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  • Public defence: 2017-03-31 13:15 K1, Kåkenhus, Norrköping
    Åkerlund, Nina
    Linköping University, Department of Social and Welfare Studies, Social Work. Linköping University, Faculty of Arts and Sciences.
    Barns relationer i våldets närhet: Respons, positioner och möjligheten till barns röst2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim with this thesis is to explore children’s perspectives on responses when experiencing intimate partner violence (IPV). Special focus is on the children’s own responses, as well as the actions and reactions of their siblings, grandparents and other adults in their proximity. Through this, the objective is to explore the significance of the relational setting for children exposed to IPV. This thesis is inspired by the sociology of childhood and the sociology of personal life. It has also employed positioning theory. The thesis consists of four papers. In article I, the use of children’s voices in qualitative research with children exposed to IPV is discussed. The following empirical papers, who are based on analyses of interviews with 20 children (11–19 years of age), explore children’s experiences of responses when exposed to violence. The children’s stories suggest that there often are people who know about the violence and the articles analyse how children position themselves in their stories, but also how they are positioned by their siblings (article II), their grandparents (article IV) and other adults (article III). Children exposed to IPV may experience the violence differently and respond to the abuse in a variety of ways. Similarly, individuals in the children’s relational setting may respond to the abused children differently, which can be understood on the basis that relationships are surrounded by different expectations and that responses are interactional phenomenon – individuals close to the children partly adapt their response to how the children react to the abuse. Children describe responses from individuals in their relational setting as either helpful or unhelpful, depending on how responsive, accessible and intimate the individual is perceived. The thesis also suggests that the children have a limited room for maneuverer and only a few positions available for them in the aftermath of violence. The primary attainable positions to the children experiencing IPV are the ones as ‘vulnerable victim’, ‘vulnerable but competent actor’, and ‘adult-like and caregiving actor’. A key factor for children to receive helpful responses is being positioned as vulnerable victims and as competent actors simultaneously.

    List of papers
    1. Caring or Vulnerable Children? Sibling Relationships When Exposed to Intimate Partner Violence
    Open this publication in new window or tab >>Caring or Vulnerable Children? Sibling Relationships When Exposed to Intimate Partner Violence
    2017 (English)In: Children andamp; Society, ISSN 09510605Article in journal (Refereed) Published
    Abstract [en]

    Drawing on qualitative interviews with the children about how they and their siblings have responded tointimate partner violence, this paper explores processes of victim positioning. In their narratives, somechildren positioned themselves in line with notions of vulnerable victims, while others positioned them-selves as caregivers or changed their positions vis-a-vis their siblings. In their stories, they assigned andassumed positions in interaction with their siblings. Receiving sibling support and care was in the nar-ratives related to the quality of the sibling relationship, the shared experiences of violence and the ageorder.

    Place, publisher, year, edition, pages
    West Sussex: Wiley-Blackwell, 2017
    Keyword
    children, intimate partner violence, positioning, response, siblings
    National Category
    Sociology (excluding Social Work, Social Psychology and Social Anthropology) Social Work Nursing Ethnology
    Identifiers
    urn:nbn:se:liu:diva-134902 (URN)10.1111/chso.12215 (DOI)
    Available from: 2017-03-01 Created: 2017-03-01 Last updated: 2017-03-01Bibliographically approved
    2. Children’s voices in research with children exposed to intimate partner violence: A critical review
    Open this publication in new window or tab >>Children’s voices in research with children exposed to intimate partner violence: A critical review
    2017 (English)In: Nordic Social Work Research, ISSN 2156-857X, E-ISSN 2156-8588, Vol. 7, no 1, 42-53 p.Article in journal (Refereed) Published
    Abstract [en]

    This article discusses how qualitative research with children exposed to intimate partner violence deals with methodological issues of children’s voices. Violence researchers argue for the need to see children as competent social actors, di erentiate between groups of children, attending to adult– child asymmetry in research and acknowledging children’s individual experiences. However, little is said about how children’s voices are produced in their local, cultural and societal contexts. There is also an ignorance of the politics of representation, which may hamper the development of ethically responsible research on children exposed to intimate partner violence. 

