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  • Public defence: 2017-05-30 10:15 Hörsal C:3, Linköping
    Nyagahakwa, Venuste
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Families of Sets Without the Baire Property2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The family of sets with the Baire property of a topological space X, i.e., sets which differ from open sets by meager sets, has different nice properties, like being closed under countable unions and differences. On the other hand, the family of sets without the Baire property of X is, in general, not closed under finite unions and intersections. This thesis focuses on the algebraic set-theoretic aspect of the families of sets without the Baire property which are not empty. It is composed of an introduction and five papers.

    In the first paper, we prove that the family of all subsets of ℝ of the form (C \ M) ∪ N, where C is a finite union of Vitali sets and M, N are meager, is closed under finite unions. It consists of sets without the Baire property and it is invariant under translations of ℝ. The results are extended to the space ℝn for n ≥ 2 and to products of ℝn with finite powers of the Sorgenfrey line.

    In the second paper, we suggest a way to build a countable decomposition  of a topological space X which has an open subset homeomorphic to (ℝn, τ), n ≥ 1, where τ is some admissible extension of the Euclidean topology, such that the union of each non-empty proper subfamily of  does not have the Baire property in X. In the case when X is a separable metrizable manifold of finite dimension, each element of  can be chosen dense and zero-dimensional.

    In the third paper, we develop a theory of semigroups of sets with respect to the union of sets. The theory is applied to Vitali selectors of ℝ to construct diverse abelian semigroups of sets without the Baire property. It is shown that in the family of such semigroups there is no element which contains all others. This leads to a supersemigroup of sets without the Baire property which contains all these semigroups and which is invariant under translations of ℝ. All the considered semigroups are enlarged by the use of meager sets, and the construction is extended to Euclidean spaces ℝn for n ≥ 2.

    In the fourth paper, we consider the family V1(Q) of all finite unions of Vitali selectors of a topological group G having a countable dense subgroup Q. It is shown that the collection  is a base for a topology τ(Q) on G. The space (G, τ (Q)) is T1, not Hausdorff and hyperconnected. It is proved that if Q1 and Q2 are countable dense subgroups of G such that Q1 ⊆ Q2 and the factor group Q2/Q1 is infinite (resp. finite) then τ(Q1 τ(Q2) (resp. τ (Q1) ⊆ τ (Q2)). Nevertheless, we prove that all spaces constructed in this manner are homeomorphic.

    In the fifth paper, we investigate the relationship (inclusion or equality) between the families of sets with the Baire property for different topologies on the same underlying set. We also present some applications of the local function defined by the Euclidean topology on R and the ideal of meager sets there.

    List of papers
    1. On the families of sets without the Baire property generated by the Vitali sets
    Open this publication in new window or tab >>On the families of sets without the Baire property generated by the Vitali sets
    2011 (English)In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 3, no 2, 100-107 p.Article in journal (Refereed) Published
    Abstract [en]

    Let A be the family of all meager sets of the real line ℝ, V be the family of all Vitali sets of ℝ, V1be the family of all finite unions of elements of V and V2 = {(C \ A1) ∪ A2: C ∈ V1; A1, A2 ∈ A}. We show that the families VV1, V2 are invariant under translations of ℝ, and V1, V2 are abelian semigroups with the respect to the operation of union of sets. Moreover, V ⊂ V1 ⊂ V2 and V2consists of zero-dimensional sets without the Baire property. Then we extend the results above to the Euclidean spaces ℝnn ≥ 2, and their products with the finite powers of the Sorgenfrey line.

    Place, publisher, year, edition, pages
    Springer, 2011
    Keyword
    Vitali set of ℝn, Baire property, nonmeasurable set in the sense of Lebesgue, Sorgenfrey line
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-136258 (URN)10.1134/S2070046611020026 (DOI)
    Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2017-05-09Bibliographically approved
    2. ON COUNTABLE FAMILIES OF SETS WITHOUT THE BAIRE PROPERTY
    Open this publication in new window or tab >>ON COUNTABLE FAMILIES OF SETS WITHOUT THE BAIRE PROPERTY
    2013 (English)In: Colloquium Mathematicum, ISSN 0010-1354, E-ISSN 1730-6302, Vol. 133, no 2, 179-187 p.Article in journal (Refereed) Published
    Abstract [en]

    We suggest a method of constructing decompositions of a topological space X having an open subset homeomorphic to the space (R-n , tau), where n is an integer greater than= 1 and tau is any admissible extension of the Euclidean topology of R-n (in particular, X can be a finite-dimensional separable metrizable manifold), into a countable family F of sets (dense in X and zero-dimensional in the case of manifolds) such that the union of each non-empty proper subfamily of F does not have the Baire property in X.

    Place, publisher, year, edition, pages
    Polskiej Akademii Nauk, Instytut Matematyczny (Polish Academy of Sciences, Institute of Mathematics), 2013
    Keyword
    Vitali set; Baire property; admissible extension of a topology
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-103315 (URN)10.4064/cm133-2-4 (DOI)000328741300004 ()
    Available from: 2014-01-16 Created: 2014-01-16 Last updated: 2017-05-04
    3. THE ALGEBRA OF SEMIGROUPS OF SETS
    Open this publication in new window or tab >>THE ALGEBRA OF SEMIGROUPS OF SETS
    2015 (English)In: Mathematica Scandinavica, ISSN 0025-5521, Vol. 116, no 2, 161-170 p.Article in journal (Refereed) Published
    Abstract [en]

    We study the algebra of semigroups of sets (i.e. families of sets closed under finite unions) and its applications. For each n greater than 1 we produce two finite nested families of pairwise different semigroups of sets consisting of subsets of R" without the Baire property.

    Place, publisher, year, edition, pages
    MATEMATISK INST, 2015
    National Category
    Algebra and Logic
    Identifiers
    urn:nbn:se:liu:diva-120758 (URN)000358751500001 ()
    Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2017-05-04
    4. Vitali selectors in topological groups and related semigroups of sets
    Open this publication in new window or tab >>Vitali selectors in topological groups and related semigroups of sets
    2015 (English)In: Questions Answers in General Topology, ISSN 0918-4732, Vol. 33, no 2, 93-102 p.Article in journal (Refereed) Published
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-136253 (URN)
    Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2017-05-04Bibliographically approved
  • Public defence: 2017-05-31 10:15 Ada Lovelace, Hus B, Ingång 25, Linköping
    Nielsen, Isak
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Structure-Exploiting Numerical Algorithms for Optimal Control2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Numerical algorithms for efficiently solving optimal control problems are important for commonly used advanced control strategies, such as model predictive control (MPC), but can also be useful for advanced estimation techniques, such as moving horizon estimation (MHE). In MPC, the control input is computed by solving a constrained finite-time optimal control (CFTOC) problem on-line, and in MHE the estimated states are obtained by solving an optimization problem that often can be formulated as a CFTOC problem. Common types of optimization methods for solving CFTOC problems are interior-point (IP) methods, sequential quadratic programming (SQP) methods and active-set (AS) methods. In these types of methods, the main computational effort is often the computation of the second-order search directions. This boils down to solving a sequence of systems of equations that correspond to unconstrained finite-time optimal control (UFTOC) problems. Hence, high-performing second-order methods for CFTOC problems rely on efficient numerical algorithms for solving UFTOC problems. Developing such algorithms is one of the main focuses in this thesis. When the solution to a CFTOC problem is computed using an AS type method, the aforementioned system of equations is only changed by a low-rank modification between two AS iterations. In this thesis, it is shown how to exploit these structured modifications while still exploiting structure in the UFTOC problem using the Riccati recursion. Furthermore, direct (non-iterative) parallel algorithms for computing the search directions in IP, SQP and AS methods are proposed in the thesis. These algorithms exploit, and retain, the sparse structure of the UFTOC problem such that no dense system of equations needs to be solved serially as in many other algorithms. The proposed algorithms can be applied recursively to obtain logarithmic computational complexity growth in the prediction horizon length. For the case with linear MPC problems, an alternative approach to solving the CFTOC problem on-line is to use multiparametric quadratic programming (mp-QP), where the corresponding CFTOC problem can be solved explicitly off-line. This is referred to as explicit MPC. One of the main limitations with mp-QP is the amount of memory that is required to store the parametric solution. In this thesis, an algorithm for decreasing the required amount of memory is proposed. The aim is to make mp-QP and explicit MPC more useful in practical applications, such as embedded systems with limited memory resources. The proposed algorithm exploits the structure from the QP problem in the parametric solution in order to reduce the memory footprint of general mp-QP solutions, and in particular, of explicit MPC solutions. The algorithm can be used directly in mp-QP solvers, or as a post-processing step to an existing solution.

  • Public defence: 2017-06-01 10:00 Berzeliussalen, Linköping
    Wiss, Johanna
    Linköping University, Department of Medical and Health Sciences, Division of Health Care Analysis. Linköping University, Faculty of Medicine and Health Sciences.
    Healthcare Priority Setting and Rare Diseases: What Matters When Reimbursing Orphan Drugs2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rarity of a disease can give rise to challenges that differ from conventional diseases. For example, rarity hampers research and development of new drugs, and patients with severe, rare diseases have limited access to qualified treatments. When drugs are available, clinical evidence has higher uncertainty and the drugs can be very expensive. When setting priorities in the healthcare sector, treatments aimed at patients with rare diseases, so called orphan drugs, have become a source of concern. Orphan drugs seldom show solid evidence of effectiveness or cost-effectiveness. Still, treatments for rare disease patients, available on the European market, has increased rapidly since the adoption of a regulation offering incentives for research and development of orphan drugs. The question arises as to whether the publicly funded health care system should provide such expensive treatments, and if so, to what extent.

    This doctoral thesis aims to investigate healthcare priority setting and rare diseases in the context of orphan drug reimbursement. Priority setting for orphan drugs is located at the intersection of economic, ethical and psychological perspectives. This intersection is explored by studying the public’s view on the relevance of rarity when setting priorities for orphan drugs, and by examining how orphan drugs are managed when making reimbursement decisions in practice. Papers I and II in this thesis employ quantitative, experimental methods in order to investigate preferences for prioritising rare diseases, and the extent to which psychological factors influence such preferences. Papers III and IV employ qualitative methods to further explore what factors (apart from rarity) influence priority-setting decisions for orphan drugs, as well as how decisions regarding orphan drugs are made in practice in England, France, the Netherlands, Norway and Sweden. Combining quantitative and qualitative methods has provided a more comprehensive understanding of the topic explored in the thesis, and the methods have complemented each other.

    Paper I shows that there is no general preference for giving higher priority to rare disease patients when allocating resources between rare and common disease patients. However, results show that preferences for treating the rare patients are malleable to a set of psychological factors, in particular “proportion dominance”. Paper II shows that the identifiability of an individual has no, or a negative, influence on the share of respondents choosing to allocate resources to him/her (compared to a nonidentified individual). Paper III confirms that rarity per se is not seen as a factor that should influence priority-setting decisions (i.e. accept a greater willingness to pay for orphan drugs), however, other factors such as disease severity, treatment effect and whether there are treatment alternatives were seen as relevant for consideration. Paper IV explores the challenges with and solutions for orphan drug reimbursement, as perceived by different actors in five European countries. Perceived challenges are related to the components involved when making reimbursement decisions, to the reimbursement system, and to the acceptance of the final decision. Solutions are either specific for orphan drugs, or general measures that can be used for orphan drugs as well as for other drugs.

    In conclusion, priority setting for orphan drugs is complex and requires particular attention from decision makers. There are many factors to consider when making reimbursement decisions for orphan drugs. The consequences of a decision are potentially severe (both for rare disease patients and for common disease patients, depending on the decision) and psychological factors can potentially influence decisions.

    List of papers
    1. Prioritizing Rare Diseases: Psychological Effects Influencing Medical Decision Making
    Open this publication in new window or tab >>Prioritizing Rare Diseases: Psychological Effects Influencing Medical Decision Making
    2017 (English)In: Medical decision making, ISSN 0272-989X, E-ISSN 1552-681XArticle in journal, Letter (Refereed) Epub ahead of print
    Abstract [en]

    Background. Measuring societal preferences for rarity has been proposed to determine whether paying pre- mium prices for orphan drugs is acceptable. Objective. To investigate societal preferences for rarity and how psychological factors affect such preferences. Method. A postal survey containing resource allocation dilemmas involving patients with a rare disease and patients with a common disease, equal in severity, was sent out to a randomly selected sample of the population in Sweden (return rate 42.3%, n = 1270). Results. Overall, we found no evidence of a general preference for prioritizing treat- ment of patients with rare disease patients over those with common diseases. When treatment costs were equal, most respondents (42.7%) were indifferent between the choice options. Preferences for prioritizing patients with common diseases over those with rare diseases were more frequently displayed (33.3% v. 23.9%). This tendency was, as expected, amplified when the rare disease was costlier to treat. The share of respondents choosing to treat patients with rare diseases increased when present- ing the patients in need of treatment in relative rather than absolute terms (proportion dominance). Surprisingly, identifiability did not increase preferences for rarity. Instead, identifying the patient with a rare disease made respondents more willing to prioritize the patients with common diseases. Respondents’ levels of education were significantly associated with choice—the lower the level of education, the more likely they were to choose the rare option. Conclusions. We find no support for the existence of a general preference for rarity when setting health care priorities. Psychological effects, especially proportion dominance, are likely to play an important role when pre- ferences for rarity are expressed.  

    Place, publisher, year, edition, pages
    Sage Publications, 2017
    Keyword
    orphan drugs; rare diseases; priority setting; societal preferences; survey; resource allocation; proportion dominance; identifiability.
    National Category
    Economics Health Care Service and Management, Health Policy and Services and Health Economy Psychology (excluding Applied Psychology)
    Identifiers
    urn:nbn:se:liu:diva-134647 (URN)10.1177/0272989X17691744 (DOI)
    Funder
    Ragnar Söderbergs stiftelseMarianne and Marcus Wallenberg Foundation
    Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2017-04-27Bibliographically approved
    2. The influence of identifiability and singularity in moral decision making
    Open this publication in new window or tab >>The influence of identifiability and singularity in moral decision making
    Show others...
    2015 (English)In: Judgment and decision making, ISSN 1930-2975, E-ISSN 1930-2975, Vol. 10, no 5, 492-502 p.Article in journal (Refereed) Published
    Abstract [en]

    There is an increased willingness to help identified individuals rather than non-identified, and the effect of identifiability is mainly present when a single individual rather than a group is presented. However, identifiability and singularity effects have thus far not been manipulated orthogonally. The present research uses a joint evaluation approach to examine the relative contribution of identifiability and singularity in moral decision-making reflecting conflicting values between deontology and consequentialism. As in trolley dilemmas subjects could either choose to stay with the default option, i.e., giving a potentially life-saving vaccine to a single child, or to actively choose to deny the single child the vaccine in favor of five other children. Identifiability of the single child and the group of children was varied between-subjects in a 2x2 factorial design. In total 1,232 subjects from Sweden and the United States participated in three separate experiments. Across all treatments, in all three experiments, 32.6% of the subjects chose to stay with the deontological default option instead of actively choosing to maximize benefits. Results show that identifiability does not always have a positive effect on decisions in allocation dilemmas. For single targets, identifiability had a negative or no effect in two out of three experiments, while for the group of targets identifiability had a more stable positive effect on subjects’ willingness to allocate vaccines. When the effect of identifiability was negative, process data showed that this effect was mediated by emotional reactance. Hence, the results show that the influence of identifiability is more complex than it has been previously portrayed in the literature on charitable giving. 

    Keyword
    identifiable victim effect, singularity effect, resource allocation, trolley dilemma, moral judgment, decision making, charitable giving
    National Category
    Applied Psychology
    Identifiers
    urn:nbn:se:liu:diva-122128 (URN)000362067700009 ()
    Note

    Funding text: Ragnar Soderberg Foundation; U.S. National Science Foundation [SES-1227729, SES-1427414]

    Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2017-04-27Bibliographically approved
  • Public defence: 2017-06-01 10:00 Nobel BL32, B-huset, Linköping
    Kurujyibwami, Celestin
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Admissible transformations and the group classification of Schrödinger equations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    We study admissible transformations and solve group classification problems for various classes of linear and nonlinear Schrödinger equations with an arbitrary number n of space variables.

    The aim of the thesis is twofold. The first is the construction of the new theory of uniform seminormalized classes of differential equations and its application to solving group classification problems for these classes. Point transformations connecting two equations (source and target) from the class under study may have special properties of semi-normalization. This makes the group classification of that class using the algebraic method more involved. To extend this method we introduce the new notion of uniformly semi-normalized classes. Various types of uniform semi-normalization are studied: with respect to the corresponding equivalence group, with respect to a proper subgroup of the equivalence group as well as the corresponding types of weak uniform semi-normalization. An important kind of uniform semi-normalization is given by classes of homogeneous linear differential equations, which we call uniform semi-normalization with respect to linear superposition of solutions.

    The class of linear Schrödinger equations with complex potentials is of this type and its group classification can be effectively carried out within the framework of the uniform semi-normalization. Computing the equivalence groupoid and the equivalence group of this class, we show that it is uniformly seminormalized with respect to linear superposition of solutions. This allow us to apply the version of the algebraic method for uniformly semi-normalized classes and to reduce the group classification of this class to the classification of appropriate subalgebras of its equivalence algebra. To single out the classification cases, integers that are invariant under equivalence transformations are introduced. The complete group classification of linear Schrödinger equations is carried out for the cases n = 1 and n = 2.

    The second aim is to study group classification problem for classes of generalized nonlinear Schrödinger equations which are not uniformly semi-normalized. We find their equivalence groupoids and their equivalence groups and then conclude whether these classes are normalized or not. The most appealing classes are the class of nonlinear Schrödinger equations with potentials and modular nonlinearities and the class of generalized Schrödinger equations with complex-valued and, in general, coefficients of Laplacian term. Both these classes are not normalized. The first is partitioned into an infinite number of disjoint normalized subclasses of three kinds: logarithmic nonlinearity, power nonlinearity and general modular nonlinearity. The properties of the Lie invariance algebras of equations from each subclass are studied for arbitrary space dimension n, and the complete group classification is carried out for each subclass in dimension (1+2). The second class is successively reduced into subclasses until we reach the subclass of (1+1)-dimensional linear Schrödinger equations with variable mass, which also turns out to be non-normalized. We prove that this class is mapped by a family of point transformations to the class of (1+1)-dimensional linear Schrödinger equations with unique constant mass.

    List of papers
    1. Equivalence groupoid for (1+2)-dimensional linear Schrodinger equations with complex potentials
    Open this publication in new window or tab >>Equivalence groupoid for (1+2)-dimensional linear Schrodinger equations with complex potentials
    2015 (English)In: SEVENTH INTERNATIONAL WORKSHOP: GROUP ANALYSIS OF DIFFERENTIAL EQUATIONS AND INTEGRABLE SYSTEMS (GADEISVII), IOP Publishing: Conference Series / Institute of Physics (IoP) , 2015, Vol. 621, no UNSP 012008, UNSP 012008- p.Conference paper (Refereed)
    Abstract [en]

    We describe admissible point transformations in the class of (1+2)-dimensional linear Schrodinger equations with complex potentials. We prove that any point transformation connecting two equations from this class is the composition of a linear superposition transformation of the corresponding initial equation and an equivalence transformation of the class. This shows that the class under study is semi-normalized.

