is needed to improve the relative lack of drugs and appointments, especially for remote dwellers. Free health services may not be sufficient to reach universal health coverage for patients with perceived emergencies. Changes in public emergency departments and improved financial protection for emergency patients may improve the situation. The NGO’s role was perceived positively by the population. A lack of communication about the public private partnership and relatively weak community participation restricted the NGO’s full potential and should be improved.

    List of papers
    1. Feasibility of community-based health insurance in rural tropical Ecuador
    Open this publication in new window or tab >>Feasibility of community-based health insurance in rural tropical Ecuador
    2011 (English)In: REVISTA PANAMERICANA DE SALUD PUBLICA-PAN AMERICAN JOURNAL OF PUBLIC HEALTH, ISSN 1020-4989, Vol. 29, no 3, p. 177-184Article in journal (Refereed) Published
    Abstract [en]

    Objective. The main objective of this study was to assess peoples willingness to join a community-based health insurance (CHI) model in El Paramo, a rural area in Ecuador, and to determine factors influencing this willingness. A second objective was to identify peoples understanding and attitudes toward the presented CHI model. Methods. A cross-sectional survey was carried out using a structured questionnaire. Of an estimated 829 households, 210 were randomly selected by two-stage cluster sampling. Attitudes toward the scheme were assessed. Information on factors possibly influencing willingness to join was collected and related to the willingness to join. To gain an insight into a respondents possible ability to pay, health care expenditure on the last illness episode was assessed. Feasibility was defined as at least 50% of household heads willing to join the scheme. Results. Willingness to join the CHI model for US$30 per year was 69.3%. With affiliation, 92.2% of interviewees stated that they would visit the local health facility more often. Willingness to join was found to be negatively associated with education. Other variables showed no significant association with willingness to join. The study showed a positive attitude toward the CHI scheme. Substantial health care expenditures on the last illness episode were documented. Conclusions. The investigation concludes that CHI in the study region is feasible. However, enrollments are likely to be lower than the stated willingness to join. Still, a CHI scheme should present an interesting financing alternative in rural areas where services are scarce and difficult to sustain.

    Place, publisher, year, edition, pages
    Organizacion Panamericana de la Salud, 2011
    Keywords
    Health insurance, feasibility studies, primary health care, Ecuador
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-68013 (URN)000289364100005 ()
    Available from: 2011-05-06 Created: 2011-05-06 Last updated: 2018-07-26
    2. Collaboration between non-governmental organizations and public services in health - a qualitative case study from rural Ecuador
    Open this publication in new window or tab >>Collaboration between non-governmental organizations and public services in health - a qualitative case study from rural Ecuador
    Show others...
    2016 (English)In: Global Health Action, ISSN 1654-9716, E-ISSN 1654-9880, Vol. 9, article id 32237Article in journal (Refereed) Published
    Abstract [en]

    Background: Non-governmental organizations (NGOs) have a key role in improving health in low-and middle-income countries. Their work needs to be synergistic, complementary to public services, and rooted in community mobilization and collective action. The study explores how an NGO and its health services are perceived by the population that it serves, and how it can contribute to reducing barriers to care. Design: A qualitative exploratory study was conducted in remote Ecuador, characterized by its widespread poverty and lack of official governance. An international NGO collaborated closely with the public services to deliver preventative and curative health services. Data were collected using focus group discussions and semistructured interviews with purposively sampled community members, healthcare personnel, and community health workers based on their links to the health services. Conventional qualitative content analysis was used, focusing on manifest content. Results: Emerging themes relate to the public private partnership (PPP), the NGO and its services, and community participation. The population perceives the NGO positively, linking it to healthcare improvements. Their priority is to get services, irrespective of the providers structure. The presence of an NGO in the operation may contribute to unrealistic expectations of health services, affecting perceptions of the latter negatively. Conclusions: To avoid unrealistic expectations and dissatisfaction, and to increase and sustain the populations trust in the organization, an NGO should operate in a manner that is as integrated as possible within the existing structure. The NGO should work close to the population it serves, with services anchored in the community. PPP parties should develop a common platform with joint messages to the target population on the providers structure, and regarding partners roles and responsibilities. Interaction between the population and the providers on service content and their expectations is key to positive outcomes of PPP operations.

    Place, publisher, year, edition, pages
    CO-ACTION PUBLISHING, 2016
    Keywords
    community participation; healthcare services; perception; primary healthcare; public private partnership
    National Category
    Health Care Service and Management, Health Policy and Services and Health Economy
    Identifiers
    urn:nbn:se:liu:diva-134110 (URN)10.3402/gha.v9.32237 (DOI)000390858600001 ()27852423 (PubMedID)
    Note

    Funding Agencies|Karolinska Institutet; Linkoping University; Ecuador

    Available from: 2017-01-22 Created: 2017-01-22 Last updated: 2018-07-26
  • Public defence: 2018-10-01 10:15 BL32, B-huset, Linköping
    Shuaib, Budor
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Ghostpeakons2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis we study peakons (peaked solitons), a class of solutions which occur in certain wave equations, such as the Camassa–Holm shallow water equation and its mathematical relatives, the Degasperis–Procesi, Novikov and Geng– Xue equations. These four non-linear partial differential equations are all integrable systems in the sense of having Lax pairs, infinitely many conservation laws, and multipeakon solutions given by explicitly known formulas.

    In the first paper, we develop a method which uses so-called ghostpeakons (peakons with amplitude zero) to find explicit formulas for the characteristic curves associated with the multipeakon solutions of the Camassa–Holm, Degasperis– Procesi and Novikov equations.

    In the second paper, we use the ghostpeakon method to derive explicit formulas for arbitrary multipeakon solutions of the two-componentGeng–Xue equation. The general case involves many inequivalent peakons configurations, depending on the order in which the peakons occur in the two components of the solution, and previously the solution was known only in the so-called interlacing case where the peakons lie alternatingly in one component and in the other. To obtain the solution formulas for an arbitrary configuration, we introduce auxiliary peakons to make the configuration interlacing. By taking suitable limits, we then drive the amplitudes of the auxiliary peakons to zero, leaving the solution formulas for the remaining ordinary peakons.