    Place, publisher, year, edition, pages
    Routledge, 2017
    Keyword
    Children’s voices, child abuse, intimate partner violence, reflexivity
    National Category
    Social Work Social Sciences Interdisciplinary
    Identifiers
    urn:nbn:se:liu:diva-125989 (URN)10.1080/2156857X.2016.1156019 (DOI)
    Available from: 2016-03-10 Created: 2016-03-10 Last updated: 2017-03-17Bibliographically approved
    3. Children and violence interactions: Exploring intimate partner violence and children's experiences of responses.
    Open this publication in new window or tab >>Children and violence interactions: Exploring intimate partner violence and children's experiences of responses.
    2016 (English)In: Child Abuse Review, ISSN 0952-9136, E-ISSN 1099-0852Article in journal (Refereed) Published
    Abstract [en]

    While there is a growing research interest in the experiences of children exposed to intimate partner violence (IPV), the role of children's social networks, other than the role of mothers, has been little discussed. The aim of this article is to study older children's stories of how they, and the adults in their social networks, respond to IPV. More specifically, we are interested in how older children describe both their own responses when exposed to IPV and responses from adults. This article focuses on the narratives of older children since they are often in a liminal position between adulthood and childhood, which may be consequential for their and others’ responses to violence. The article shows that responses are interactional and that children's responses affect how adults respond. Our analysis suggests that adults are positioning children as either adult‐like and competent or vulnerable, and this impacts significantly on the support that they receive. In our data, there are, however, also examples of middle ways where children are positioned as vulnerable yet capable. This seems linked to children's abilities to communicate their own needs. Although the study sample is limited, our results point to the significance of gender for how children respond. Copyright © 2016 John Wiley and Sons, Ltd. ‘Focuses on the narratives of older children since they are often in a liminal position between adulthood and childhood’ Key Practitioner Messages Social network responses can be crucial to the disclosure, ending and continuation of IPV. Awareness of exposure to IPV does not automatically result in responses that are beneficial to children's wellbeing. Professionals need to be better at communicating with the social network. Children's responses are contextual and protection and support should be designed according to children's individually varying needs. ‘Awareness of exposure to IPV does not automatically result in responses that are beneficial to children's wellbeing’ (PsycINFO Database Record (c) 2016 APA, all rights reserved)

    Place, publisher, year, edition, pages
    West Sussex: John Wiley & Sons, 2016
    Keyword
    children witnessing violence; dialogue; intimate partner violence; domesticviolence; responses; social networks
    National Category
    Social Work
    Identifiers
    urn:nbn:se:liu:diva-134904 (URN)10.1002/car.2438 (DOI)
    Available from: 2017-03-01 Created: 2017-03-01 Last updated: 2017-03-16Bibliographically approved
  • Public defence: 2017-04-06 13:15 ACAS, B-huset, Linköping
    Öhlund, Sten-Erik
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Arts and Sciences.
    Interoperability Capability to interoperate in a shared work practice using information infrastructures: studies in ePrescribing2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The ability to interoperate between systems, people, and organizations is considered an important issue within eHealth in order to deliver patient centered care. The achieving and improving of interoperability is a complex undertaking involving the evolution of an information infrastructure, sharing of knowledge and resources, governance of the interoperation between organizations, people and work practices, and handling of economic and legal matters.

    This thesis contributes with practical knowledge on improving interoperability, based on active participation in and empirical studies of improving interoperability in ePrescribing. A case study describes and analyzes the evolution of ePrescribing in Sweden since the early pioneering years in 1980s, its growth and consolidation before the reregulation of the pharmacy market in 2009. Apractical theory on ePrescribing is presented. A unique field experimental study measuring improvement of interoperability in ePrescribing, before and after a major intervention to improve the quality of ePrescriptions between 2004 and 2009 is presented.