    Place, publisher, year, edition, pages
    IOP Publishing: Conference Series / Institute of Physics (IoP), 2015
    Series
    Journal of Physics Conference Series, ISSN 1742-6588 ; 621
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-120668 (URN)10.1088/1742-6596/621/1/012008 (DOI)000357939100008 ()
    Conference
    7th International Workshop on Group Analysis of Differential Equations and Integrable Systems (GADEIS)
    Available from: 2015-08-20 Created: 2015-08-20 Last updated: 2017-05-15
  • Public defence: 2017-06-01 13:00 Belladonna, Linköping
    Jonsson, Åsa
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    How to create and analyze a Heart Failure Registry with emphasis on Anemia and Quality of Life2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background and aims

    Heart failure (HF) is a major cause of serious morbidity and death in the population and one of the leading medical causes of hospitalization among people older than 60 years. The aim of this thesis was to describe how to create and how to analyze a Heart Failure Registry with emphasis on Anemia and Quality of Life. (Paper I) We described the creation of the Swedish Heart Failure Registry (SwedeHF) as an instrument, which may help to optimize the handling of HF patients and show how the registry can be used to improve the management of patients with HF. (Paper II) In order to show how to analyze a HF registry we investigated the prevalence of anemia, its predictors, and its association with mortality and morbidity in a large cohort of unselected patients with HFrEF included in the SwedeHF, and to explore if there are subgroups of HF patients identifying high--‐risk patients in need of treatment. (Paper III) In order to show another way of analyzing a HF registry we assessed the prevalence of, associations with, and prognostic impact of anemia in patients with HFmrEF and HFpEF. (Paper IV) Finally we examined the usefulness of EQ--‐ 5D as a measure of patient--‐reported outcomes among HF patients using different analytical models and data from the SwedeHF, and comparing results about HRQoL for patients with HFpEF and HFrEF.

    Methods

    An observational study based on the SwedeHF database, consisting of about 70 variables, was undertaken to describe how a registry is created and can be used (Paper I). One comorbidity (anemia) was applied to different types of HF patients, HFrEF (EF <40%) (II) and HFmrEF (EF 40--‐49% ) or HFpEF (> 50%) (III) analyzing the data with different statistical methods. The usefulness of EQ--‐5D as measure of patient--‐ reported outcomes was studied and the results about HRQoL were compared for patients with HFpEF and HFrEF (IV).

    Results

    In the first paper (Paper I) we showed how to create a HF registry and presented some characteristics of the patients included, however not adjusted since this was not the purpose of the study. In the second paper (Paper II) we studied anemia in patients with HFrEF and found that the prevalence of anemia in HFrEF were 34 % and the most important independent predictors were higher age, male gender and renal dysfunction. One--‐year survival was 75 % with anemia vs. 81 % without (p<0,001). In the matched cohort after propensity score the hazard ratio associated with anemia was for all--‐cause death 1.34. Anemia was associated with greater risk with lower age, male gender, EF 30--‐39%, and NYHA--‐class I--‐II. In the third paper (Paper III) we studied anemia in other types of HF patients and found that the prevalence in the overall cohort in patients with EF > 40% was 42 %, in HFmrEF 38 % and in HFpEF (45%). Independent associations with anemia were HFpEF, male sex, higher age, worse New York Heart Association class and renal function, systolic blood pressure <100 mmHg, heart rate ≥70 bpm, diabetes, and absence of atrial fibrillation. One--‐year survival with vs. without anemia was 74% vs. 89% in HFmrEF and 71% vs. 84% in HFpEF (p<0.001 for all). Thus very similar results in paper II and III but in different types of HF patients. In the fourth paper (Paper IV) we studied the usefulness of EQ--‐5D in two groups of patients with HF (HFpEF and HFrEF)) and found that the mean EQ--‐5D index showed small reductions in both groups at follow--‐up. The patients in the HFpEF group reported worsening in all five dimensions, while those in the HFrEF group reported worsening in only three. The Paretian classification showed that 24% of the patients in the HFpEF group and 34% of those in the HFrEF group reported overall improvement while 43% and 39% reported overall worsening. Multiple logistic regressions showed that treatment in a cardiology clinic affected outcome in the HFrEF group but not in the HFpEF group (Paper IV).

    Conclusions

    The SwedeHF is a valuable tool for improving the management of patients with HF, since it enables participating centers to focus on their own potential for improving diagnoses and medical treatment, through the online reports (Paper I). Anemia is associated with higher age, male gender and renal dysfunction and increased risk of mortality and morbidity (II, III). The influence of anemia on mortality was significantly greater in younger patients in men and in those with more stable HF (Paper II, III). The usefulness of EQ--‐5D is dependent on the analytical method used. While the index showed minor differences between groups, analyses of specific dimensions showed different patterns of change in the two groups of patients (HFpEF and HFrEF). The Paretian classification identified subgroups that improved or worsened, and can therefore help to identify needs for improvement in health services (Paper IV).

    List of papers
    1. Heart failure registry: a valuable tool for improving the management of patients with heart failure
    Open this publication in new window or tab >>Heart failure registry: a valuable tool for improving the management of patients with heart failure
    2010 (English)In: European Journal of Heart Failure, ISSN 1388-9842, Vol. 12, no 1, 25-31 p.Article in journal (Refereed) Published
    Abstract [en]

    Guidelines on how to diagnose and treat patients with heart failure (HF) are published regularly. However, many patients do not fulfil the diagnostic criteria and are not treated with recommended drugs. The Swedish Heart Failure Registry (S-HFR) is an instrument which may help to optimize the handling of HF patients. The S-HFR is an Internet-based registry in which participating centres (units) can record details of their HF patients directly online and transfer data from standardized forms or from computerized patient documentation. Up to December 2007, 16 117 patients from 78 units had been included in the S-HFR. Of these, 10 229 patients had been followed for at least 1 year, and 2133 deaths were recorded. Online reports from the registry showed that electrocardiograms were available for 97% of the patients. Sinus rhythm was found in 51% of patients and atrial fibrillation in 38%. Echocardiography was performed in 83% of the patients. Overall, 77% of patients were treated with angiotensin converting enzyme inhibitors or angiotensin II receptor blockers, 80% were on beta-blockers, 34% on aldosterone antagonists, and 83% on diuretics. The S-HFR is a valuable tool for improving the management of patients with HF, since it enables participating centres to focus on their own potential for improving diagnoses and medical treatment, through the online reports provided.

    Keyword
    Heart failure; Registry; Diagnostics; Medical treatment
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-52877 (URN)10.1093/eurjhf/hfp175 (DOI)
    Available from: 2010-01-13 Created: 2010-01-12 Last updated: 2017-05-15
    2. A comprehensive assessment of the association between anemia, clinical covariates and outcomes in a population-wide heart failure registry
    Open this publication in new window or tab >>A comprehensive assessment of the association between anemia, clinical covariates and outcomes in a population-wide heart failure registry
    Show others...
    2016 (English)In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 211, 124-131 p.Article in journal (Refereed) Published
    Abstract [en]

    Background: The aim was to investigate the prevalence of, predictors of, and association with mortality and morbidity of anemia in a large unselected cohort of patients with heart failure (HF) and reduced ejection fraction (HFrEF) and to explore if there were specific subgroups of high risk. Methods: In patients with HFrEF in the Swedish Heart Failure Registry, we assessed hemoglobin levels and associations between baseline characteristics and anemia with logistic regression. Using propensity scores for anemia, we assessed the association between anemia and outcomes with Cox regression, and performed interaction and sub-group analyses. Results: There were 24 511 patients with HFrEF (8303 with anemia). Most important independent predictors of anemia were higher age, male gender and renal dysfunction. One-year survival was 75% with anemia vs. 81% without (p &lt; 0.001). In the matched cohort after propensity score the hazard ratio associated with anemia was for all-cause death 1.34 (1.28-1.40; p &lt; 0.0001), CV mortality 1.28 (1.20-1.36; p &lt; 0.0001), and combined CV mortality or HF hospitalization 1.24 (1.18-1.30; p &lt; 0.0001). In interaction analyses, anemia was associated with greater risk with lower age, male gender, EF 30-39%, and NYHA-class I-II. Conclusion: In HFrEF, anemia is associated with higher age, male gender and renal dysfunction and increased risk of mortality and morbidity. The influence of anemia on mortality was significantly greater in younger patients, in men, and in those with more stable HF. The clinical implication of these findings might be in the future to perform targeted treatment studies. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER IRELAND LTD, 2016
    Keyword
    Heart failure; Reduced ejection fraction; Anemia; Outcomes; Observational study
    National Category
    Mathematics Clinical Medicine
    Identifiers
    urn:nbn:se:liu:diva-127741 (URN)10.1016/j.ijcard.2016.02.144 (DOI)000373918100029 ()26999301 (PubMedID)
    Note

    Funding Agencies|Swedish National Board of Health and Welfare; Swedish Association of Local Authorities and Regions; Swedish Society of Cardiology; Linkoping University; Swedish HF Registry foundation

    Available from: 2016-05-12 Created: 2016-05-12 Last updated: 2017-05-15
  • Public defence: 2017-06-02 09:00 Berzeliussalen, Linköping
    Karlsson, Linn
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Chronic Pain and Exercise: Studies on pain intensity, biochemistry, adherence and attitudes2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Chronic pain is common in western countries and entails considerable consequences for the afflicted individuals as well as for the society. Furthermore, chronic pain is complex including an advanced interplay between biological-, psychological- and social aspects. Treatment of chronic pain attempts to decrease pain intensity and increase physical-, psychological- and social functioning. However, the treatment of chronic pain is still not optimized. Different types of physical activity and exercise (PA&E) are commonly applied as non-pharmacological treatment strategies for chronic pain, but the most efficient type and dose of PA&E are unclear. In addition, adherence to prescribed PA&E is often troublesome, which further complicates the application of PA&E as treatment for chronic pain.

    The aim of this thesis is to increase the knowledge about PA&E as treatment for chronic pain regarding pain intensity, biochemical substances, adherence and attitudes.

    The findings of this thesis were that a long-term, home-based PA&E intervention comprising strength exercises as well as stretch exercises decreased pain intensity and increased function in women with chronic neck- and shoulder pain. Using microdialysis technique, differences in pain modulatory biochemical substances were found, before the intervention, in painful trapezius muscle compared to pain-free trapezius muscle. In addition, alterations in pain modulatory substances in painful trapezius muscle after the intervention were found, which possibly could imply peripheral physiological effects of PA&E. Furthermore, psychological factors could be associated to the effects of and adherence to the PA&E intervention. An intention to be physically active were expressed by patients with chronic pain, but a discordance between the intention and PA&E-behaviour were evident, even though the PA&E were experienced as valuable.

    In conclusion, this thesis strengthens the importance of PA&E as treatment for chronic pain. Especially, this thesis increases the knowledge about; possible peripheral pain inhibitory effects after long-term exercise; how psychological factors might affect the results of PA&E; and also about important behavioural aspects that might affect adherence to prescribed PA&E. This thesis highlights the need of more research on physiological pain inhibitory effects of long-term PA&E in chronic pain. Furthermore, improved methods for ensured adherence to prescribed PA&E are necessary in order to optimize the effect of PA&E as treatment for chronic pain.

    List of papers
    1. Evaluation of pain and function after two home exercise programs in a clinical trial on women with chronic neck pain - with special emphasises on completers and responders
    Open this publication in new window or tab >>Evaluation of pain and function after two home exercise programs in a clinical trial on women with chronic neck pain - with special emphasises on completers and responders
    2014 (English)In: BMC Musculoskeletal Disorders, ISSN 1471-2474, Vol. 15, no 6Article in journal (Refereed) Published
    Abstract [en]

    Background: Different types of exercises can help manage chronic neck pain. Supervised exercise interventions are widely used, but these protocols require substantial resources. The aim of this trial, which focused on adherence, was to evaluate two home exercise interventions. Methods: This parallel group randomized controlled trial included 57 women randomly allocated into two groups - a strength training group (STRENGTH, 34 subjects) and a stretching group (STRETCH, 23 subjects). The interventions focused on the neck and shoulder muscles and lasted for 12 months. The STRENGTH group performed weight training and ended each session with stretching exercises. These stretching exercises constituted the entirety of the STRETCH groups training session. Both groups were instructed to exercise three times per week. All the participants kept an exercise diary. In addition, all participants were offered support via phone and e-mail. The primary outcomes were pain intensity and function. The trial included a four-to six-month and a twelve-month follow-up. A completer in this study exercised at least 1,5 times per week during eight unbroken weeks. A responder in this study reported clinically significant improvements on pain and function. The statistical analyses used the Mann Whitney U-test, Wilcoxon signed-rank test, and X-2 test. Results: At four-to six-months, the numbers of completers were 19 in the STRENGTH group and 17 in the STRETCH group. At twelve months, the corresponding numbers were 11 (STRENGTH) and 10 (STRETCH). At four-to six-months, the proportions of subjects reporting clinically important changes (STRENGTH and STRETCH) were for neck pain: 47% and 41%, shoulder pain: 47% and 47%, function: 37% and 29%. At twelve months, the corresponding numbers were for neck pain: 45% and 40%, shoulder pain: 55% and 50%, function: 55% and 20%. Conclusions: No differences in the two primary outcomes between the two interventions were found, a finding that may be due to the insufficient statistical power of the study. Both interventions based on home exercises improved the two primary outcomes, but the adherences were relatively low. Future studies should investigate ways to improve adherence to home exercise treatments.

    Place, publisher, year, edition, pages
    BioMed Central, 2014
    Keyword
    Neck pain; Shoulder pain; Home exercise; Strength training; Stretching; Function
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-104117 (URN)10.1186/1471-2474-15-6 (DOI)000329854700003 ()
    Available from: 2014-02-07 Created: 2014-02-07 Last updated: 2017-05-04
    2. Intramuscular pain modulatory substances before and after exercise in women with chronic neck pain
    Open this publication in new window or tab >>Intramuscular pain modulatory substances before and after exercise in women with chronic neck pain
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    2015 (English)In: European Journal of Pain, ISSN 1090-3801, E-ISSN 1532-2149, Vol. 19, no 8, 1075-1085 p.Article in journal (Refereed) Published
    Abstract [en]

    BackgroundIn peripheral tissue, several substances influence pain and pain modulation. Exercise has been found to decrease pain and improve function for chronic pain conditions, but how and why exercise produces beneficial effects remains unclear. This study investigates whether aspects of pain and concentrations of substances with algesic, analgesic and metabolic functions differ between women with chronic neck shoulder pain (CNSP) and healthy women (CON) and whether changes are found after an exercise intervention for CNSP. MethodsForty-one women with CNSP and 24 CON subjects were included. The participants attended two microdialysis sessions with 4-6 months between the experiments. During this period, the CNSP subjects underwent an exercise intervention. Expression levels of substance P, beta-endorphin, cortisol, glutamate, lactate and pyruvate as well as pain intensity and pressure pain thresholds were analysed. ResultsAt baseline, higher concentrations of glutamate and beta-endorphin and lower concentrations of cortisol in CNSP than CON were found. After exercise, decreased levels of substance P and possibly of glutamate, increased levels of beta-endorphin and cortisol as well as decreased pain intensity and increased pain pressure thresholds were found for CNSP. ConclusionsThe findings at baseline indicated algesic and analgesic alterations in the painful trapezius muscles. The findings for CNSP after the exercise intervention, with changes in peripheral substances and decreased pain intensity and sensitivity, could reflect a long-term physiological effect of the exercise.

    Place, publisher, year, edition, pages
    WILEY-BLACKWELL, 2015
    National Category
    Physiotherapy Physiology
    Identifiers
    urn:nbn:se:liu:diva-121426 (URN)10.1002/ejp.630 (DOI)000360180300005 ()25430591 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [K2011-69X-21874-01-6]; Swedish Council for Working Life and Social Research [2010-0913]

    Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2017-05-04
    3. Associations between psychological factors and the effect of home-based physical exercise in women with chronic neck and shoulder pain.
    Open this publication in new window or tab >>Associations between psychological factors and the effect of home-based physical exercise in women with chronic neck and shoulder pain.
    Show others...
    2016 (English)In: SAGE open medicine, E-ISSN 2050-3121, Vol. 4, 2050312116668933Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: Exercise is often used in the treatment of chronic neck and shoulder muscle pain. It is likely that psychological aspects have an impact on the results of exercise-based treatments.

    OBJECTIVES: (1) To examine the associations between psychological factors and the effect of a home-based physical exercise intervention. (2) To examine differences in psychological factors at baseline between (a) subjects who continued in the trial and those who did not and (b) subjects who completed the intervention and those who did not.

    METHOD: A total of 57 women with chronic neck and shoulder pain were included in a home-based exercise intervention trial. Pain intensity, disability, and psychological factors (anxiety and depression symptoms, catastrophizing, fear-avoidance beliefs, self-efficacy, and pain acceptance) were measured at baseline, after 4-6 months, and after 1 year of exercise. Associations between the psychological factors and changes in pain intensity and disability were analysed, as well as differences in psychological factors at baseline between subjects who continued in and completed the intervention, and those who did not.

    RESULTS: Associations between positive changes in pain intensity and disability were found for low fear-avoidance beliefs and low-pain self-efficacy at baseline. In addition, fear-avoidance beliefs at baseline were higher in the subjects who dropped out of the intervention than in those who continued. Pain acceptance at baseline was higher in the subjects who completed the intervention at the end of the trial.

    CONCLUSION: Particularly, fear-avoidance beliefs and pain self-efficacy should be taken into consideration when implementing home-based physical exercise as treatment for chronic neck pain. In addition, high pain acceptance might improve the adherence to prescribed exercise.

    Keyword
    Exercise, neck pain, psychological factors
    National Category
    Public Health, Global Health, Social Medicine and Epidemiology Psychiatry Family Medicine
    Identifiers
    urn:nbn:se:liu:diva-135743 (URN)10.1177/2050312116668933 (DOI)27688880 (PubMedID)
    Available from: 2017-03-20 Created: 2017-03-20 Last updated: 2017-05-04
  • Public defence: 2017-06-02 13:15 TEMCAS, TEMA-huset, Linköping
    Holm, Marie-Louise
    Linköping University, Department of Thematic Studies, The Department of Gender Studies. Linköping University, Faculty of Arts and Sciences.
    Fleshing out the self: Reimagining intersexed and trans embodied lives through (auto)biographical accounts of the past2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis explores how current ways of imagining possibilities for intersexed and trans embodied lives within medical contexts might be informed by and reimagined through the historical lived experiences of intersexed and trans individuals as they have been articulated in autobiographical accounts.

    Postmodern, queer, intersex, and trans researchers and activists have criticised existing standards of intersex and trans healthcare for limiting the possibilities for diverse embodied lives by articulating certain forms of embodiment and selfhood as more likely to enable a liveable life than others. This has often been done in a medico-legal context by referring to experiences in the past of the unliveability of corporealities and gendersexed situations that differ from privileged positions. With a point of departure in these critiques, this thesis reopens questions about how intersexed and trans people may be embodied and have relations with others by reflecting upon the period of the first three-quarters of the 20th century, when the present standards of care and diagnostic categories were emerging, but had not yet become established.

    Drawing upon a unique set of historical source material from the archives of the Danish Ministry of Justice and the Medico-Legal Council, intersexed and trans persons’ life stories are rearticulated from their own and medico-legal experts’ accounts written in relation to applications for change of legal gendersex status and medical transition. In this way, the process is traced through which these life stories have been repeatedly rearticulated in order to become a usable basis for diagnosis and decision-making. At the same time, the stories are unfolded once more in a rearticulation focusing on their complexity and diversity.

  • Public defence: 2017-06-05 09:00 Originalet, Qulturum, Jönköping
    Slind Olsen, Renate
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Circulating and genetic factors in colorectal cancer: Potential factors for establishing prognosis?2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Colorectal cancer (CRC) is defined as a cancer appearing in the colon or in the rectum. In Sweden, ~ 6300 individuals were diagnosed with the disease in 2014 and ~ 2550 individuals diagnosed with CRC die each year due to their cancer. Surgery is the main treatment option of CRC and a survival rate of ~ 10 % is estimated if distant metastases have developed. It is therefore of importance to find factors that may be useful together with tumour, node, metastasis (TNM) stage to establish early CRC diagnosis, prognosis and follow-up of CRC patients. The aim of this thesis was to study the possible association of CD93, PLA2G4C, PDGF-D and inflammatory cytokines with CRC disease progression.