    Furthermore, a practical theory on interoperation and interoperability is presented. Interoperability is seen as the exercised capability of organizations through their agents to interoperate in a shared work practice in an effective, efficient, and satisfactory manner based on a common ground in a mediated, prescriptive, and non-personal communicative setting using an information infrastructure for mediating interoperation.

  • Public defence: 2017-04-07 10:15 TEMCAS, T building, Linköping
    Upadhyaya, Prabhat
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Centre for Climate Science and Policy Research, CSPR.
    National Appropriateness of International Climate Policy Frameworks in India, Brazil, and South Africa2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    How does the international climate policy frameworks influence the domestic institutional responses to climate mitigation in emerging economies? And how, in turn, do domestic institutions and politics in emerging economies influence the fate of international climate policy frameworks? The thesis provides answers to these questions by studying domestic engagements with Nationally Appropriate Mitigation Actions in three emerging economies – India, Brazil, and South Africa. The thesis specifically studies how these engagements were influenced by the domestic institutional context provided by national climate policy, norms, and institutional capacity in the three countries. Drawing upon the variations in the engagements with nationally appropriate mitigation actions, made visible by use of the policy cycle as a heuristic device, the thesis informs the implementation of another nascent, yet prevalent, international climate policy framework – Nationally Determined Contributions. The thesis identifies how engagements with nationally appropriate mitigation actions varied in India, Brazil, and South Africa in agenda-setting, policy formulation, decision-making, implementation, and evaluation. In cases where international support is considered crucial for taking mitigation actions, external factors such as lack of clarity on definitional aspects and availability of international support can hamper the prospects of such frameworks at the agenda-setting and policy formulation stages. Efforts to engage with these frameworks under this uncertainty are held back by non-decisions, overriding national climate policy, as well as by uneven inter-ministerial coordination. The thesis argues that successful implementation of upcoming Nationally Determined  Contributions will be influenced by a country’s ability to align them with its national climate policy, localization of the transnational norms, and the extent to which efforts to enhance institutional capacity for  coordinating the implementation of national climate policy are made. In sum, the effective implementation of International Climate Policy Frameworks will be dependent on the willingness of the state to  provide oversight and coordination, and clarity on the availability of international support.

    List of papers
    1. Developments in national climate change mitigation legislation and strategy
    Open this publication in new window or tab >>Developments in national climate change mitigation legislation and strategy
    2013 (English)In: Climate Policy, ISSN 1469-3062, E-ISSN 1752-7457, Vol. 13, no 6, 649-664 p.Article in journal (Refereed) Published
    Abstract [en]

    The results are presented from a survey of national legislation and strategies to mitigate climate change covering almost all United Nations member states between 2007 and 2012. This data set is distinguished from the existing literature in its breadth of coverage, its focus on national policies (rather than international pledges), and on the use of objective metrics rather than normative criteria. The focus of the data is limited to national climate legislation and strategies and does not cover subnational or sectoral measures. Climate legislation and strategies are important because they can: enhance incentives for climate mitigation; provide mechanisms for mainstreaming; and provide a focal point for actors. Three broad findings emerge. First, there has been a substantial increase in climate legislation and strategies between 2007 and 2012: 67% of global GHG emissions are now under national climate legislation or strategy compared to 45% in 2007. Second, there are substantial regional effects to the patterns, with most increases in non-Annex I countries, particularly in Asia and Latin America. Third, many more countries have adopted climate strategies than have adopted climate legislation between 2007 and 2012. The article concludes with recommendations for future research.Policy relevance The increase in climate legislation and strategy is significant. This spread suggests that, at the national level, there is some movement in reshaping climate governance despite the relatively slow pace of global negotiations, although the exact implications of this spread require further research on stringency of actions and their implementation. Asia and Latin America represent the biggest improvements, while OECD countries, which start from a high base, remain relatively stagnant. Implications of regional patterns are further refined by an analysis by emissions, which shows that some areas of low levels of legislation and strategy are also areas of relatively low emissions. A broad trend toward an emphasis on strategies rather than legislation, with the significant exception of China, calls for enhanced research into the practical impact of national non-binding climate strategies versus binding legislation on countries' actual emissions over time.

    Place, publisher, year, edition, pages
    London: Taylor & Francis, 2013
    Keyword
    Climate change, domestic policy instruments, national policies, policy measures, public policy
    National Category
    Climate Research
    Identifiers
    urn:nbn:se:liu:diva-99869 (URN)10.1080/14693062.2013.845409 (DOI)000325845100001 ()
    Projects
    GoVNAMAs - Phase I
    Funder
    Swedish Energy Agency
    Available from: 2013-10-22 Created: 2013-10-22 Last updated: 2017-03-14Bibliographically approved
    2. Aligning Climate Policy with National Interest: Disengagements with Nationally Appropriate Mitigation Actions in South Africa
    Open this publication in new window or tab >>Aligning Climate Policy with National Interest: Disengagements with Nationally Appropriate Mitigation Actions in South Africa
    2016 (English)In: Journal of Environmental Policy and Planning, ISSN 1523-908X, E-ISSN 1522-7200, Vol. 18, no 4, 463-481 p.Article in journal (Refereed) Published
    Abstract [en]

    Nationally Appropriate Mitigation Actions (NAMAs) were proposed as a policy framework that could provide middle ground for meeting both the development and mitigation objectives in developing countries. While South Africa engaged actively with the NAMA terminology in the United Nations Framework Convention on Climate Change negotiations, its engagement at the domestic level has been rather lacklus- tre. This presents an interesting paradox. The paper studies the interplay of international norms embodied in NAMAs with South Africa’s domestic policy process. Disengagement and contestation around NAMAs in South Africa is played out at three stages: decision- making stage where the symptoms surrounding this contestation first emerge; policy for- mulation stage where NAMAs have to not only align with the National Development Plan but also compete with a predilection for domestically familiar terminology of flagships under the national climate policy; and finally the broader agenda-setting stage of policy process, where NAMAs have to prove useful in not only pursuing the developmental state agenda but also in tackling the underlying material factors that represent country’s economic dependency on fossil fuels. NAMAs faced combined resistance from ideas and interests in various degrees at all these stages resulting in their disengagement.

    Place, publisher, year, edition, pages
    Taylor & Francis Group, 2016
    Keyword
    Climate Policy, South Africa, Domestic Politics, International Relations, Policy process, NAMA
    National Category
    Climate Research Political Science (excluding Public Administration Studies and Globalization Studies)
    Identifiers
    urn:nbn:se:liu:diva-124580 (URN)10.1080/1523908X.2016.1138402 (DOI)000381299800005 ()
    Projects
    GoverningNAMAs: Phase 2 -- Enhancing design and support for low-carbon trajectories
    Funder
    Swedish Energy Agency, P35462-2
    Note

    Funding agencies: Swedish Energy Agency (Energimyndigheten) [P35462-2]

    Available from: 2016-02-04 Created: 2016-02-04 Last updated: 2017-03-14Bibliographically approved
  • Public defence: 2017-04-07 13:00 Hasselquistsalen, Hus 511, Medicinska Fakulteten, Linköping
    Veenstra, Cynthia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    The receptor tyrosine kinase Met and the protein tyrosinephosphatase PTPN2 in breast cancer2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Breast cancer is the most common form of cancer in women worldwide and the second leading cause of cancer death. It is a heterogeneous disease and is subdivided into different subtypes, all with different treatment responses and survival outcomes. Luminal breast cancers are characterised by the expression of oestrogen receptor and generally have a good prognosis. More aggressive tumours are marked by the presence of growth stimulating receptor tyrosine kinase HER2 (HER2-like breast cancer) or the absence of oestrogen receptor, progesterone receptor, and HER2 (triple-negative breast cancer,TNBC). The latter is the most aggressive form and is difficult to treat due to lack of treatment targets.