    In a prospective study approach CD93 and PLA2G4C single nucleotide polymorphisms (SNPs) were of potential importance in CRC prognosis.

    The T/T genotype of CD93 was associated with an increased CD93 expression in CRC tissue. Further, CRC patients carrying this genotype were associated with disseminated CRC at diagnosis and a lower recurrence-free survival after surgery. The A allele of a SNP of PLA2G4C was a stronger predictor for CRC-specific mortality than the conventional risk factors used in the clinic for selection of TNM stage II patients for adjuvant treatment. This indicates that the T/T genotype of CD93 and the A allele of PLA2G4C may be potential genetic factors related to disease severity and spread. Furthermore, they distinguish CRC patients that may benefit from a more comprehensive follow-up and adjuvant treatment.

    To study the putative involvement of PDGF-D in CRC the effects of PDGF-D signalling was studied in vitro. PDGF-D signalling altered the expression of genes of importance in CRC carcinogenesis and proliferation which was blocked by imatinib, a tyrosine kinase inhibitor. This indicates that PDGF-D signalling may be an important pathway in CRC progression and a potential target in CRC treatment.

    The analysis of various inflammatory cytokines in plasma at diagnosis showed an association between high levels and increased total- or CRC-specific mortality two years after surgery. High levels of CCL1 and CCL24 was the only cytokines strongly correlated with a worse CRC prognosis after statistical adjustments and may be of interest for further evaluation.

    In conclusion, this thesis presents circulating and genetic factors such as CD93, PLA2G4C, PDGF-D, CCL1 and CCL24 that may be of importance in CRC progression and may be of clinical value together with TNM stage in establishing prognosis.

    List of papers
    1. CD93 gene polymorphism is associated with disseminated colorectal cancer
    Open this publication in new window or tab >>CD93 gene polymorphism is associated with disseminated colorectal cancer
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    2015 (English)In: International Journal of Colorectal Disease, ISSN 0179-1958, E-ISSN 1432-1262, Vol. 30, no 7, 883-890 p.Article in journal (Refereed) Published
    Abstract [en]

    Cluster of differentiation 93 (CD93) is involved in apoptosis and inflammation and has a suggested role in angiogenesis, and all of which are involved in the development and dissemination of cancer. We evaluated the expression of CD93 and the association with two single nucleotide polymorphisms (SNPs), rs2749812 and rs2749817, as possible biomarkers in colorectal cancer (CRC). Tissue levels and plasma levels of CD93 were measured using an enzyme-linked immunosorbent assay (ELISA). Expression of CD93 was determined by immunohistochemistry, western blot and gene expression analysis. Genotype frequencies were established for the SNPs by real-time polymerase chain reaction (PCR), and the association with tumour stage and survival was analysed. Total CD93 levels were 82 % higher (P less than 0.001) in tumours compared to matched normal tissues. Mean levels of soluble CD93 in plasma were 30 % lower (P less than 0.001) in the patients compared to the controls. The T/T genotype of SNP rs2749817 was more common in stage IV patients, with consequently higher risk of CRC death (T/T vs. C/C and C/T; hazard ratio (HR) = 1.73, 95 % confidence interval (CI) = 1.11-2.67, P = 0.014), and was associated with a higher risk of CRC recurrence after radical operation (T/T vs. C/C and C/T; HR = 2.07, CI = 1.22-3.51, P = 0.007). We showed that the T/T genotype of SNP rs2749817 is associated with disseminated cancer at diagnosis and an increased recurrence rate after radical operation. Patients with this genotype may benefit from early identification.

    Place, publisher, year, edition, pages
    Springer Verlag (Germany), 2015
    Keyword
    Biomarker; Colorectal cancer; Genotype; Prognosis; Single nucleotide polymorphism; Survival
    National Category
    Cancer and Oncology
    Identifiers
    urn:nbn:se:liu:diva-120141 (URN)10.1007/s00384-015-2247-1 (DOI)000356350900003 ()26008729 (PubMedID)
    Note

    Funding Agencies|Foundation of Clinical Cancer Research, Jonkoping [110426-1]; Futurum; Academy of Healthcare; County Council of Jonkoping [FUTURUM-105891]; FORSS, the Research Council of Southeastern Sweden [FORSS-373251]

    Available from: 2015-07-14 Created: 2015-07-13 Last updated: 2017-05-11
    2. Prognostic significance of PLA2G4C gene polymorphism in patients with stage II colorectal cancer.
    Open this publication in new window or tab >>Prognostic significance of PLA2G4C gene polymorphism in patients with stage II colorectal cancer.
    Show others...
    2016 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 55, no 4, 474-479 p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: Phospholipase A2 Group IV C (PLA2G4C) catalyzes the release of certain fatty acids from phospholipids and plays a role in a range of physiological functions, such as remodeling of cell membranes and the production of prostaglandins. Furthermore, it has been proposed that PLA2G4C plays an important role in breast cancer cell chemotaxis. This study aimed to investigate the effect of a single nucleotide polymorphism (SNP) rs1549637 (T>A) of the PLA2G4C gene on the prognosis of colorectal cancer (CRC).

    MATERIAL AND METHODS: Whole blood DNA was extracted from 381 patients with CRC and 618 controls, and a TaqMan SNP genotyping assay was used to determine the distribution of the genotypes. Cancer-specific and disease-free survival was analyzed by Kaplan-Meier graphs and by uni- and multivariable Cox regression.

    RESULTS: The cancer-specific survival differed between the genotypes (p = 0.019) and the carriers of the A allele were associated with the highest risk of CRC death, with a hazard ratio (HR) of 1.72 [95% confidence interval (CI) 1.17-2.53, p = 0.006] compared with homozygous carriers of the T allele. This increased mortality in the carriers with the allele A was especially marked in stage II with an HR of 3.84 (95% CI 1.51-9.78, p = 0.005).

    CONCLUSION: The A allele in PLA2G4C SNP (rs1549637) is associated with a worse prognosis in patients with CRC, especially in stage II disease, and it could be a potential prognostic biomarker in the planning of individual adjuvant therapy in stage II patients.

    Place, publisher, year, edition, pages
    Taylor & Francis Group, 2016
    National Category
    Cancer and Oncology Cell and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-125986 (URN)10.3109/0284186X.2015.1073350 (DOI)000372125400012 ()26364726 (PubMedID)
    Note

    Funding agencies: Futurum; Academy of Healthcare; Region Jonkoping County, Sweden; Foundation of Clinical Cancer Research, Jonkoping Sweden; University College of Health Sciences, Jonkoping, Sweden

    Available from: 2016-03-10 Created: 2016-03-10 Last updated: 2017-05-11
  • Public defence: 2017-06-07 10:15 Planck, Fysikhuset, Linköping
    Lai, Chung-Chuan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase Formation of Nanolaminated Transition Metal Carbide Thin Films2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Research on inherently nanolaminated transition metal carbides is inspired by their unique properties combining metals and ceramics, such as higher damage tolerance, better machinability and lower brittleness compared to the binary counterparts, yet retaining the metallic conductivity. The interesting properties are related to their laminated structure, composed of transition-metalcarbide layers interleaved by non-transition-metal (carbide) layers. These materials in thin-film form are particularly interesting for potential applications such as protective coatings and electrical contacts. The goal of this work is to explore nanolaminated transition metal carbides from the aspects of phase formation and crystal growth during thin-film synthesis. This was realized by studying phases in select material systems synthesized from two major approaches, namely, fromdirect-deposition and post-deposition treatment.

    The first approach was used in studies on the Mo-Ga-C and Zr-Al-C systems. In the former system, intriguing properties have been predicted for the 3D phases and their 2D derivatives (socalled MXenes), while in the latter system, the phases are interesting for nuclear applications. In this work, the discovery of a new Mo-based nanolaminated ternary carbide, Mo2Ga2C, is evidenced from thin-film and bulk processes. Its structure was determined using theoretical and experimental techniques, showing that Mo2Ga2C has Ga double-layers in simple hexagonal stacking between adjacent Mo2C layers, and therefore is structurally very similar to Mo2GaC, except for the additional Ga layers. For the Zr-Al-C system, the optimization of phase composition and structure of Zr2Al3C4 in a thin-film deposition process was studied by evaluating the effect of deposition parameters. I concluded that the formation of Zr2Al3C4 is favored with a plasma flux overstoichiometric in Al, and with a minimum lattice-mismatch to the substrates. Consequently, epitaxial Zr2Al3C4 thin film of high quality were deposited on 4H-SiC(001) substrates at 800 °C.

    With the approach of post-deposition treatment, the studies were focused on a new method of thermally-induced selective substitution reaction of Au for the non-transition-metal layers in nanolaminated carbides. Here, the reaction mechanism has been explored in Al-containing (Ti2AlC

    and Ti3AlC2) and Ga-containing (Mo2GaC and Mo2Ga2C) phases. The Al and Ga in these phases were selectively replaced by Au while the carbide layers remained intact, resulting in the formation of new layered phases, Ti2Au2C, Ti3Au2C2, Mo2AuC, and Mo2(Au1-xGax)2C, respectively. The substitution reaction was explained by fast outward diffusion of the Al or Ga being attracted to the surface Au, in combination with back-filling of Au, which is chemically inert to the carbide layers,to the vacancies.

    The substitution reaction was further applied to Ga-containing nanolaminated carbides, (Cr0.5Mn0.5)2GaC and Mo2GaC, motivated by development of novel magnetic nanolaminates. The former experiment resulted in the formation of (Cr0.5Mn0.5)2AuC, where the retained (Cr0.5Mn0.5)2C layers allowed a comparative study on the magnetic properties under the exchange of Ga for Au. After Au substitution, reduction in the Curie temperature and the saturation magnetization were observed, showing a weakened magnetic exchange interaction of the magnetic (Cr0.5Mn0.5)Clayers across the Au. In the Mo2GaC case, an Fe-containing MAX phase, Mo2AC with 50 at.% of Fe on the A site, was synthesized through selective substitution of Au-Fe alloy for the Ga layers, showing the first direct evidence for Fe in the MAX-phase structure. The substitution of Fe did not take place on another Mo2GaC sample tested for Fe exchange only, indicating the essential role of Au in catalyzing the Fe-substitution reaction.

    The knowledge gained from this thesis work contributes to improved approaches for attaining thin films of nanolaminated transition metal carbides with desired phase composition and crystal quality. The reports on the new nanolaminated phases through exchange interactions are likely to expand the family of nanolaminated carbides and advance their properties, and trigger more studies on related (quasi-) 2D materials.

    List of papers
    1. Mo2Ga2C: a new ternary nanolaminated carbide
    Open this publication in new window or tab >>Mo2Ga2C: a new ternary nanolaminated carbide
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    2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 30, 6560-6563 p.Article in journal (Refereed) Published
    Abstract [en]

    We report the discovery of a new hexagonal Mo2Ga2C phase, wherein two Ga layers - instead of one - are stacked in a simple hexagonal arrangement in between Mo2C layers. It is reasonable to assume this compound is the first of a larger family.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2015
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-117813 (URN)10.1039/c5cc00980d (DOI)000352269000022 ()25768789 (PubMedID)
    Note

    Funding Agencies|Swedish Research Council [621-2011-4420, 642-2013-8020, 621-2014-4890]; Swedish Foundation for Strategic Research through the Synergy Grant FUNCASE Functional Carbides for Advanced Surface Engineering; Future Research Leaders 5 Program; ERC [258509]; Ningbo Natural Science Foundation [2013A610128]; National Natural Science Foundation of China [U1232136]; Knut and Alice Wallenberg Foundation

    Available from: 2015-05-11 Created: 2015-05-08 Last updated: 2017-05-15
    2. Structural and chemical determination of the new nanolaminated carbide Mo2Ga2C from first principles and materials analysis
    Open this publication in new window or tab >>Structural and chemical determination of the new nanolaminated carbide Mo2Ga2C from first principles and materials analysis
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    2015 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 99, 157-164 p.Article in journal (Refereed) Published
    Abstract [en]

    Following our recent discovery of a new nanolaminated carbide, Mo2Ga2C, we herein present a detailed structural and chemical analysis of this phase based on ab initio calculations, X-ray photoelectron spectroscopy, high resolution scanning transmission electron microscopy, and neutron powder diffraction. Calculations suggest an energetically and dynamically stable structure for C in the octahedral sites between the Mo layers, with Ga bilayers - stacked in a simple hexagonal arrangement - between the Mo2C layers. The predicted elastic properties are below those of the related nanolaminate Mo2GaC. The predicted structure, including lattice parameters and atomic positions, is experimentally confirmed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    Place, publisher, year, edition, pages
    PERGAMON-ELSEVIER SCIENCE LTD, 2015
    Keyword
    First principles; Phase stability; Nanolaminated material; Crystal structure; Mo2Ga2C
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-122193 (URN)10.1016/j.actamat.2015.07.063 (DOI)000362145400017 ()
    Note

    Funding Agencies|Swedish Research Council [621-2011-4420, 642-2013-8020, 621-2014-4890]; Swedish Foundation for Strategic Research through the Synergy Grant FUNCASE Functional Carbides for Advanced Surface Engineering; Future Research Leaders 5 Program; ERC [258509]; Knut and Alice Wallenberg Foundation

    Available from: 2015-10-26 Created: 2015-10-23 Last updated: 2017-05-15
  • Public defence: 2017-06-07 13:00 Granitsalen, Linköping
    Lundin, Anna-Carin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Surgery, Orthopedics and Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    Tendinosis in Trigger Finger2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Trigger finger is one of the most common hand conditions, with a prevalence of almost 3%. The aetiology remains unclear even though many causes have been suggested. The prevailing paradigm is that the pathogenesis of trigger finger is ascribed to primary changes in the first fibrous condensation of the tendon sheath (A1-pulley). Several studies have investigated pathology in the pulley, but few have investigated the tendon. The general aim of this thesis was to find out if there is pathology in the trigger finger tendon and to define it.

    We first looked at trigger finger tendon biopsies in a light microscope, and found that they were histologically different from healthy tendons. They showed signs of micro-ruptures, collagen degradation, increased amounts of ground substance, both hyper- and hypo-cellular areas, round active cell nuclei and absence of inflammatory cells, all similar to tendinosis. The histological picture was further assessed by using a scoring system for Achilles tendinosis. The trigger finger tendons scored high, suggesting a similar histopathology.

    Next, we performed a quantitative real-time polymerase chain reaction (qPCR) on trigger finger tendons. We assessed the mRNA expression of 10 genes, which have been described to be differently expressed in Achilles tendinosis (collagen 1 and 3, versican, decorin, biglycan, aggrecan, MMP-2, MMP-3, ADAMTS-5, and TIMP-3). The overall expression pattern agreed with previous studies on Achilles tendinosis, suggesting that the cellular function in trigger finger tendons is disturbed in a similar way as in Achilles tendinosis.

    Recent experimental and observational research has suggested potential side effects of statin treatment on tendons, but firm evidence was lacking. We performed an epidemiological study on two large population-based cohorts. Statin use was found to increase the risk of both trigger finger and tendinosis in the shoulder and Achilles tendons, especially among men. This suggests a similar pathology in trigger finger and tendinosis.

    We have also studied the time to treatment effect after a single injection of glucocorticoid in trigger finger. Our results suggest that 60-80% of patients can expect resolution of the triggering within 14 days, and half of them within seven days. This result allows correct information to be given to the patient and proper planning of follow-ups.

    In conclusion, the pathology in trigger finger tendons is similar to tendinosis in other tendons.

    List of papers
    1. Trigger finger and tendinosis
    Open this publication in new window or tab >>Trigger finger and tendinosis
    2012 (English)In: Journal of Hand Surgery, European Volume, ISSN 1753-1934, E-ISSN 2043-6289, Vol. 37, no 3, 233-236 p.Article in journal (Refereed) Published
    Abstract [en]

    The pathogenesis of trigger finger has generally been ascribed to primary changes in the pulley. Histological examination of the affected tendons has rarely been done. We studied biopsies from tendons of trigger fingers from 29 patients and compared these to biopsies from six intact tendons. We used a modified Movin score, which describes the tendinosis of the Achilles tendon. Trigger finger tendons had a high score (14.2; SD, 2.2) consistent with tendinosis, while the controls were almost normal (2.5; SD, 1.9). This suggests that the tendon is also affected, and that trigger finger is a form of tendinosis.

    Place, publisher, year, edition, pages
    Sage Publications, 2012
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-76086 (URN)10.1177/1753193411421853 (DOI)000300994100007 ()21987275 (PubMedID)
    Available from: 2012-03-26 Created: 2012-03-26 Last updated: 2017-04-25Bibliographically approved
    2. Trigger finger, tendinosis, and intratendinous gene expression
    Open this publication in new window or tab >>Trigger finger, tendinosis, and intratendinous gene expression
    2014 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, 363-368 p.Article in journal (Refereed) Published
    Abstract [en]

    The pathogenesis of trigger finger has generally been ascribed to primary changes in the first annular ligament. In contrast, we recently found histological changes in the tendons, similar to the findings in Achilles tendinosis or tendinopathy. We therefore hypothesized that trigger finger tendons would show differences in gene expression in comparison to normal tendons in a pattern similar to what is published for Achilles tendinosis. We performed quantitative real-time polymerase chain reaction on biopsies from finger flexor tendons, 13 trigger fingers and 13 apparently healthy control tendons, to assess the expression of 10 genes which have been described to be differently expressed in tendinosis (collagen type 1a1, collagen 3a1, MMP-2, MMP-3, ADAMTS-5, TIMP-3, aggrecan, biglycan, decorin, and versican). In trigger finger tendons, collagen types 1a1 and 3a1, aggrecan and biglycan were all up-regulated, and MMP-3and TIMP-3 were down-regulated. These changes were statistically significant and have been previously described for Achilles tendinosis. The remaining four genes were not significantly altered. The changes in gene expression support the hypothesis that trigger finger is a form of tendinosis. Because trigger finger is a common condition, often treated surgically, it could provide opportunities for clinical research on tendinosis.

    Place, publisher, year, edition, pages
    Wiley, 2014
    Keyword
    tendinopathy; tendinosis; stenosing tendovaginitis; tendovaginitis stenosans; quantitative real-time PCR; qPCR
    National Category
    Orthopedics Cell and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-106131 (URN)10.1111/j.1600-0838.2012.01514.x (DOI)000332982700018 ()
    Available from: 2014-04-25 Created: 2014-04-24 Last updated: 2017-04-25
  • Public defence: 2017-06-08 10:15 Ada Lovelace (Visionen), B-huset, ingång 27, Linköping
    Ngaruye, Innocent
    Linköping University, Department of Mathematics, Mathematical Statistics . Linköping University, Faculty of Science & Engineering.
    Contributions to Small Area Estimation: Using Random Effects Growth Curve Model2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation considers Small Area Estimation with a main focus on estimation and prediction for repeated measures data. The demand of small area statistics is for both cross-sectional and repeated measures data. For instance, small area estimates for repeated measures data may be useful for public policy makers for different purposes such as funds allocation, new educational or health programs, etc, where decision makers might be interested in the trend of estimates for a specic characteristic of interest for a given category of the target population as a basis of their planning.

    It has been shown that the multivariate approach for model-based methods in small area estimation may achieve substantial improvement over the usual univariate approach. In this work, we consider repeated surveys taken on the same subjects at different time points. The population from which a sample has been drawn is partitioned into several non-overlapping subpopulations and within all subpopulations there is the same number of group units. The aim is to propose a model that borrows strength across small areas and over time with a particular interest of growth profiles over time. The model accounts for repeated surveys, group individuals and random effects variations.

    Firstly, a multivariate linear model for repeated measures data is formulated under small area estimation settings. The estimation of model parameters is discussed within a likelihood based approach, the prediction of random effects and the prediction of small area means across timepoints, per group units and for all time points are obtained. In particular, as an application of the proposed model, an empirical study is conducted to produce district level estimates of beans in Rwanda during agricultural seasons 2014 which comprise two varieties, bush beans and climbing beans.

    Secondly, the thesis develops the properties of the proposed estimators and discusses the computation of their first and second moments. Through a method based on parametric bootstrap, these moments are used to estimate the mean-squared errors for the predicted small area means. Finally, a particular case of incomplete multivariate repeated measures data that follow a monotonic sample pattern for small area estimation is studied. By using a conditional likelihood based approach, the estimators of model parameters are derived. The prediction of random effects and predicted small area means are also produced.

    List of papers
    1. Small Area Estimation under a Multivariate Linear Model for Repeated measures Data
    Open this publication in new window or tab >>Small Area Estimation under a Multivariate Linear Model for Repeated measures Data
    2016 (English)In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 103, no 2Article in journal (Refereed) Published
    Abstract [en]

    In this article, Small Area Estimation under a Multivariate Linear model for repeated measures data is considered. The proposed model aims to get a model which borrows strength both across small areas and over time. The model accounts for repeated surveys, grouped response units and random effects variations. Estimation of model parameters is discussed within a likelihood based approach. Prediction of random effects, small area means across time points and per group units are derived. A parametric bootstrap method is proposed for estimating the mean squared error of the predicted small area means. Results are supported by a simulation study.

    Place, publisher, year, edition, pages
    New York: Taylor & Francis, 2016
    National Category
    Probability Theory and Statistics Control Engineering Applied Mechanics Geophysics
    Identifiers
    urn:nbn:se:liu:diva-137116 (URN)10.1080/03610926.2016.1248784 (DOI)
    Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2017-05-09Bibliographically approved
    2. Crop yield estimation at district level for agricultural seasons 2014 in Rwanda
    Open this publication in new window or tab >>Crop yield estimation at district level for agricultural seasons 2014 in Rwanda
    2016 (English)In: African Journal of Applied Statistics, ISSN 2316-0861, Vol. 3, no 1, 69-90 p.Article in journal (Refereed) Published
    Abstract [en]

    In this paper, we discuss an application of Small Area Estimation (SAE) tech- niques under a multivariate linear regression model for repeated measures data to produce district level estimates of crop yield for beans which comprise two varieties, bush beans and climbing beans in Rwanda during agricultural seasons 2014. By using the micro data of National Institute of Statistics of Rwanda (NISR) obtained from the Seasonal Agricul- tural Survey (SAS) 2014 we derive efficient estimates which show considerable gain. The considered model and its estimates may be useful for policy-makers or for further analyses. 

    National Category
    Probability Theory and Statistics
    Identifiers
    urn:nbn:se:liu:diva-136721 (URN)10.16929/ajas/2016.69.203 (DOI)
    Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2017-05-09Bibliographically approved
    3. Mean-Squared errors of small area estimators under a multivariate linear model for repeated measures data
    Open this publication in new window or tab >>Mean-Squared errors of small area estimators under a multivariate linear model for repeated measures data
    2017 (English)Report (Other academic)
    Abstract [en]

    In this paper, we discuss the derivation of the first and second moments for the proposed small area estimators under a multivariate linear model for repeated measures data. The aim is to use these moments to estimate the mean-squared errors (MSE) for the predicted small area means as a measure of precision. A two stage estimator of MSE is obtained. At the first stage, we derive the MSE when the covariance matrices are known. To obtain an unbiased estimator of the MSE, at the second stage, a method based on parametric bootstrap is  proposed for bias correction and for prediction error that reects the uncertainty when the unknown covariance is replaced by its suitable estimator.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017. 19 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 2017:05
    Keyword
    Mean-squared errors, Multivariate linear model, Repeated measures data, Small area estamation
    National Category
    Probability Theory and Statistics
    Identifiers
    urn:nbn:se:liu:diva-137113 (URN)LiTH-MAT-R--2017/05--SE (ISRN)
    Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2017-05-10Bibliographically approved
    4. Small area estimation under a multivariate linear model for incomplete repeated measures data
    Open this publication in new window or tab >>Small area estimation under a multivariate linear model for incomplete repeated measures data
    2017 (English)Report (Other academic)
    Abstract [en]

    In this paper, the issue of analysis of multivariate repeated measures data that follow a monotonic sample pattern for small area estimation is addressed. Random effects growth curve models with covariates for both complete and incomplete data are formulated. A conditional likelihood based approach is proposed for estimation of the mean parameters and covariances. Further, the prediction of random effects and predicted small area means are also discussed. The proposed techniques may be useful for small area estimation under longitudinal surveys with grouped response units and drop outs.

    Place, publisher, year, edition, pages
    Linköping: Linköping University Electronic Press, 2017. 12 p.
    Series
    LiTH-MAT-R, ISSN 0348-2960 ; 2017:06
    Keyword
    Conditional likelihood, Multivariate linear model, Monotone sample, Repeated measures data.
    National Category
    Probability Theory and Statistics
    Identifiers
    urn:nbn:se:liu:diva-137118 (URN)LiTH-MAT-R--2017/06--SE (ISRN)
    Available from: 2017-05-05 Created: 2017-05-05 Last updated: 2017-05-09Bibliographically approved
  • Public defence: 2017-06-08 13:00 Hugo Theorell, Llinköping
    Cros, Olivier
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Structural properties of the mastoid using image analysis and visualization2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented in a CT scan. Where the conventional clinical CT scanner lacks level of minute details, micro-CT scanning provides an overwhelming amount of ne details. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this boneawakens the curiosity of the experimenter, especially with the correct visualization settings.

    This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scans. The study compared current results with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange.

    Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative pre-analysis were performed and reported. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis suggest these microchannels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.

    The knowledge gained from analysing the micro-channels as locally providing blood to the mucosa, led to the consideration of how inflammation of the mucosa could impact the pneumatization of the mastoid air cell system. Though very primitive, a 3D shape analysis of the mastoid air cell system was carried out. The mastoid air cell system was first represented in a compact form through a medial axis, from which medial balls could be used. The medial balls, representative of how large the mastoid air cells can be locally, were used in two complementary clustering methods, one based on the size diameter of the medial balls and one based on their location within the mastoid air cell system. From both quantitative and qualitative statistics, it was possible to map the clusters based on pre-defined regions already described in the literature, which opened the door for new hypotheses concerning the effect of mucosal inflammation on the mastoid pneumatization.

    Last but not least, discovery of other structures, previously unreported in the literature, were also visually observed and briefly discussed in this thesis. Further analysis of these unknown structures is needed.

    List of papers
    1. Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Open this publication in new window or tab >>Determination of the mastoid surface area and volume based on micro-CT scanning of human temporal bone: Geometrical parameters dependence on scanning resolutions
    Show others...
    2016 (English)In: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 340, 127-134 p.Article in journal (Other academic) Published
    Abstract [en]

    The mastoid air cell system (MACS) with its large complex of interconnected air cells reflects an enhanced surface area (SA) relative to its volume (V), which may indicate that the MACS is adapted to gas exchange and has a potential role in middle ear pressure regulation. Thus, these geometric parameters of the MACS have been studied by high resolution clinical CT scanning. However, the resolution of these scans is limited to a voxel size of around 0.6 mm in all dimensions, and so, the geometrical parameters are also limited. Small air cells may appear below the resolution and cannot be detected. Such air cells may contribute to a much higher SA than the V, and thus, also the SA/V ratio. More accurate parameters are important for analysis of the function of the MACS including physiological modeling.

    Our aim was to determine the SA, V, and SA/V ratio in MACS in human temporal bones at highest resolution by using micro-CT-scanning. Further, the influence of the resolution on these parameters was investigated by downsampling the data. Eight normally aerated temporal bones were scanned at the highest possible resolution (30-60 μm). The SA was determined using a triangular mesh fitted onto the segmented MACS. The V was determined by summing all the voxels containing air. Downsampling of the original data was applied four times by a factor of 2.

    The mean SA was 194 cm2, the mean V was 9 cm3, and the mean SA/V amounted to 22 cm-1. Decreasing the resolution resulted in a non-linear decrement of SA and SA/V, whereas V was mainly independent of the resolution.

    The current study found significantly higher SA and SA/V compared with previous studies using clinical CT scanning at lower resolutions. These findings indicate a separate role of the MACS compared with the tympanum, and the results are important for a more accurate modeling of the middle ear physiology.

    Keyword
    Mastoid air cells; medical imaging; micro-CT; surface area; volume
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-122176 (URN)10.1016/j.heares.2015.12.005 (DOI)000386417900016 ()
    Available from: 2015-10-23 Created: 2015-10-23 Last updated: 2017-05-10Bibliographically approved
    2. Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning
    Open this publication in new window or tab >>Micro-channels in the mastoid anatomy. Indications of a separate blood supply of the air cell system mucosa by micro-CT scanning
    Show others...
    2013 (English)In: Hearing Research, ISSN 0378-5955, E-ISSN 1878-5891, Vol. 301, 60-65 p.Article in journal (Refereed) Published
    Abstract [en]

    The mastoid air cell system has traditionally been considered to have a passive role in gas exchange and pressure regulation of the middle ear possibly with some acoustic function. However, more evidence has focused on the mucosa of the mastoid, which may play a more active role in regulation of middle ear pressure.

    In this study we have applied micro-CT scanning on a series of three human temporal bones. This approach greatly enhances the resolution (40–60 μm), so that we have discovered anatomical details, which has not been reported earlier. Thus, qualitative analysis using volume rendering has demonstrated notable micro-channels connecting the surface of the compact bone directly to the mastoid air cells as well as forming a network of connections between the air cells. Quantitative analysis on 2D slices was employed to determine the average diameter of these micro-channels (158 μm; range = 40–440 μm) as well as their density at a localized area (average = 75 cm−2; range = 64–97 cm−2).

    These channels are hypothesized to contain a separate vascular supply for the mastoid mucosa. However, future studies of the histological structure of the micro-channels are warranted to confirm the hypothesis. Studies on the mastoid mucosa and its blood supply may improve our knowledge of its physiological properties, which may have important implications for our understanding of the pressure regulation of the middle ear.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keyword
    mastoid, micro CT, middle ear
    National Category
    Otorhinolaryngology Radiology, Nuclear Medicine and Medical Imaging Medical Image Processing
    Identifiers
    urn:nbn:se:liu:diva-92813 (URN)10.1016/j.heares.2013.03.002 (DOI)000320478100009 ()23518400 (PubMedID)
    Available from: 2013-05-22 Created: 2013-05-22 Last updated: 2017-05-10Bibliographically approved
    3. Structural Analysis of Micro-channels in Human Temporal Bone
    Open this publication in new window or tab >>Structural Analysis of Micro-channels in Human Temporal Bone
    2015 (English)In: IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, Institute of Electrical and Electronics Engineers (IEEE), 2015, 9-12 p.Conference paper (Refereed)
    Abstract [en]

    Recently, numerous micro-channels have been discovered in the human temporal bone by micro-CT-scanning. Preliminary structure of these channels has suggested they contain a new separate blood supply for the mucosa of the mastoid air cells, which may have important functional implications. This paper proposes a structural analysis of the microchannels to corroborate this role. A local structure tensor is first estimated. The eigenvalues obtained from the estimated local structure tensor were then used to build probability maps representing planar, tubular, and isotropic tensor types. Each tensor type was assigned a respective RGB color and the full structure tensor was rendered along with the original data. Such structural analysis provides new and relevant information about the micro-channels but also their connections to mastoid air cells. Before carrying a future statistical analysis, a more accurate representation of the micro-channels in terms of local structure tensor analysis using adaptive filtering is needed.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2015
    Series
    IEEE International Symposium on Biomedical Imaging, ISSN 1945-7928
    Keyword
    Human temporal bone, mastoid, microchannels, quadrature filters, structure tensor, visualization
    National Category
    Radiology, Nuclear Medicine and Medical Imaging
    Identifiers
    urn:nbn:se:liu:diva-122177 (URN)10.1109/ISBI.2015.7163804 (DOI)000380546000003 ()978-1-4799-2374-8 (ISBN)
    Conference
    IEEE 12th International Symposium on Biomedical Imaging (ISBI), 2015 IEEE 12th International Symposium on, 16-19 April, New York, USA
    Available from: 2015-10-23 Created: 2015-10-23 Last updated: 2017-05-10Bibliographically approved
    4. Enhancement of micro-channels within the human mastoid bone based on local structure tensor analysis
    Open this publication in new window or tab >>Enhancement of micro-channels within the human mastoid bone based on local structure tensor analysis
    2016 (English)In: Image Proceessing Theory, Tools and Apllications, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    Numerous micro-channels have recently been discovered in the human temporal bone by x-ray micro-CT-scanning. After a preliminary study suggesting that these micro-channels form a separate blood supply for the mucosa of the mastoid air cells, a structural analysis of the micro-channels using a local structure tensor was carried out. Despite the high-resolution of the micro-CT scan, presence of noise within the air cells along with missing information in some micro-channels suggested the need of image enhancement. This paper proposes an adaptive enhancement of the micro-channels based on a local structure analysis while minimizing the impact of noise on the overall data. Comparison with an anisotropic diffusion PDE based scheme was also performed.

    Place, publisher, year, edition, pages
    IEEE, 2016
    Series
    International Conference on Image Processing Theory Tools and Applications (IPTA), E-ISSN 2154-512X
    Keyword
    Micro-channels, Structure tensor analysis, Image enhancement, Adaptive filtering, Human temporal bone, Mastoid bone
    National Category
    Medical Engineering
    Identifiers
    urn:nbn:se:liu:diva-134434 (URN)10.1109/IPTA.2016.7821019 (DOI)000393589800071 ()9781467389105 (ISBN)9781467389112 (ISBN)
    Conference
    6th International Conference on Image Processing Theory Tools and Applications (IPTA), Oulu, Finland, 12-15 December 2016
    Note

    Funding agencies: Obel Family Foundation (Denmark)

    Available from: 2017-02-13 Created: 2017-02-13 Last updated: 2017-05-10
  • Public defence: 2017-06-09 09:00 Plank, Fysikhuset, Linköping
    Fallahshahroudi, Amir
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Domestication Effects on the Stress Response in Chickens: Genetics, Physiology, and Behaviour2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Animal domestication, the process where animals become adapted to living in proximity to humans, is associated with the alteration of multiple traits, including decreased fearfulness and stress response. With an estimated population of 50 billion, the domesticated chicken is the most populous avian species in the world. Hundreds of chicken breeds have been developed for meat and egg production, hobby or research purposes. Multidirectional selection and the relaxation of natural selection in captivity have created immense phenotypic diversity amongst domesticates in a relatively short evolutionary time. The extensive phenotypic diversity, existence of the wild ancestor, and feasibility of intercrossing various breeds makes the chicken a suitable model animal for deciphering genetic determinants of complex traits such as stress response. We used chicken domestication as a model to gain insights about the mechanisms that regulate stress response in an avian species. We studied behavioural and physiological stress response in the ancestral Red Junglefowl and one of its domesticated progenies, White Leghorn. An advanced intercross between the aforementioned breeds was later used to map genetic loci underlying modification of stress response. The general pattern of the stress response in chickens was comparable with that reported in mammals, however we identified distinctive differences in the stress modulatory pathways in chickens. We showed that changes in the expression levels of several stress modulatory genes in the brain, the pituitary and the adrenal glands underlie the observed modified stress response in domesticated chickens. Using quantitative trait loci (QTL) mapping, several QTL underlying stress induced corticosterone, aldosterone and baseline dehydroepiandrosterone (DHEA) levels were detected. As a next step, we combined QTL mapping with gene expression (eQTL) mapping and narrowed two QTL down to the putative causal genes, SERPINA10 and PDE1C. Both of these genes were differentially expressed in the adrenal glands of White Leghorn and the Red Junglefowl, had overlapping eQTL with hormonal QTL, and their expression levels in the adrenal glands were correlated with plasma levels of corticosterone and al-dosterone. These two genes thus serve as strong candidates for further functional investigation concerning modification of the stress response during domestication. This dissertation increase the knowledge about genetics and physiology of the stress response in an avian species and its modification during domestication. Our findings expand the basic knowledge about the stress response in chicken, which can potentially be used to improve welfare through appropriate genetic selection.

    List of papers
    1. Domestication effects on behavioural and hormonal responses to acute stress in chickens
    Open this publication in new window or tab >>Domestication effects on behavioural and hormonal responses to acute stress in chickens
    Show others...
    2014 (English)In: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 133, 161-169 p.Article in journal (Refereed) Published
    Abstract [en]

    Comparative studies have shown that alterations in physiology, morphology and behaviour have arisen due tothe domestication. A driving factor behind many of the changes could be a shift in stress responses,withmodifiedendocrine and behavioural profiles. In the present study we compared two breeds of chicken (Gallus gallus), thedomesticWhite Leghorn (WL) egg laying breed and its ancestor, the Red Junglefowl (RJF). Birds were exposed toan acute stress event, invoked by 3 or 10 min of physical restraint. Theywere then continuouslymonitored for theeffects on a wide range of behaviours during a 60 min recovery phase. Blood samples were collected from thechicken at baseline, and after 10 and 60 min following a similar restraint stress, and the samples wereanalyzed for nine endogenous steroids of the HPA and HPG axes. Concentration of the steroids was determinedusing validated liquid chromatography tandem mass spectrometry methods. In RJF, an immediate behaviouralresponse was observed after release from restraint in several behaviours, with a relatively fast return to baselinewithin 1 h. In WL, somebehaviourswere affected for a longer period of time, and others not at all. Concentrationsof corticosterone increasedmore in RJF, but returned faster to baseline compared toWL. A range of baseline levelsfor HPG-related steroids differed between the breeds, and they were generally more affected by the stress in WLthan in RJF. In conclusion, RJF reacted stronger both behaviourally and physiologically to the restraint stress, butalso recovered faster. This would appear to be adaptive under natural conditions, whereas the stress recovery ofdomesticated birds has been altered by domestication and breeding for increased reproductive output.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keyword
    Corticosterone Recovery Restraint White Leghorn Red Junglefowl
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-107167 (URN)10.1016/j.physbeh.2014.05.024 (DOI)000340315100022 ()
    Note

    Funders: Swedish Research Council (VR) [621-2011-4731]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) [221-2011-1088]; ERC (project Genewell) [322206]; Swedish Centre of Excellence in Animal Welfare; ARUP Institute for Clinical and Experimental Pathology

    Available from: 2014-06-09 Created: 2014-06-09 Last updated: 2017-05-15
    2. Domestication Effects on Stress Induced Steroid Secretion and Adrenal Gene Expression in Chickens
    Open this publication in new window or tab >>Domestication Effects on Stress Induced Steroid Secretion and Adrenal Gene Expression in Chickens
    Show others...
    2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, 1-10 p., 15345Article in journal (Refereed) Published
    Abstract [en]

    Understanding the genetic basis of phenotypic diversity is a challenge in contemporary biology. Domestication provides a model for unravelling aspects of the genetic basis of stress sensitivity. The ancestral Red Junglefowl (RJF) exhibits greater fear-related behaviour and a more pronounced HPA-axis reactivity than its domesticated counterpart, the White Leghorn (WL). By comparing hormones (plasmatic) and adrenal global gene transcription profiles between WL and RJF in response to an acute stress event, we investigated the molecular basis for the altered physiological stress responsiveness in domesticated chickens. Basal levels of pregnenolone and dehydroepiandrosterone as well as corticosterone response were lower in WL. Microarray analysis of gene expression in adrenal glands showed a significant breed effect in a large number of transcripts with over-representation of genes in the channel activity pathway. The expression of the best-known steroidogenesis genes were similar across the breeds used. Transcription levels of acute stress response genes such as StAR, CH25 and POMC were upregulated in response to acute stress. Dampened HPA reactivity in domesticated chickens was associated with changes in the expression of several genes that presents potentially minor regulatory effects rather than by means of change in expression of critical steroidogenic genes in the adrenal.

    Place, publisher, year, edition, pages
    Nature Publishing Group, 2015
    National Category
    Bioinformatics and Systems Biology
    Identifiers
    urn:nbn:se:liu:diva-122305 (URN)10.1038/srep15345 (DOI)000362885300001 ()26471470 (PubMedID)
    Note

    Funding agencies: Swedish Research Council (VR) [621-2011-4731]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) [221-2011-1088]; SRC [621-2011-5523]; ERC [322206]; Swedish Centre of Excellence in Animal Welfare

    Available from: 2015-10-28 Created: 2015-10-28 Last updated: 2017-05-15
    3. Genetic and Targeted eQTL Mapping Reveals Strong Candidate Genes Modulating the Stress Response During Chicken Domestication.
    Open this publication in new window or tab >>Genetic and Targeted eQTL Mapping Reveals Strong Candidate Genes Modulating the Stress Response During Chicken Domestication.
    Show others...
    2017 (English)In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, Vol. 7, no 2Article in journal (Refereed) Published
    Abstract [en]

    The stress response has been largely modified in all domesticated animals, offering a strong tool for genetic mapping. In chickens, ancestral Red Junglefowl react stronger both in terms of physiology and behavior to a brief restraint stress than domesticated White Leghorn, demonstrating modified functions of the hypothalamic-pituitary-adrenal (HPA) axis. We mapped quantitative trait loci (QTL) underlying variations in stress-induced hormone levels using 232 birds from the 12th generation of an advanced intercross between White Leghorn and Red Junglefowl, genotyped for 739 genetic markers. Plasma levels of corticosterone, dehydroepiandrosterone (DHEA), and pregnenolone (PREG) were measured using LC-MS/MS in all genotyped birds. Transcription levels of the candidate genes were measured in the adrenal glands or hypothalamus of 88 out of the 232 birds used for hormone assessment. Genes were targeted for expression analysis when they were located in a hormone QTL region and were differentially expressed in the pure breed birds. One genome-wide significant QTL on chromosome 5 and two suggestive QTL together explained 20% of the variance in corticosterone response. Two significant QTL for aldosterone on chromosome 2 and 5 (explaining 19% of the variance), and one QTL for DHEA on chromosome 4 (explaining 5% of the variance), were detected. Orthologous DNA regions to the significant corticosterone QTL have been previously associated with the physiological stress response in other species but, to our knowledge, the underlying gene(s) have not been identified. SERPINA10 had an expression QTL (eQTL) colocalized with the corticosterone QTL on chromosome 5 and PDE1C had an eQTL colocalized with the aldosterone QTL on chromosome 2. Furthermore, in both cases, the expression levels of the genes were correlated with the plasma levels of the hormones. Hence, both these genes are strong putative candidates for the domestication-induced modifications of the stress response in chickens. Improved understanding of the genes associated with HPA-axis reactivity can provide insights into the pathways and mechanisms causing stress-related pathologies.

    Place, publisher, year, edition, pages
    The Genetics Society, 2017
    Keyword
    animal, domestication, quantitative trait, genes, corticosterone, aldosterone
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-134649 (URN)10.1534/g3.116.037721 (DOI)000394357100015 ()27974436 (PubMedID)
    Note

    Funding agencies: Swedish Research Council (SRC) (Vetenskapsradet) [621-2011-4731]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Forskningsradet for Miljo, Areella Naringar och Samhallsbyggande) [221-2011-1088]; European Research Co

    Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2017-05-15
    4. QTL mapping of stress related gene expression in a cross between domesticated chickens and ancestral red junglefowl.
    Open this publication in new window or tab >>QTL mapping of stress related gene expression in a cross between domesticated chickens and ancestral red junglefowl.
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    2017 (English)In: Molecular and Cellular Endocrinology, ISSN 0303-7207, E-ISSN 1872-8057, Vol. 446, 52-58 p., S0303-7207(17)30090-4Article in journal (Refereed) Published
    Abstract [en]

    Domestication of animals is associated with numerous alterations in physiology, morphology, and behavior. Lower reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and reduced fearfulness is seen in most studied domesticates, including chickens. Previously we have shown that the physiological stress response as well as expression levels of hundreds of genes in the hypothalamus and adrenal glands are different between domesticated White Leghorn and the progenitor of modern chickens, the Red Junglefowl. To map genetic loci associated with the transcription levels of genes involved in the physiological stress response, we conducted an eQTL analysis in the F12 generation of an inter-cross between White Leghorn and Red Junglefowl. We selected genes for further studies based on their known function in the regulation of the HPA axis or sympathoadrenal (SA) system, and measured their expression levels in the hypothalamus and the adrenal glands after a brief stress exposure (physical restraint). The expression values were treated as quantitative traits for the eQTL mapping. The plasma levels of corticosterone were also assessed. We analyzed the correlation between gene expression and corticosterone levels and mapped eQTL and their potential effects on corticosterone levels. The effects on gene transcription of a previously found QTL for corticosterone response were also investigated. The expression levels of the glucocorticoid receptor (GR) in the hypothalamus and several genes in the adrenal glands were correlated with the post-stress levels of corticosterone in plasma. We found several cis- and trans-acting eQTL for stress-related genes in both hypothalamus and adrenal. In the hypothalamus, one eQTL for c-FOS and one QTL for expression of GR were found. In the adrenal tissue, we identified eQTL for the genes NR0B1, RGS4, DBH, MAOA, GRIN1, GABRB2, GABRB3, and HSF1. None of the found eQTL were significant predictors of corticosterone levels. The previously found QTL for corticosterone was associated with GR expression in hypothalamus. Our data suggests that domestication related modification in the stress response is driven by changes in the transcription levels of several modulators of the HPA and SA systems in hypothalamus and adrenal glands and not by changes in the expression of the steroidogenic genes. The presence of eQTL for GR in hypothalamus combined with the negative correlation between GR expression and corticosterone response suggests GR as a candidate for further functional studies regarding modification of stress response during chicken domestication.

    Keyword
    Animal domestication, HPA axis, QTL, Stress response, eQTL
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-136027 (URN)10.1016/j.mce.2017.02.010 (DOI)000399509600006 ()28189567 (PubMedID)
    Note

    Funding agencies: Swedish Research Council (VR) [621-2011-4731]; Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) [221-2011-1088]; ERC [Genewell 322206]; SRC grant [VR 621-2011-4423, 2015-4870]; Swedish Centre of Excellence in A

    Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2017-05-18
  • Public defence: 2017-06-09 10:15 ACAS, hus A, Linköping
    Liu, Linn
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    A systematic approach for major renovation of residential buildings2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Sweden, buildings are responsible for about 40 % of total energy use and about 10 % of total CO2 emissions Today more than 60 % of existing Swedish residential buildings are over 40 years old and are in need of major renovation. In addition, 15 % of all multi-family buildings and 27 % of all single-family houses were built before 1945. The increased energy use and threat from CO2 emissions of the building sector create a need for energy efficiency. The important role that renovation of residential buildings will play in reducing the total energy used by the Swedish building sector as well as in reducing primary energy use and CO2 emissions on both the national and global levels has been the impetus for the studies included in this thesis.

    The aim of the current research is to develop a methodology from a system perspective which can be used to analyze the energy use, optimal life cycle cost (LCC), energy efficiency measure (EEM) package, indoor environment, CO2 emissions, and primary energy use of a building or a community during major renovation. The developed methodology accomplished at three different levels, i.e. building level, cluster level and district level. The methodology considers both energy efficiency and economic viability during building renovation and will also play an important role in overall urban planning. The studied buildings include both non-listed and listed residential buildings and the tools used include building energy simulation (BES), survey, technical measurements, LCC optimization and building categorization.

    The results show that the combination of BES, technical measurements and surveys provides a holistic approach for evaluation of energy use and indoor environment of the studied residential buildings. The results from the current study also show that the 2020 energy target, i.e., reduction of energy use by 20 %, for the building sector can be achieved by all the studied building types and that the total LCC of these buildings are below the cost-optimal point. In comparison, the 2050 energy target, i.e., reduction of energy use by 50 %, for the building sector may be achieved by the non-listed buildings, but when the constraints relevant to listed buildings are added the cost-optimality changes as some EEMs in direct conflict with the building’s heritage value may not be implemented.

    The investigation of primary energy use and CO2 emissions by the residential buildings show that the higher the energy saving, the lower the primary energy use becomes, and vice versa. With the same energy saving, the heating system with higher primary energy factor results in higher primary energy use. From a CO2 emissions point of view, EEM packages proposed to help buildings connected to a CHP based district heating system, to reduce the energy use or LCC are not consistently effective. Since these EEM packages will reduce district heating demand, the electricity produced in the CHP plant will also decrease. When the biomass is considered a limited resource, measures such as investment in a biofuel boiler are not favourable from the CO2 emissions point of view. The current study has also shown that combining building categorization method and LCC optimization method will help the community to reduce its energy use, primary energy use and CO2 emissions in a systematic and strategic way.

    List of papers
    1. Comprehensive investigation on energy retrofits in eleven multi-family buildings in Sweden
    Open this publication in new window or tab >>Comprehensive investigation on energy retrofits in eleven multi-family buildings in Sweden
    2014 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 84, 704-715 p.Article in journal (Refereed) Published
    Abstract [en]

    Rapidly growing energy use in the building sector is considered a serious problem by both the European Union (EU) and Sweden. Reducing energy demand in the building sector is important for Sweden in order to reach national energy goals for reduced energy use and CO2 emissions in the future. This project aims to find energy efficiency potential in multifamily buildings in the Gävleborg region, which is a cold climate region in Sweden. Measurements and simulations have been made on eleven multifamily buildings from the whole region. The results include different energy efficiency measure packages, profitability analysis of individual measures and packages, and primary energy use analysis. The paper also includes CO2 emissions reduction analysis based on different methods. The project shows that the multifamily buildings in the Gävleborg region have good potential to reduce their energy use by more than 50%, which in turn will contribute to 43% primary energy reduction and 48% CO2 emissions reduction.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-111051 (URN)10.1016/j.enbuild.2014.08.044 (DOI)000345182000070 ()
    Available from: 2014-10-06 Created: 2014-10-06 Last updated: 2017-05-16Bibliographically approved
    2. Evaluating indoor environment of a retrofitted multi-family building with improved energy performance in Sweden
    Open this publication in new window or tab >>Evaluating indoor environment of a retrofitted multi-family building with improved energy performance in Sweden
    2015 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 102, 32-44 p.Article in journal (Refereed) Published
    Abstract [en]

    The building sector within both the EU and Sweden accounts for about 40% of total energy use. It is therefore important to introduce energy efficiency measures in this sector in order to meet the national implementation of the Building Performance Directive. Retrofits that result in improved energy performance are important in order to meet national energy targets, but the impact on the indoor environment has to be considered. Properly chosen energy efficiency measures may affect the indoor environment positively. One retrofitted multi-family building, located in the city of Linkoping, Sweden, was chosen as the study object. The building represents a common type of construction in Sweden. This study presents an evaluation of both the indoor environment and energy use of the retrofitted building in comparison with a similar non-retrofitted building from the same area. The results show that the building has potential to reach a 39% reduction of space heating demand. The indoor environment has been improved compared to the non-retrofitted building. Adding external blinds from 15 May to 15 September between 10am-12pm on the east side and 12pm-3pm on the west side seems to be the best option for improving the indoor climate during summer. (c) 2015 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Multi-family building; Retrofit; Building energy simulation; Energy use; Indoor environment
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-120720 (URN)10.1016/j.enbuild.2015.05.021 (DOI)000358458100003 ()
    Note

    Funding Agencies|Swedish Energy Agency

    Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2017-05-16
    3. A Method to Assess the Potential for and Consequences of Energy Retrofits in Swedish Historic Buildings
    Open this publication in new window or tab >>A Method to Assess the Potential for and Consequences of Energy Retrofits in Swedish Historic Buildings
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    2014 (English)In: The Historic Environment: Policy & Practice, ISSN 1756-7505, E-ISSN 1756-7513, Vol. 5, no 2, 150-166 p.Article in journal (Refereed) Published
    Abstract [en]

    The Swedish research project Potential and Policies for Energy Efficiency in Swedish Historic Buildings aims to investigate the interdependency between political energy targets and effects on the built heritage. The first part of this paper presents an iterative and interactive method to assess the potential for and consequences of improving the energy performance in a stock of historic buildings. Key elements in the method are: categorisation of the building stock, identifying targets, assessment of measures, and life-cycle cost optimisation. In the second part of the paper, the method is applied to a typical Swedish building. The selected case study shows how the method allows for an interaction between the quantitative assessment of the techno-economic optimisation and the qualitative assessment of vulnerability and other risks. Through a multidisciplinary dialogue and iteration it is possible to arrive at a solution that best balances energy conservation and building conservation in a given decision context.

    Place, publisher, year, edition, pages
    Maney Publishing, 2014
    Keyword
    cultural significance; energy efficiency; heritage values; historic buildings; life-cycle cost
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-109231 (URN)10.1179/1756750514Z.00000000055 (DOI)000338773000006 ()
    Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-05-16Bibliographically approved
    4. LCC assessments and environmental impacts on the energy renovation of a multi-family building from the 1890s
    Open this publication in new window or tab >>LCC assessments and environmental impacts on the energy renovation of a multi-family building from the 1890s
    2016 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 133, 823-833 p.Article in journal (Refereed) Published
    Abstract [en]

    The 2020 and 2050 energy targets increase requirements on energy performance in the building stock, thus affecting both listed and non-listed buildings. It is important to select appropriate and cost-optimal energy efficiency measures, using e.g. Life Cycle Cost (LCC) optimization. The aim of this paper is to find cost-optimal packages of energy efficiency measures (EEMs) as well as to explore the effects of specific predesigned energy target values for a listed Swedish multi-family building from the 1890s. The purpose is also to show the effects on energy use, LCC, primary energy use and CO2 emissions of different energy targets, discount rates, electricity prices and geographic locations. The results show that separate energy targets could be an effective way to simplify the implementation for listed buildings. Furthermore, a cost-optimal package of EEMs is more sensitive to changes in discount rate than in electricity price. The energy renovation has impact on the primary energy use and CO2 emissions. The lower the discount rate is, the more EEMs will be implemented and the easier the national energy targets may be achieved. A higher electricity price also leads to more EEMs being implemented but at the same time higher running costs. (C) 2016 Elsevier B.V. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER SCIENCE SA, 2016
    Keyword
    LCC assessments; Environmental impacts; Energy efficiency measures package; Listed/non-listed building; Renovation; Energy targets
    National Category
    Energy Systems
    Identifiers
    urn:nbn:se:liu:diva-133507 (URN)10.1016/j.enbuild.2016.10.040 (DOI)000389087300072 ()
    Note

    Funding Agencies|Swedish Energy Agency

    Available from: 2016-12-30 Created: 2016-12-29 Last updated: 2017-05-16
  • Public defence: 2017-06-09 10:15 TEMCAS, hus T, Linköping
    Genero, Magalí Martí
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Microbial Communities in Boreal Peatlands: Responses to Climate Change and Atmospheric Nitrogen and Sulfur Depositions2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Peatlands play a substantial role in regulating the global carbon balance and concentrations of the greenhouse gases CO2 and CH4 in the atmosphere, and are thus of utmost importance from a climate change perspective. Any changes of peatland functions due to natural or anthropogenic perturbations may result in changes in these ecosystem services. Soil microbial communities are essential drivers of biogeochemical processes, including the carbon cycle. In order to fully understand the effect of environmental perturbations on peatland functions, it is essential to understand how microbial communities are affected. The aim of the research presented in this thesis was to investigate the responses of the peat microbial communities to climate change and increased precipitation of nitrogen(N) and sulfur (S) compounds. High-throughput sequencing approaches were used to investigate the taxonomic and functional composition of microbial communities, and quantitative PCR was used to specifically target the methanogen community. Two field studies including three ombrotrophic peatlands each that differed in climatological conditions and atmospheric N and S depositions, were used to investigate and compare the effect of large- and local-scale environmental conditions on microbial communities. The results show that the variation in geo-climatological (temperature and precipitation) and atmospheric deposition conditions along the latitudinal gradient modulate the peat microbial community composition and the abundance of active methanogens to a greater extent thansite-related microhabitats. Furthermore, a tight coupling between the plant community composition of a site and the composition of its microbial community was observed, and was found to be mainly driven by plants rather than microorganisms. These co-occurrence networks are strongly affected by seasonal climate variability and the interactions between species in colder areas are more sensitive to climate change. The long-term effects of warming and increased N and S depositions on the peat microbial communities were further investigated using an 18-year in-situ peatland experiment simulating these perturbations. The impacts of each of these perturbations on the microbial community were found to either multiply or counteract one another, with enhanced N deposition being the most important factor. While the long-term perturbations resulted in a substantial shift in the taxonomic composition of microbial communities, only minor changes occurred in genome-encoded functional traits, indicating a functional redundancy. This could act as a buffer maintaining ecosystem functioning when challenged by multiple stressors, and could limit future changes in greenhouse gases and carbonexchange.

    List of papers
    1. Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia
    Open this publication in new window or tab >>Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia
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    2015 (English)In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 81, 204-211 p.Article in journal (Refereed) Published
    Abstract [en]

    Ombrotrophic raised bogs are nutrient poor acidic peatlands accumulating organic matter. They are widely spread on northern latitudes and are substantial sources of methane emissions to the atmosphere being of great concern from a climate change perspective. We investigated the methanogen community composition along microtopographic gradients within three bogs in Scandinavia, receiving different amounts of nitrogen precipitation. Methanogenic community analyses by terminal restriction fragment length polymorphism of the mcrA gene showed different profiles among the three sites, while no in- fluence of the microtopographic gradients was observed. Peat temperature and dissolved organic carbon were the major edaphic variables explaining 38% of the variation of the methanogenic community di- versity among the bogs. The family Methanoregulaceae (hydrogenotrophic methanogens) showed the largest relative proportion and highest activity in all three sites. Quantitative PCR of the mcrA gene and transcripts showed that the most northern site, receiving the lowest atmospheric nitrogen load, had significantly lower abundance and activity of methanogens (4.7 106 and 2.4 104 mcrA copies per gram of soil, respectively), compared to the most southern site (8.2 107 and 4.6 105 mcrA copies per gram of soil, respectively), receiving the highest nitrogen load. No patterns of the mcrA gene and tran- script abundances were observed along the microtopography. The results indicated that the difference in occurrence of methanogens is mainly due to geoclimatological conditions rather than site intrinsic microtopographic variation. The study further suggests that environmental changes on the site intrinsic topography will not affect the methanogenic activity, while increasing average temperatures in Scan- dinavian ombrotrophic raised bogs might contribute to an increase of the methanogenic archaeal activity resulting in an increase of methane production. 

    Place, publisher, year, edition, pages
    Elsevier, 2015
    Keyword
    Methanogenic arhcaea, mcrA gene, peatland, microtopography, T-RFLP, qPCR
    National Category
    Ecology Microbiology Environmental Sciences
    Identifiers
    urn:nbn:se:liu:diva-113846 (URN)10.1016/j.soilbio.2014.11.016 (DOI)000350524700024 ()
    Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-05-17Bibliographically approved
  • Public defence: 2017-06-09 13:00 Berzeliussalen, Linköping
    Aljabery, Firas
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Staging and tumor biological mechanisms of lymph node metastasis in invasive urinary bladder cancer2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Aim: To study the possibility of detecting lymph node metastasis in locally advanced urinary bladder cancer (UBC) treated with radical cystectomy (RC) by using preoperative positron emission tomography/computed tomography (PET/CT) and peroperative sentinel node biopsy (SNB) technique. We also investigate the clinical significance of macrophage traits expression by cancer cells, M2-macrophage infiltration (MI) in tumor stroma and the immunohistochemical expression of biomarkers in cancer cells in relation to clinicopathologic data.

    Patients and Methods: We studied prospectively 122 patients with UBC, pathological stage pT1–pT4 treated with RC and pelvic lymph node dissection (PLND) during 2005–2011 at the Department of Urology, Linköping University Hospital. In the first study, we compared the results of preoperative PET/CT and conventional CT with the findings of postoperative histopathological evaluation of lymph nodes (LNs). In the second study we investigated the value of SNB technique for detecting pathological LNs during RC in patients with UBC. W also examined the significance of the primary tumor location in the bladder in predicting the site of LN metastases, and the prognostic significance of lympho-vascular invasion (LVI) and lymph node metastasis density (LNMD) on survival. In the third study, we investigate the clinical significance of macrophage infiltration (MI) in tumor stroma and macrophage-traits expression by tumor cells. In the fourth study, we investigate the cell cycle suppression proteins p53, p21, pRb, p16, p14 ARF as well as tumors proliferative protein Ki67 and DNA repair protein ERCC1 expression in cancer cells. The results were compared with clinical and pathological characteristics and outcome.

    Results: Prior to RC, PET/CT was used to detect LN metastasis in 54 patients. PET/CT had 41% sensitivity, 86% specificity, 58% PPV, and 76% NPV, whereas the corresponding figures for conventional CT were 41%, 89%, 64%, and 77%. SNB was performed during RC in 103 patients. A median number of 29 (range 7–68) nodes per patient were examined. SNs were detected in 83 out of 103 patients (81%). The sensitivity and specificity for detecting metastatic disease by SNB varied among LN stations, with average values of 67% -90%. LNMD or ≥8% and LVI were significantly related to shorter survival. In 103 patients, MI was high in 33% of cases, while moderate and low infiltration occurred in 42% and 25% of tumors respectively. Patients with tumors containing high and moderate compared to low MI had low rate of LN metastases (P=0.06) and improved survival (P=0.06), although not at significant level. The expression of different tumor suppression proteins was altered in 47-91% of the patients. There were no significant association between cancer specific survival (CSS) and any of the studied biomarkers. In case of altered p14ARF, ERCC1 or p21, CSS was low in case of low p53 immunostaining but increased in case of p53 accumulation, although not at a significant level, indicating a possible protective effect of p53 accumulation in these cases.

    Conclusion: PET/ CT provided no improvement over conventional CT in detection and localization of regional LN metastases in bladder cancer. It is possible to detect the SN but the technique is not a reliable for perioperative localization of LN metastases; however, LVI and LNMD at a cut-off level of 8% had significant prognostic values. MI in the tumor microenvironment but not CD163 expression in tumor cells seems to be synergistic with the immune response against urinary bladder cancer. Our results further indicate that altered p53 might have protective effect on survival in case of altered p14ARF, p21, or ERCC1 indicating an interaction between these biomarkers.

    List of papers
    1. PET/CT versus conventional CT for detection of lymph node metastases in patients with locally advanced bladder cancer.
    Open this publication in new window or tab >>PET/CT versus conventional CT for detection of lymph node metastases in patients with locally advanced bladder cancer.
    Show others...
    2015 (English)In: BMC urology, ISSN 1471-2490, Vol. 15, no 1, 87- p.Article in journal (Refereed) Published
    Abstract [en]

    BACKGROUND: We studied patients treated with radical cystectomy for locally advanced bladder cancer to compare the results of both preoperative positron emission tomography/computed tomography (PET/CT) and conventional CT with the findings of postoperative histopathological evaluation of lymph nodes.

    METHODS: Patients who had bladder cancer and were candidates for cystectomy underwent preoperative PET/CT using 18-fluorodeoxyglucose (FDG) and conventional CT. The results regarding lymph node involvement were independently evaluated by two experienced radiologists and were subsequently compared with histopathology results, the latter of which were reassessed by an experienced uropathologist (HO).

    RESULTS: There were 54 evaluable patients (mean age 68 years, 47 [85 %] males and 7 [15 %] females) with pT and pN status as follows: < pT2-14 (26 %), pT2-10 (18 %), and > pT2-30 (56 %); pN0 37 (69 %) and pN+ 17 (31 %). PET/CT showed positive lymph nodes in 12 patients (22 %), and 7 of those cases were confirmed by histopathology; the corresponding results for conventional CT were 11 (20 %) and 7 patients (13 %), respectively. PET/CT had 41 % sensitivity, 86 % specificity, 58 % PPV, and 76 % NPV, whereas the corresponding figures for conventional CT were 41 %, 89 %, 64 %, and 77 %. Additional analyses of the right and left side of the body or in specified anatomical regions gave similar results.

    CONCLUSIONS: In this study, PET/CT and conventional CT had similar low sensitivity in detecting and localizing regional lymph node metastasis in bladder cancer.

    National Category
    Urology and Nephrology Cancer and Oncology
    Identifiers
    urn:nbn:se:liu:diva-120796 (URN)10.1186/s12894-015-0080-z (DOI)000359832000001 ()26294219 (PubMedID)
    Available from: 2015-08-25 Created: 2015-08-25 Last updated: 2017-05-17
    2. Radio-guided sentinel lymph node detection and lymph node mapping in invasive urinary bladder cancer: a prospective clinical study.
    Open this publication in new window or tab >>Radio-guided sentinel lymph node detection and lymph node mapping in invasive urinary bladder cancer: a prospective clinical study.
    Show others...
    2016 (English)In: BJU International, ISSN 1464-4096, E-ISSN 1464-410XArticle in journal (Refereed) Epub ahead of print
    Abstract [en]

    OBJECTIVES: To investigate the possibility of detecting sentinel lymph nodes (SNs) in patients with urinary bladder cancer (BCa) intra-operatively and whether the histopathological status of the identified SNs reflected that of the lymphatic field.

    PATIENTS AND METHODS: We studied 103 patients with BCa pathological stage T1-T4 who were treated with cystectomy and pelvic lymph node (LN) dissection during 2005-2011 at the Department of Urology, Linköping University Hospital. Radioactive tracer Nanocoll 70 MBq and blue dye were injected into the bladder wall around the primary tumour before surgery. SNs were detected ex vivo during the operation with a handheld Geiger probe (Gamma Detection System; Neoprobe Corp., Dublin, OH, USA). All LNs were formalin-fixed, sectioned three times, mounted on slides and stained with haematoxylin and eosin. An experienced uropathologist evaluated the slides.

    RESULTS: The mean age of the patients was 69 years, and 80 (77%) were male. Pathological staging was T1-12 (12%), T2-20 (19%), T3-48 (47%) and T4-23 (22%). A mean (range) number of 31 (7-68) nodes per patient were examined, totalling 3 253 nodes. LN metastases were found in 41 patients (40%). SNs were detected in 83 of the 103 patients (80%). Sensitivity and specificity for detecting metastatic disease by SN biopsy (SNB) varied between LN stations, with average values of 67% and 90%, respectively. LN metastatic density (LNMD) had a significant prognostic impact; a value of ≥8% was significantly related to shorter survival. Lymphovascular invasion (LVI) occurred in 65% of patients (n = 67) and was significantly associated with shorter cancer-specific survival (P < 0.001).

    CONCLUSION: We conclude that SNB is not a reliable technique for peri-operative localization of LN metastases during cystectomy for BCa; however, LNMD has a significant prognostic value in BCa and may be useful in the clinical context and in BCa oncological and surgical research. LVI was also found to be a prognostic factor.

    Place, publisher, year, edition, pages
    Wiley-Blackwell Publishing Inc., 2016
    Keyword
    #BladderCancer, #blcsm, cystectomy, lymph node metastasis, prognostic factors, sentinel node
    National Category
    Surgery
    Identifiers
    urn:nbn:se:liu:diva-136947 (URN)10.1111/bju.13700 (DOI)27797436 (PubMedID)
    Available from: 2017-05-01 Created: 2017-05-01 Last updated: 2017-05-17
  • Public defence: 2017-06-09 13:15 K3, Kåkenhus, Norrköping
    Krifors, Karin
    Linköping University, REMESO - Institute for Research on Migration, Ethnicity and Society. Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Arts and Sciences.
    Managing Migrant Workers: moral economies of temporary labour in the Swedish IT and wild berry industries2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Temporary migrant workers and circular migration constitute a growing global phenomenon as the management of migration becomes increasingly important to policymakers. This thesis takes academic discussions on citizenship and migration as its starting point, and examines the role of employers in terms of defining temporary migrant workers and their role in the Swedish labour market. The concept of moral economy is applied in particular to analyse the justifications and negotiations through which working conditions of migrant workers, and their role in local and transnational economies, are established and contested.

    The role of capital in migration management is studied through ethnographic fieldwork and through interviews with managers in the Swedish wild berry and IT industries; two very different industries that are, however, both shaped by particular structures of seasonal labour and international outsourcing and that increasingly rely on temporary foreign workers from Thailand and India respectively. The conceptualisation of supply chains in these industries offers a particular framework through which relations, as well as management discourses, can be analysed.

    The study explores how notions of circularity, nation, cultural difference, and transnational economic difference, are managed by private sector actors. It also explores how managers relate to public discourse and emotions in the face of global economic restructuring and changing citizenship, which situates temporary migrants as part of, yet different from, Swedish labour.

  • Public defence: 2017-06-13 09:15 Planck, Fysikhuset, Linköping
    Gudmundson, Sara
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Biology. Linköping University, Faculty of Science & Engineering.
    Species Responses to Environmental Fluctuations: impacts of food web interactions and noise color2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Species constantly experience changes in their environmental conditions owing to natural or human induces reasons. Understanding how species respond to these fluctuations are important for ecology, especially given the ongoing climate change. Empirical studies have shown that species respond differently to the same disturbance. However, our knowledge of what create these differences in the environmental response is limited and in most cases based on studies focusing on single species. In this thesis, I have taken a theoretical approach and used dynamical models to investigate how the population dynamics of species are affected by species-species interactions and environmental fluctuations.

     

    In the first paper (Paper I) I investigated how a species respond to environmental fluctuations when isolated or embedded in a food web. The study showed that species-species interactions had an effect in temporally positively autocorrelated environments (red noise) but not in uncorrelated environments (white noise). This was owing to species following their equilibrium densities in red environments which in turn enabled species-species interactions to come into play. Red environmental variables are more prominent in nature than white. Thus, these results show the importance of using a food web approach when analyzing species response to environmental fluctuations.

     

    The most commonly discussed effect of climate change is an elevated mean temperature. This shift is expected to affect the growth rate of many species. However, there is no robust theory of how we should expect species in food webs to respond to a rise in temperature. In the second paper (Paper II) I defined and studied the dynamic rate of food webs

    (DR) acting analogously to single species growth rate. I found that the higher DR the easier for species population densities to follow their equilibrium over time. Both DR and noise color changed the temporal relationship between the population and the environmental noise. Thus, it is of major importance to take the scale of time into consideration when investigating species response to environmental fluctuations.

     

    Another important factor which affect population dynamics is species spatial distributions. Dispersal between subpopulations enable individuals to rescue or prolong the time to extinction for the population seen as a whole. In the third paper (Paper III), I investigated how species in food webs respond to environments that varies both in time and space and compared the results with the one from single species. I found that single species were stabilized by an increased dispersal rate independent of the noise color. Species-species interactions had an effect for some of the species in these landscapes.

    At red asynchronous noise, one resource species in each food web had a local minimum in stability at low dispersal rate. Here, dispersal decoupled local population dynamics and prevented species from tracking their equilibriums. At high dispersal rates, all resource species and their single species counterparts were stabilized by dispersal as local patch dynamics lost its importance. Environmental noise together with the spatial dimension does seem to explain much of the stability properties of species on our planet.

     

    However, natural ecosystems are much more complex and species rich than the food web models I have used so far. Theoreticians have previously had a hard time describing stable complex systems that survive environmental fluctuations. Thus, in my fourth and last project (Paper

    IV) I investigated how species population dynamics are affected by environmental fluctuations when embedded in larger food webs. These systems were built by connecting food web modules with periodic boundary conditions (PBC). The PBC method has previously helped physicists to understand the nature of waves and particles by removing the edges in systems. I found that food web size does not have to have a negative effect on food web stability. I showed that by removing the destabilizing effect of edges it is possible to describe large stable food webs, more similar to natural ecosystems.

     

    Overall, the research presented here give new insights into species responses to environmental fluctuations. They especially highlight the importance of considering both species interactions and environmental noise color when studying population dynamics in a fluctuating environment. A food web approach is necessary when analyzing species population dynamics and planning for conservation actions, especially when studying the effects of climate change on biodiversity.

    List of papers
    1. Environmental variability uncovers disruptive effects of species interactions on population dynamics
    Open this publication in new window or tab >>Environmental variability uncovers disruptive effects of species interactions on population dynamics
    2015 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1812, 67-75 p.Article in journal (Refereed) Published
    Abstract [en]

    How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species species interactions to come into play. Our results give new insights into species response to environmental variation. They especially highlight the importance of considering both species interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

    Place, publisher, year, edition, pages
    ROYAL SOC, 2015
    Keyword
    environmental autocorrelation; environmental tracking; food webs; indirect effects; paradox of enrichment; population stability
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-122442 (URN)10.1098/rspb.2015.1126 (DOI)000362305500008 ()26224705 (PubMedID)
    Note

    Funding Agencies|Linkoping University

    Available from: 2015-11-03 Created: 2015-11-02 Last updated: 2017-05-15
  • Public defence: 2017-06-14 10:00 ACAS, A-huset, Linköping
    Aid, Graham
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Operationalizing Industrial Ecology in the Waste Sector: Roles and tactics for circular value innovation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The take-make-waste approach to resource management in human production and consumption systems is contributing to a variety of environmental and social problems worldwide. Additionally, as the world’s population and affluence increase, so do the negative impacts of poor resource management. Lifting the waste management (WM) sector into a new phase of development, which takes its lead from the ideals of Industrial Ecology and circular economy, is seen by many scholars and practitioners as one potential to assist in alleviating these impacts. While there are many studies on how more efficient inter-organizational resource management is (or could be) constructed, there are relatively few business development studies which have explored novel approaches (from roles to tactics) that WM organizations might operationalize toward more efficient resource management.

    The aim of this thesis is to contribute to the development of knowledge and understanding of how the waste management sector can operationalize more effective and efficient resource management. In approaching this aim, two research questions guided the exploration of: 1) novel roles for WM and 2) support tactics for such roles. Grounded in the broader context of Industrial Ecology (IE) and Business Development, five studies were performed. Two studies, focused on the novel roles of inter-organizational resource management and high value secondary resource extraction, were performed through literature review and interviews, and market driver analysis respectively. In exploring support tactics, two design and proof of concept studies were carried out to investigate data analysis tools for inter-organizational resource management, and one long-term action research engagement project was coordinated to study hands-on inter-organizational collaboration tactics.

    The studies highlighted that the Swedish WM sector holds some key capacities for operationalizing (and in some cases, is already developing) the novel resource management roles identified: industrial symbiosis facilitator, eco-industrial park manager, holistic facility management, and high value resource extractor. However, depending on the portfolio of services to be performed in such roles, several capacities may need to be developed or strengthened. Main opportunities seen for these roles were – staying ahead of market developments, and aligning activities with organizational goals. The main general risk related to these roles was insufficient returns on investment. Looking forward, the main enablers identified were policy leadership for more balanced market mechanisms, increasing use of external knowledge, developing long term partnerships, lobbying, stockpiling resources, and carefully crafting new business models.

    The tools developed for strategically applying external information toward the identification of opportunities within new roles showed tactical potential. However, their implementation in broader development processes has yet to be fully validated. The hands-on exploration of change oriented collaboration, highlighted collective system framing and goal setting and face-to-face interaction as key activities for inter-organizational approaches within roles such as industrial symbiosis facilitator.

    Throughout the studies, several novel roles were investigated. Each of these roles will need to be individually evaluated by directing bodies of WM organizations, and evaluated from the organization’s vision and strategy. If certain roles are chosen to be explored in more detail, they will need to be developed within full business models - addressing issues such as income structure, internal processes and capacities to be developed, and key customers. Through applying IE and business development concepts and findings, WM organizations have possibilities to translate ambitious visions into novel offerings.

    List of papers
    1. Expanding roles for the Swedish waste management sector in interorganizational resource management
    Open this publication in new window or tab >>Expanding roles for the Swedish waste management sector in interorganizational resource management
    2017 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 124, 85-97 p.Article in journal (Refereed) Published
    Abstract [en]

    Several waste management (WM) professionals see an ongoing shift in the focus of the industry, from that of atransport and treatment sector to that of a more integrated sustainable service provision and material productionsector. To further develop such transitional ambitions, WM organizations are increasingly looking toward interorganizationalresource network concepts (such as the circular economy and industrial symbiosis) as models ofhow they would like to create new value together with their customers and partners.This article aims to take a step in addressing uncertainties behind such transitions by analyzing barriers forinter-organizational resource management and in turn uncovering some potential opportunities and risks ofnovel offerings from the WM sector. Obstacles for developing innovative inter-organizational resource networkshave been identified based on studies of implementing industrial symbiosis networks. Subsequently, managingexecutives from Swedish private and public WM organizations were interviewed regarding the sector’s capacityto overcome such barriers – opportunities and risks of providing new resource management services – and howtheir organizations might approach the role of actively facilitating more resource efficient regions.Eco-Industrial park management and contracting out holistic resource management are some areas in whichthe respondents see WM organizations offering new services. In relation to such approaches, various risks (e.g.being cut out of investment benefits, or unstable supply) and opportunities (e.g. new markets and enhancedsustainability profiles) were identified. Additionally, it was seen that WM companies would need to makesubstantial changes to their business approach, becoming less dependent on flows of mixed materials forexample, if they are to become even more central value chain actors. To strengthen such approaches, it was seenthat the sector will need to find methods to strategically build strong, long term partnerships, expand upon andtake advantage of available knowledge resources (i.e. best practice technologies and regional material flows),and explore new business models (i.e. stockpiling, park management, or waste minimization). Additionally,working with sector representatives to argue for a more balanced market conditions next to primary productionshould assist the viability of new offerings in the wider market.

    Keyword
    Circular economy, Industrial symbiosis, Recycling, Business development, Green innovation
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-137456 (URN)10.1016/j.resconrec.2017.04.007 (DOI)
    Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-05-23
    2. Driving Forces and Inhibitors of Secondary Stock Extraction
    Open this publication in new window or tab >>Driving Forces and Inhibitors of Secondary Stock Extraction
    2016 (English)In: The Open Waste Management Journal, ISSN 1876-4002, E-ISSN 1876-4002, Vol. 9, 11-18 p.Article in journal (Refereed) Published
    Abstract [en]

    Even though it’s well known that our common resources are limited and that recycling is key for a sustainable future; inreality we see few examples of true recycling where virgin raw material is substituted by waste. There are endless numbers ofexamples where waste is utilized to some extent without solving the core issue: reducing the need of extracting virgin raw materials.This article analyses some of the driving forces and inhibitors of secondary stock extraction to explore why it’s so difficult establishlarge scale secondary stock extraction although suitable technologies are available. The authors discuss and suggest possible ways forreducing some of the main barriers presented.

    Keyword
    Circular economy, Economy, Recycling, Resources, Sustainability
    National Category
    Environmental Management
    Identifiers
    urn:nbn:se:liu:diva-137459 (URN)10.2174/1876400201609010011 (DOI)
    Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-05-23
    3. Looplocal - a heuristic visualization tool to support the strategic facilitation of industrial symbiosis
    Open this publication in new window or tab >>Looplocal - a heuristic visualization tool to support the strategic facilitation of industrial symbiosis
    2015 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, 328-335 p.Article in journal (Refereed) Published
    Abstract [en]

    Industrial symbiosis (IS) developments have been differentiated as self-organized, facilitated, and planned. This article introduces a tool, Looplocal, which has been built with objectives to support the strategic facilitation of IS. Looplocal is a visualization tool built to assist in 1) Simplifying the identification of regions susceptible to new industrial symbiosis facilitation activities 2) Enabling proactive and targeted marketing of potential exchanges to key actors in specific regions and 3) Assisting facilitators to assess the various strategies and consequential engagement and analysis methodologies suitable for additional IS development in specific regions. The tool compares industrial symbiosis data and estimated regional material and energy flows (on a facility level) to identify potential IS transfer information along with key stakeholder and network data. The authors have performed a proof of concept run of this tool on Sweden. In its early stages of application the method has given results seen as useful for identifying regions susceptible to the investment of symbiosis facilitators' time and resources. The material focus and customization possibilities for the tool show potential for a spectrum of potential facilitators: from waste management companies to national or regional authorities. In conjunction with long term business models, such a tool might be utilized throughout an adaptive chain of facilitation activities and aims.

    Place, publisher, year, edition, pages
    Elsevier, 2015
    National Category
    Civil Engineering
    Identifiers
    urn:nbn:se:liu:diva-137462 (URN)10.1016/j.jclepro.2014.08.012 (DOI)000356194300033 ()2-s2.0-84929966422 (ScopusID)
    Note

    QC 20150713

    Available from: 2015-07-13 Created: 2017-05-16 Last updated: 2017-05-16Bibliographically approved
    4. Improvement of aggregate cycles in Stockholm and the Baltic Region: Activities and results of the BRA initiative
    Open this publication in new window or tab >>Improvement of aggregate cycles in Stockholm and the Baltic Region: Activities and results of the BRA initiative
    2012 (English)In: Proceedings of the 8th International conference on Sustainable management of waste and recycled materials in construction, Gothenburg, Sweden, 30 May - 1 June 2012 / [ed] M. Arm, C. Vandecasteele, J. Heynen, P. Suer and B. Lind, Swedish Geotechnical Institute , 2012, 1-9 p.Conference paper (Refereed)
    Abstract [en]

    From 2009 until 2011 project BRA (Bygg-och Rivningsavfall i Stockholms Län) “Construction and Demolition (C&D) waste in Stockholm County” was coordinated from the division of Industrial Ecology, KTH. This project was focused on actively improving (from plural perspectives) the cycles of C&D (specifically non-metallic inert) materials in the region. In response to the normative aim and inter-systems complexity, a highly participative action research procedure was adopted. Through processes of network communication, workshops, a course, and an international symposium - a number of issues (such as market development, recycled product quality, greenhouse gas impacts, collaborative planning, and statistics) were prioritized, researched, and acted upon. Indicators for measuring progress in selected areas were developed and preliminary action plans created. At a final co-organized symposium Swedish delegates laid the groundwork for the establishment of a Swedish C&D recycling b ranch organization. This initiative of continued collaboration between and within sectors is seen as a vehicle for the priorities and action requirements identified in BRA to be further enabled and held in focus. Furthermore, these actors taking ownership of the process is seen as a success in accordance to the original aims and the need for further cycles of evaluation, planning, and action.

    Place, publisher, year, edition, pages
    Swedish Geotechnical Institute, 2012
    Keyword
    by-product, recycling, synergy, industrial ecology, facilitation
    National Category
    Construction Management
    Identifiers
    urn:nbn:se:liu:diva-137463 (URN)
    Conference
    WASCON 2012 – towards effective, durable and sustainable production and use of alternative materials in construction. 8th International conference on sustainable management of waste and recycled materials in construction, Gothenburg, Sweden, 30 May - 1 June 2012
    Note

    QC 20130522

    Available from: 2013-05-20 Created: 2017-05-16 Last updated: 2017-05-16Bibliographically approved
  • Public defence: 2017-06-16 10:15 Planck, Fysikhuset, Linköping
    Ektarawong, Annop
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is a theoretical study of configurational disorder in icosahedral boron-rich solids, in particular boron carbide, including also the development of a methodological framework for treating configurational disorder in such materials, namely superatom-special quasirandom structure (SA-SQS). In terms of its practical implementations, the SA-SQS method is demonstrated to be capable of efficiently modeling configurational disorder in icosahedral boron-rich solids, whiles the thermodynamic stability as well as the properties of the configurationally disordered icosahedral boron-rich solids, modeled from the SA-SQS method, can be directly investigated, using the density functional theory (DFT).

    In case of boron carbide, especially B4C and B13C2 compositions, the SA-SQS method is used for modeling configurational disorder, arising from a high concentration of low-energy B/C substitutional defects. The results, obtained from the DFT-based calculations, demonstrate that configurational disorder of B and C atoms in boron carbide is not only thermodynamically favored at high temperature, but it also plays an important role in altering the properties of boron carbide − for example, restoration of higher rhombohedral symmetry of B4C, a metal-to-nonmetal transition and a drastic increase in the elastic moduli of B13C2. The configurational disorder can also explain large discrepancies, regarding the proper- ties of boron carbide, between experiments and previous theoretical calculations, having been a long standing controversial issue in the field of icosahedral boron- rich solids, as the calculated properties of the disordered boron carbides are found to be in qualitatively good agreement with those, observed in experiments. In order to investigate the configurational evolution of B4C as a function of temperature, beyond the SA-SQS level, a brute-force cluster-expansion method in combination with Monte Carlo simulations is implemented. The results demonstrate that configurational disorder in B4C indeed essentially takes place within the icosahedra in a way that justifies the focus on lowenergy defect patterns of the superatom picture.

    The investigation of the thermodynamic stability of icosahedral carbon-rich boron carbides beyond the believed solubility limit of carbon (20 at.% C) demonstrates that, apart from B4C generally addressed in the literature, B2.5C represented by B10Cp2(CC) is predicted to be thermodynamically stable with respect to B4C as well as pure boron and carbon under high pressure, ranging between 40 and 67 GPa, and also at elevated temperature. B2.5C is expected to be metastable at ambient pressure, as indicated by its dynamical and mechanical stabilities at 0 GPa. A possible synthesis route of B2.5C and a fingerprint for its characterization from the simulations of x-ray powder diffraction pattern are suggested.

    Besides modeling configurational disorder in boron carbide, the SA-SQS method also opens up for theoretical studies of new alloys between different icosahedral boron-rich solids − for example, (B6O)1−x(B13C2)x and B12(As1−xPx)2. As for the pseudo-binary (B6O)1−x(B13C2)x alloy, it is predicted to display a miscibility gap resulting in B6O-rich and either ordered or disordered B13C2-rich domains for intermediate global compositions at all temperatures up to melting points of the materials. However, some intermixing of B6O and B13C2 to form solid solutions is also predicted at high temperature. A noticeable mutual solubility of icosahedral B12As2 and B12P2 in each other to form B12(As1−xPx)2 disordered alloy is predicted even at room temperature, and a complete closure of a pseudo-binary miscibility gap is achieved at around 900 K.

    Apart from B12(As1−xPx)2, the thermodynamic stability of other compounds and alloys in the ternary B-As-P system is also investigated. For the binary B-As system, zincblende BAs is found to be thermodynamically unstable with respect to icosahedral B12As2 and gray arsenic at 0 K and increasingly so at higher temperature, indicating that BAs may merely exist as a metastable phase. This is in contrast to the binary B-P system, in which zinc-blende BP and icosahedral B12P2 are both predicted to be stable. Owing to the instability of BAs with respect to B12As2 and gray arsenic, only a tiny amount of BAs is predicted to be able to dissolve in BP to form BAs1−xPx disordered alloy at elevated temperature. For example, less than 5% BAs can dissolve in BP at 1000 K. As for the binary As-P system, As1−xPx disordered alloys are predicted at elevated temperature − for example, a disordered solid solution of up to ∼75% As in black phosphorus as well as a small solubility of ∼1% P in gray arsenic at 750 K, together with the presence of miscibility gaps.

    The thermodynamic stability of three different compositions of α-rhombohedral boron-like boron subnitride, having been proposed so far in the literature, is investigated. Those are, B6N, B13N2, and B38N6, represented respectively by B12(N-N), B12(NBN), and [B12(N-N)]0.33[B12(NBN)]0.67. It is found that, out of these sub- nitrides, only B38N6 is thermodynamically stable from 0 GPa up to ∼7.5 GPa, depending on the temperature, and is thus concluded as a stable composition of α-rhombohedral boron-like boron subnitride.

    List of papers
    1. First-principles study of configurational disorder in B4C using a superatom-special quasirandom structure method
    Open this publication in new window or tab >>First-principles study of configurational disorder in B4C using a superatom-special quasirandom structure method
    Show others...
    2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 2, 024204Article in journal (Refereed) Published
    Abstract [en]

    Configurationally disordered crystalline boron carbide, with the composition B4C, is studied using first-principles calculations. We investigate both dilute and high concentrations of carbon-boron substitutional defects. For the latter purpose, we suggest a superatoms picture of the complex structure and combine it with a special quasirandom structure approach for disorder. In this way, we model a random distribution of high concentrations of the identified low-energy defects: (1) bipolar defects and (2) rotation of icosahedral carbon among the three polar-up sites. Additionally, the substitutional disorder of the icosahedral carbon at all six polar sites, as previously discussed in the literature, is also considered. Two configurational phase transitions from the ordered to the disordered configurations are predicted to take place upon an increase in temperature using a mean-field approximation for the entropy. The first transition, at 870 K, induces substitutional disorder of the icosahedral carbon atoms among the three polar-up sites; meanwhile the second transition, at 2325 K, reveals the random substitution of the icosahedral carbon atoms at all six polar sites coexisting with bipolar defects. Already the first transition removes the monoclinic distortion existing in the ordered ground-state configuration and restore the rhombohedral system (R3m). The restoration of inversion symmetry yielding the full rhombohedral symmetry (R (3) over barm) on average, corresponding to what is reported in the literature, is achieved after the second transition. Investigating the effects of high pressure on the configurational stability of the disordered B4C phases reveals a tendency to stabilize the ordered ground-state configuration as the configurationally ordering/disordering transition temperature increases with pressure exerted on B4C. The electronic density of states, obtained from the disordered phases, indicates a sensitivity of the band gap to the degree of configurational disorder in B4C.

    Place, publisher, year, edition, pages
    American Physical Society, 2014
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-109591 (URN)10.1103/PhysRevB.90.024204 (DOI)000339481700003 ()
    Conference
    Conference name
    Available from: 2014-08-21 Created: 2014-08-21 Last updated: 2017-05-16
    2. Configurational order-disorder induced metal-nonmetal transition in B13C2 studied with first-principles superatom-special quasirandom structure method
    Open this publication in new window or tab >>Configurational order-disorder induced metal-nonmetal transition in B13C2 studied with first-principles superatom-special quasirandom structure method
    Show others...
    2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 1, 014202Article in journal (Refereed) Published
    Abstract [en]

    Due to a large discrepancy between theory and experiment, the electronic character of crystalline boron carbide B13C2 has been a controversial topic in the field of icosahedral boron-rich solids. We demonstrate that this discrepancy is removed when configurational disorder is accurately considered in the theoretical calculations. We find that while the ordered ground state B13C2 is metallic, the configurationally disordered B13C2, modeled with a superatom-special quasirandom structure method, goes through a metal to nonmetal transition as the degree of disorder is increased with increasing temperature. Specifically, one of the chain-end carbon atoms in the CBC chains substitutes a neighboring equatorial boron atom in a B-12 icosahedron bonded to it, giving rise to a B11Ce(BBC) unit. The atomic configuration of the substitutionally disordered B13C2 thus tends to be dominated by a mixture between B-12(CBC) and B11Ce(BBC). Due to splitting of valence states in B11Ce(BBC), the electron deficiency in B-12(CBC) is gradually compensated.

    Place, publisher, year, edition, pages
    American Physical Society, 2015
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-120344 (URN)10.1103/PhysRevB.92.014202 (DOI)000357484100001 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011-4417, 330-2014-6336, 2014-4750]; CeNano at Linkoping University; LiLi-NFM; Swedish Government Strategic Research Area Grant in Materials Science

    Available from: 2015-07-31 Created: 2015-07-31 Last updated: 2017-05-16
    3. Carbon-rich icosahedral boron carbides beyond B4C and their thermodynamic stabilities at high temperature and pressure from first principles
    Open this publication in new window or tab >>Carbon-rich icosahedral boron carbides beyond B4C and their thermodynamic stabilities at high temperature and pressure from first principles
    2016 (English)In: PHYSICAL REVIEW B, ISSN 2469-9950 (print); 2469-9969 (online), Vol. 94, no 5, 054104Article in journal (Refereed) Published
    Abstract [en]

    We investigate the thermodynamic stability of carbon-rich icosahedral boron carbide at different compositions, ranging from B4C to B2C, using first-principles calculations. Apart fromB4C, generally addressed in the literature, B2.5C, represented by B10C2p (C-C), where C-p and (C-C) denote a carbon atom occupying the polar site of the icosahedral cluster and a diatomic carbon chain, respectively, is predicted to be thermodynamically stable under high pressures with respect to B4C as well as pure boron and carbon phases. The thermodynamic stability of B2.5C is determined by the Gibbs free energy G as a function of pressure p and temperature T, in which the contributions from the lattice vibrations and the configurational disorder are obtained within the quasiharmonic and the mean-field approximations, respectively. The stability range of B2.5C is then illustrated through the p-T phase diagrams. Depending on the temperatures, the stability range of B2.5C is predicted to be within the range between 40 and 67 GPa. At T greater than or similar to 500 K, the icosahedral C-p atoms in B2.5C configurationally disorder at the polar sites. By investigating the properties of B2.5C, e.g., elastic constants and phonon and electronic density of states, we demonstrate that B2.5C is both mechanically and dynamically stable at zero pressure, and is an electrical semiconductor. Furthermore, based on the sketched phase diagrams, a possible route for experimental synthesis of B2.5C as well as a fingerprint for its characterization from the simulations of x-ray powder diffraction pattern are suggested.

    Place, publisher, year, edition, pages
    AMER PHYSICAL SOC, 2016
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-131508 (URN)10.1103/PhysRevB.94.054104 (DOI)000381304300001 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011-4417, 330-2014-6336, 2014-4750]; Marie Sklodowska Curie Actions [INCA 600398]; CeNano at Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

    Available from: 2016-09-26 Created: 2016-09-23 Last updated: 2017-05-16
    4. Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics
    Open this publication in new window or tab >>Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics
    Show others...
    2016 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, no 13, 134503Article in journal (Refereed) Published
    Abstract [en]

    The elastic properties of alloys between boron suboxide (B6O) and boron carbide (B13C2), denoted by (B6O)1−x(B13C2)x, as well as boron carbide with variable carbon content, ranging from B13C2 to B4C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B6O)1−x(B13C2)x is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic properties calculations demonstrate that configurational  disorder in B13C2, where a part of the C atoms in the CBC chains substitute for B atoms in the B12 icosahedra, drastically increase the Young’s and shear modulus, as compared to an atomically ordered state, B12(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B4C to B13C2. The elastic moduli of the (B6O)1−x(B13C2)x system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B6O)1−x(B13C2)x. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B6O-rich as well as ordered or disordered B13C2-rich domains in the material prepared through equilibrium routes is predicted.

    Place, publisher, year, edition, pages
    American Institute of Physics (AIP), 2016
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-122425 (URN)10.1063/1.4944982 (DOI)000374527900023 ()27059576 (PubMedID)
    Note

    Funding agencies:Swedish Research Council (VR) [621-2011-4417, 330-2014-6336, 2011-42-59]; CeNano at Linkoping University; Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST "MISiS" [K3-2014-049]; LiLi-

    At the time for thesis presentation publication was in status: Manuscript

    Available from: 2015-11-02 Created: 2015-11-02 Last updated: 2017-05-16Bibliographically approved
    5. Thermodynamic stability and properties of boron subnitrides from first principles
    Open this publication in new window or tab >>Thermodynamic stability and properties of boron subnitrides from first principles
    2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, no 6, 064206Article, review/survey (Refereed) Published
    Abstract [en]

    We use the first-principles approach to clarify the thermodynamic stability as a function of pressure and temperature of three different alpha-rhombohedral-boron-like boron subnitrides, with the compositions of B6N, B13N2, and B38N6, proposed in the literature. We find that, out of these subnitrides with the structural units of B-12(N-N), B-12(NBN), and [B-12(N-N)](0.33)[B-12(NBN)](0.67), respectively, only B38N6, represented by [B-12(N-N)](0.33)[B-12(NBN)](0.67), is thermodynamically stable. Beyond a pressure of about 7.5 GPa depending on the temperature, also B38N6 becomes unstable, and decomposes into cubic boron nitride and a-tetragonalboron- like boron subnitride B50N2. The thermodynamic stability of boron subnitrides and relevant competing phases is determined by the Gibbs free energy, in which the contributions from the lattice vibrations and the configurational disorder are obtained within the quasiharmonic and the mean-field approximations, respectively. We calculate lattice parameters, elastic constants, phonon and electronic density of states, and demonstrate that [B-12(N-N)](0.33)[B-12(NBN)](0.67) is bothmechanically and dynamically stable, and is an electrical semiconductor. The simulated x-ray powder-diffraction pattern as well as the calculated lattice parameters of [B-12(N-N)](0.33)[B-12(NBN)](0.67) are found to be in good agreement with those of the experimentally synthesized boron subnitrides reported in the literature, verifying that B38N6 is the stable composition of a-rhombohedral-boron-like boron subnitride.

    Place, publisher, year, edition, pages
    AMER PHYSICAL SOC, 2017
    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-136168 (URN)10.1103/PhysRevB.95.064206 (DOI)000394658500001 ()
    Note

    Funding Agencies|Swedish Research Council (VR) [621-2011- 4417, 330-2014-6336, 2014-4750]; Marie Sklodowska Curie Actions [INCA 600398]; CeNano at Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]

    Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2017-05-16
  • Public defence: 2017-06-16 10:15 C3, C-huset, Linköping
    Björnsson, Andreas
    Linköping University, Department of Management and Engineering, Manufacturing Engineering. Linköping University, Faculty of Science & Engineering.
    Automated layup and forming of prepreg laminates2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Composite materials like carbon fiber-reinforced polymers (CFRPs) present highly appealing material properties, as they can combine high strength with low weight. In aerospace applications, these properties help to realize lightweight designs that can reduce fuel consumption. Within the aerospace industry, the use of these types of materials has increased drastically with the introduction of a new generation of commercial aircraft. This increased use of CFRP drives a need to develop more rational manufacturing methods.

    For aerospace applications, CFRP products are commonly manufactured from a material called prepreg, which consists of carbon fibers impregnated with uncured polymer resin. There are two dominant manufacturing technologies for automated manufacturing using prepreg, automated tape layup and automated fiber placement. These two technologies are not suitable for all types of products, either due to technical limitations or a combination of high investment costs and low productivity. Automation alternatives to the two dominant technologies have been attempted, but have so far had limited impact. Due to the lack of automation alternatives, manual manufacturing methods are commonly employed for the manufacturing of complex-shaped products in low to medium manufacturing volumes.

    The research presented in this thesis aims to explore how automated manufacturing systems for the manufacturing of complex CFRP products made from prepreg can be designed so that they meet the needs and requirements of the aerospace industry, and are suitable for low to medium production volumes. In order to explore the area, a demonstrator-centered research approach has been employed. A number of demonstrators, in the form of automated manufacturing cells, have been designed and tested with industrial and research partners. The demonstrators have been used to identify key methods and technologies that enable this type of manufacturing, and to analyze some of these methods and technologies in detail. The demonstrators have also been used to map challenges that affect the development of enabling methods and technologies.

    Automated manufacturing of products with complex shapes can be simplified by dividing the process into two steps. Thin layers of prepreg are laid up on top of each other to form flat laminates that are formed to the desired shape in subsequent forming operations. The key methods and technologies required to automate such a system are methods and technologies for automated prepreg layup, the automated removal of backing paper and the forming of complex shapes. The main challenges are the low structural rigidity and tacky nature of prepreg materials, the extensive quality requirements in the aerospace industry and the need for the systems to handle a wide array of prepreg shapes.

    The demonstrators show that it is possible to automate the manufacturing of complexshaped products using automated layup and forming of prepreg laminates. Tests using the demonstrators indicate that it is possible to meet the quality requirements that apply to manual manufacturing of similar products.

    List of papers
    1. Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
    Open this publication in new window or tab >>Composite Manufacturing: How Improvement Work Might Lead to Renewed Product Validation
    2012 (English)In: Proceedings of the 5th International Swedish Production Symposium / [ed] Mats Björkman, 2012, 505-513 p.Conference paper (Refereed)
    Abstract [en]

    High-performance polymer composites are mainly used in applications where the benefits of high strength and low weight justify the high material and manufacturing costs. Many of these applications are found today in the aerospace, space and defense industries. Most of today’s commonly used manufacturing methods within this area are highly labor intensive. Furthermore, the quality requirements from the customers require a high level of process control. The purpose of this paper is to explore how changes that are introduced in order to improve productivity in a manufacturing system are managed, particularly with regard to who takes the decision to implement a change and how a change is validated. The study is based on qualitative interviews performed at several companies that manufacture composite components for the aerospace, space and defense sectors. The findings show that the responsibility for deciding to implement a change and the need for validating it are based on many diverse and interconnected factors. Therefore, it is difficult to construct guidelines for early assessment of the scope and cost of a proposed change. Hence each individual change request must be evaluated on its own. The study also shows that the validation process can be adapted to a level that is based on the type of change. In addition, it highlights that control over process parameters in manufacturing is essential.

    Keyword
    composite manufacturing, validation, change request management
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-85268 (URN)978-91-7519-752-4 (ISBN)
    Conference
    5th International Swedish Production Symposium (SPS 2012), 6-8 November 2012, Linköping, Sweden
    Available from: 2012-11-14 Created: 2012-11-14 Last updated: 2017-05-17
    2. Automated Removal of Prepreg Backing Paper - A Sticky Problem
    Open this publication in new window or tab >>Automated Removal of Prepreg Backing Paper - A Sticky Problem
    2013 (English)In: Proceedings of the SAE 2013, Aerotech Congress and Exhibition, 24th-26th September 2013, Montreal,Canada, 2013Conference paper (Refereed)
    Abstract [en]

    Automated solutions for manufacturing composite products based on prepreg often imply Automatic Fiber Placement or Automatic Tape Laying. These systems are generally associated with huge investments. For certain manufacturing applications it is interesting to investigate alternatives to find simpler and less costly automation. One example of an automated system could be the use of a standard industrial robot to pick single prepreg plies from an automated cutting machine and stack them to form a plane laminate. This paper is based on a case illustrating a product from the aircraft manufacturing industry. The case will demonstrate a pick and place concept on a general level and illustrate challenges that must be solved. The challenge selected to be the main focus for this paper is an automated process for backing paper removal. A literature review of different gripping technologies reveals several interesting technologies, and the most promising are tested for backing paper removal. The tests show that an automated removal process can be designed by using standard vacuum grippers in combination with mechanical clamping grippers. In order to lift the backing paper with a vacuum gripper an initial separation between the backing paper and prepreg is needed. This separation is most easily mechanically induced by bending the material. The proposed solution for automatic backing paper removal can be integrated in a manufacturing cell for manufacturing of the studied product.

    Keyword
    composite manufacturing, automation, prepreg, gripping technology
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-99344 (URN)10.4271/2013-01-2289 (DOI)
    Conference
    SAE 2013 Aerotech Congress and Exhibition, September 24-26, 2013, Montréal, Quebec, Canada
    Note

    SAE Technical Paper 2013-01-2289

    Available from: 2013-10-16 Created: 2013-10-16 Last updated: 2017-05-17Bibliographically approved
    3. Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
    Open this publication in new window or tab >>Automation of Composite Manufacturing Using Off-the-shelf Solutions, Three Cases from the Aerospace Industry
    2015 (English)In: Proceedings of the 20th International Conference on Composite Materials, 2015Conference paper (Other academic)
    Abstract [en]

    With an increased use of composite materials follows a need for rational, cost-efficient manufacturing processes. This paper explores how off-the-shelf solutions, developed for other purposes than composite manufacturing, can be used to build systems for automated composite manufacturing. Three demonstrators, each of them dealing with a specific type of material and all of them representing different manufacturing technologies for automated composite manufacturing, are presented and analyzed to find aspects that affect the ability to use off-the-shelf solutions. The three demonstrators target low to medium manufacturing volumes of complex products and they have been developed in collaboration with industrial partners within the aerospace industry. The conclusions drawn from the development of the demonstrators are that it is technically feasible to use off-the-shelf solutions in the three cases while adhering to the high quality standards of the industry. Furthermore three groups of aspects, quality aspects, product aspects and system aspects, which affect the ability to use off-the-shelf solutions for automated composite manufacturing, are identified.

    Keyword
    composite manufacturing, automation, off-the-shelf, aerospace
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-120300 (URN)
    Conference
    ICCM20 - The 20th International Conference on Composite Materials, 19-24th July 2015, Copenhagen Denmark
    Available from: 2015-07-27 Created: 2015-07-27 Last updated: 2017-05-17
    4. Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
    Open this publication in new window or tab >>Low-cost Automation for Prepreg Handling - Two Cases from the Aerospace Industry
    2016 (English)In: SAE International Journal of Materials and Manufacturing, ISSN 1946-3979 (print), 1946-3987 (online), Vol. 9, no 1Article in journal (Refereed) In press
    Abstract [en]

    With an increased use of composite materials within the aerospace industry follows a need for rational and cost-effective methods forcomposite manufacturing. Manual operations are still common for low to medium manufacturing volumes and complex products.Manual operations can for example be found in material handling, when picking prepreg plies from a cutter table and stacking them toform a plane laminate in preparation for a subsequent forming operation. Stacking operations of this kind often involves a greatnumber of different ply geometries and removal of backing paper and other protecting materials like plastic. In this paper two differentdemonstrator cells for automated picking of prepreg plies and stacking of plane laminates are presented. One demonstrator is utilizinga standard industrial robot and an advanced end-effector to handle the ply variants. The other demonstrator is using a dual arm robotwhich allow for simpler end-effector design. In combination with a previously developed system for automated removal of backingpapers both systems have shown to be capable of automatically picking prepreg plies from a plane surface and stack them to generate aflat multistack laminate. The dual arm approach has shown advantageous since it result in simpler end-effector design and a successivelay down sequence that result in good adhesion between the plies in the laminate.

    Place, publisher, year, edition, pages
    Warrendale, USA: SAE International, 2016
    Keyword
    Composite, Manufacturing, Automation, Low-cost, Prepreg
    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-121602 (URN)10.4271/2015-01-2606 (DOI)
    Available from: 2015-09-28 Created: 2015-09-28 Last updated: 2017-05-17Bibliographically approved
    5. Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
    Open this publication in new window or tab >>Robot-Forming of Prepreg Stacks ‐ Development of Equipment and Methods
    Show others...
    2016 (English)In: Proceedings of the 17th European Conference on Composite Materials (ECCM17), 2016Conference paper (Other academic)
    Abstract [en]

    Within the aerospace industry the manufacturing of composite components with complex shapes, such as spars, ribs and beams are often manufactured using manual layup and forming of prepreg material. Automated processes for prepreg layup and efficient forming techniques like vacuum forming are sometimes difficult to employ to these type of products due to technical limitations. This paper describes the development of tools and the forming sequence needed to automate sequential forming of a complex shape using an industrial robot. Plane prepreg stacks are formed to the final shape using a dual-arm industrial robot equipped with rolling tools. Tests show that the developed tools and the employed sequence can be used to form stacks to the desired shape with acceptable quality.

    National Category
    Production Engineering, Human Work Science and Ergonomics
    Identifiers
    urn:nbn:se:liu:diva-129925 (URN)
    Conference
    ECCM17 - 17th European Conference on Composite Materials 26-30th June 2016, Munich, Germany
    Available from: 2016-07-01 Created: 2016-07-01 Last updated: 2017-05-17Bibliographically approved
  • Public defence: 2017-06-16 13:00 I:101, Hus I, Linöping
    Carlsson, Jessica
    Linköping University, Department of Behavioural Sciences and Learning, Education, Teaching and Learning. Linköping University, Faculty of Arts and Sciences.
    Children’s early mathematics learning and development: Number game interventions and number line estimations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Children’s early mathematics learning and development have become a topic of increasing interest over the past decade since early mathematical knowledge and skills have been shown to be a strong predictor of later mathematics performance. Understanding how children develop mathematical knowledge and skills and how they can be supported in their early learning could thus prove to be a vital component in promoting learning of more formal mathematics.

    In light of the above, with this thesis I sought to contribute to an increased understanding of children’s early mathematics learning and development by examining effects of playing different number games on children’s number knowledge and skills, and by investigating children’s representations of numbers on number line tasks.

    Two number game intervention studies were performed, and effects of three different number game conditions (linear number, circular number and nonlinear number) were investigated by examining 5- and 6-year-old children’s pre- and posttest performance on different numerical tasks. The findings indicate that playing number games in general support children’s development of number knowledge and skills, where the specific learning outcomes are affected differently depending on the type of number game utilized.

    To elucidate children’s representations of numbers, their performance on two different  umber line tasks have been analyzed using a latent class modeling approach. The results reveal that there is a heterogeneity in 5- and 6-year-old children’s number line estimations and subgroups of children showing different estimation patterns were distinguished. In addition, it is shown that children’s number line estimations can be associated to their number knowledge as well as to task specific aspects.

    The findings presented in this thesis contribute to the discussion of the value of selecting game activities in a conscious way to support children’s early mathematics learning and development. They also add to the discussion regarding the number line task and how children’s number line estimations can be analyzed and interpreted.

    List of papers
    1. Playing number board games supports 5-year-old children’s early mathematical development
    Open this publication in new window or tab >>Playing number board games supports 5-year-old children’s early mathematical development
    2016 (English)In: Journal of Mathematical Behavior, ISSN 0732-3123, E-ISSN 1873-8028, Vol. 43, 134-147 p.Article in journal (Refereed) Published
    Abstract [en]

    The study examined effects of playing number games (linear number board game, circular number board game, and nonlinear numerical activities) on the development of number knowledge and early arithmetic. A passive control group was also included in the design. 114 5-year-old preschool children participated. Four tasks (number line estimation, counting, naming Arabic numbers, and arithmetic calculation) were used as dependent measures. Children assigned to an intervention participated in six 10-min sessions during a period of three weeks. Children playing the linear number board game improved their performance on the number line estimation task, while children playing the other games did not. Furthermore, children playing the linear number board game showed a substantial enhancement of their calculation performance. The positive effects of playing linear number board games support the representational mapping hypothesis. The finding concerning calculation provides support to the assumption that a linear representation is important for early arithmetical learning.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Linear number board games, Intervention, Preschoolers, Number line estimation, Arithmetic
    National Category
    Learning Mathematics Pedagogy
    Identifiers
    urn:nbn:se:liu:diva-137476 (URN)10.1016/j.jmathb.2016.07.003 (DOI)
    Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2017-05-17Bibliographically approved
  • Public defence: 2017-06-16 13:00 K2, Kåkenhus, Norrköping
    Machat-From, Laura
    Linköping University, Department of Social and Welfare Studies, Division Ageing and Social Change. Linköping University, Faculty of Arts and Sciences.
    Identity, Old(er) Age and Migrancy: A Social Constructionist Lens2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    ldentity research in relation to ethnicity and migration has tended to focus an younger people whilst identity research in relation to ageing and old(er) age has not focused an migrants. This inadvertent mutual neglect has led to a lack of identity research that examines the identity categories of old(er) age and migrancy together, a lacuna that this dissertation aims to redress. This dissertation departs from a social constructionist understanding of identity as situationally accomplished in the interplay between how one defines oneself (internally) and how others define one (externally). The questions raised by this perspective and addressed in this dissertation are: When (in what situations) and in relation to whom do old(er) age and migrancy (respectively) seem to become meaningful for identification? How do the identity categories of old(er) age and migrancy seem to be negotiated? The empirical material consists of in-depth interviews with 24 older migrants (13 men, 11 women) aged between 55 and 79 who have been living in Sweden for 18 to 61 years. Interviewees come from 12 different countries that vary in perceived cultural distance from Sweden. The findings suggest that identifications with old(er) age and migrancy seem to be dynamic and flexible rather than necessarily permanently meaningful, thus gaining meaning in specific situations and in relation to particular Others. External definitions furthermore do not always seem to match with internal ones. Regardless of how old(er) age and migrancy are constructed, they seem to be negotiable. This dissertation thus contributes to identity research by studying old(er) age and migrancy together and furthermore sheds light onto how the social constructionist lens allows us to see variability where stability otherwise would be presumed.

  • Public defence: 2017-06-16 13:15 ACAS, A-huset, Linköping
    Onufrey, Ksenia
    Linköping University, Department of Management and Engineering, Project Innovations and Entrepreneurship. Linköping University, Faculty of Science & Engineering.
    Enabled by the past: understanding endogenous innovation in mature industries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mature industries have played and still play a crucial role in national and world economies. To survive and retain competitiveness, they need to innovate, as innovation is the driver of economics growth and industrial transformation. However, existing research does not provide sufficient explanation of how innovation in mature industries can be enabled based on resources and internal development logic of those industries, i.e. endogenously. Some previous studies focused on incremental innovation patterns, which led to an underestimation of innovation potential of mature industries. Other studies acknowledged a high innovation potential of mature industries, but failed to explain how, through what mechanisms, industry-endogenous logic can bring about major innovations.

    Therefore, the purpose of this thesis is to systematically address, explain and conceptualize endogenous industry- innovation and its driving mechanisms in mature industries. To achieve this purpose, three main issues are addressed. First, the thesis investigates and conceptualizes the notion of industry endogenous innovation mechanisms based on the path dependency theory. Second, the thesis addresses strategic choices and actions by established companies that are rooted in the industry endogenous mechanisms and result in highly innovative outcomes. Third, the thesis systematically analyses different aspects of radicalness of innovations resulting from industry endogenous mechanisms.

    The thesis represents a qualitative, embedded case study with two main industry cases, i.e. the global lighting industry and the Swedish pulp and paper industry. The lighting industry and its sub-cases in the form of specific lighting technologies have been studied via the analysis of patents of leading lighting manufacturers, archival and secondary data sources as well as interviews with different types of actors in the industry. The pulp and paper industry and its sub-cases in the form of innovation initiatives have been studied with the help of interviews with leading manufacturers and research institutes, as well the analysis of annual reports and secondary data sources. The outcomes of the study are presented in the form of the thesis cover paper and five appended papers.

    The results show that innovations of any magnitude can be endogenously developed in mature industries. At the industry level, endogenous innovation is driven by innovation mechanisms that can be conceptualized as reactive sequences and self-reinforcing mechanisms. At the level of individual companies, the exploitation strategy corresponds to the logic of endogenous innovation mechanisms by enabling highly innovative outcomes and building on a wide range of resources available in the industry. The endogenous character of innovation mechanisms imposes certain limitations on the radicalness of the outcomes in the form of trade-offs in terms of how many and what particular aspects can be radically new at once.

    With these results, the thesis contributes to a more balanced overall understanding of innovation potential of mature industries and allows shifting the focus of discussion from whether mature industries can develop radical innovation to when and under what conditions they can succeed in this process. The results of the thesis also suggest several recommendations for managers in established companies with regard to how they can they can take advantage of industry endogenous innovation mechanisms.

    List of papers
    1. Is one path enough? Multiple paths and path interaction as an extension of path dependency theory
    Open this publication in new window or tab >>Is one path enough? Multiple paths and path interaction as an extension of path dependency theory
    2014 (English)In: Industrial and Corporate Change, ISSN 0960-6491, E-ISSN 1464-3650, Vol. 23, no 5, 1261-1297 p.Article in journal (Refereed) Published
    Abstract [en]

    To explain the development of multi-technology companies and industries where several alternative technologies co-exist and interact over long periods, this article suggests an extension of path dependency theory by providing a conceptualization of the path notion that incorporates the theoretical possibility of multiple paths and path interaction. The conceptualization is applied to a patent study of three leading companies in the lighting industry: General Electric, Osram/Siemens, and Philips. The study shows technology development patterns that are characterized by strong persistence, both within each path and across the whole technology field. These results demonstrate that multiple technological paths can co-exist in companies and industries, characterized by simultaneous long-term presence of several technologies. In such cases, path interaction takes place both between co-existing paths and when new, radically different paths are created. Although further studies are needed to identify the underlying self-reinforcing mechanisms, there is a clear indication that technological path dependency is not restricted to unitary progression patterns, as implied by previous conceptualizations.

    Place, publisher, year, edition, pages
    Oxford University Press, 2014
    National Category
    Economics and Business Other Engineering and Technologies not elsewhere specified
    Identifiers
    urn:nbn:se:liu:diva-102614 (URN)10.1093/icc/dtt040 (DOI)000343321100005 ()
    Available from: 2013-12-17 Created: 2013-12-17 Last updated: 2017-03-27
    2. Endogenous sources of path generation in a path dependent industry
    Open this publication in new window or tab >>Endogenous sources of path generation in a path dependent industry
    2016 (English)In: Technology Analysis & Strategic Management, ISSN 0953-7325, E-ISSN 1465-3990Article in journal (Refereed) Published
    Abstract [en]

    This paper investigates and conceptualises industry endogenous sources of innovation in a context of path dependency. With an embedded case study of the mature multi-technology lighting industry, it considers two cases of technology generation (fluorescent lamps and light-emitting diodes) that have occurred under the dominance of established incandescent technology. The results demonstrate the existence of common driving forces (variety of performance criteria and variety of lighting applications) behind the development of the existing path and the generation of two new paths. Such common driving forces indicate the existence of a reactive sequence or a logical causal relationship between the existing and the new paths, which serve as an enabling mechanism in endogenous path generation.

    Keyword
    industry endogenous innovation, lighting industry, Path dependency, path generation, reactive sequences
    National Category
    Computer Science Other Engineering and Technologies not elsewhere specified Computer Systems Computer Engineering Information Systems, Social aspects
    Identifiers
    urn:nbn:se:liu:diva-136098 (URN)10.1080/09537325.2016.1268683 (DOI)
    Available from: 2017-03-27 Created: 2017-03-27 Last updated: 2017-04-03Bibliographically approved
    3.