    This thesis aimed to explore possible prognostic and predictive biomarkers in different subtypes and study their role in breast cancer. To this aid, breast cancer tumours of pre- and post-menopausal patients enrolled in two cohorts were analysed for gene copy numbers and expression of proteins involved in cell proliferation. Gene copy numbers of receptor tyrosine kinases MET and EGFR, Met’s ligand HGF, and protein tyrosine phosphatase PTPN2 were determined by droplet digital PCR or quantitative PCR in both cohorts. Met, phosphorylated Met (pMet), HGF, and PTPN2 protein expression levels were analysed with immunohistochemical staining in the pre-menopausal cohort. Moreover,the role of the aforementioned proteins was investigated in breast cancer cell lines. Amplification of MET, HGF, and EGFR in breast tissues was found to be low (5-8%). These three genes, all located on chromosome 7, were found to be strongly correlated with eachother and to be associated with shortened distant recurrence-free survival. High protein expression of Met, pMet, and HGF was found in 33%, 53%, and 49% of the breast tumours. MET and EGFR were found to be more often amplified in TNBC disease, correlating with worse survival. Moreover, stromal expression of HGF was associated with shorter survival in TNBC. EGF stimulation in TNBC cell line MDA-MB-468 led to inhibited cell proliferation and migration. Partial knockdown of EGFR caused TNBC cells to proliferate and migrate more upon EGF treatment, mirroring EGFR inhibitor resistance. Knockdown of Met had in part the opposite effects, indicating that Met inhibitors might be useful in the treatment of TNBC. The increase in proliferation and migration upon EGFR depletion could be counteracted with simultaneous knockdown of EGFR and Met, indicating that dual inhibition of these proteins might be a future treatment option in TNBC.

    Copy loss of PTPN2 was reported in 15% of the cases in both pre- and post-menopausal cohorts. Low cytoplasmic PTPN2 protein expression was found in half of the cases. Loss of PTPN2 gene or protein was associated with a shorter distant recurrence-free survival in Luminal A and HER2-positive tumours, not in TNBC, suggesting a subtype-related prognostic value of PTPN2. Subtype relevance of PTPN2 was further implied by in vitro analyses. Whereas PTPN2 knockdown had no observed effect on TNBC cell lines, knockdown in the Luminal A cell line MCF7 inhibited Met phosphorylation and promoted phosphorylation of Akt, a key regulator of cellular proliferation and survival. The cell growth and survival regulating RAS/MAPK pathway remained unaffected. Knockdown in the HER2-positive cell line SKBR3 led to increased Met phosphorylation and decreased RAS/MAPK-related Erk phosphorylation as well as EGF-mediated transcription factor STAT3 phosphorylation. These results indicate that the role of PTPN2 in breast cancer is subtype-related and needs to be further investigated for future treatment options.

    List of papers
    1. Met and its ligand HGF are associated with clinical outcome in breast cancer
    Open this publication in new window or tab >>Met and its ligand HGF are associated with clinical outcome in breast cancer
    Show others...
    2016 (English)In: OncoTarget, ISSN 1949-2553, E-ISSN 1949-2553, Vol. 7, no 24, 37145-37159 p.Article in journal (Refereed) Published
    Abstract [en]

    Few biomarkers exist to predict radiotherapy response in breast cancer. In vitro studies suggest a role for Met and its ligand HGF. To study this suggested role, MET and HGF gene copy numbers were determined by droplet digital PCR in tumours from 205 pre-menopausal and 184 post-menopausal patients, both cohorts randomised to receive either chemo-or radiotherapy. MET amplification was found in 8% of the patients in both cohorts and HGF amplification in 7% and 6% of the patients in the pre-and post-menopausal cohort, respectively. Met, phosphorylated Met (pMet), and HGF protein expression was determined by immunohistochemistry in the premenopausal cohort. Met, pMet, and HGF was expressed in 33%, 53%, and 49% of the tumours, respectively. MET amplification was associated with increased risk of distant recurrence for patients receiving chemotherapy. For the pre-menopausal patients, expression of cytoplasmic pMet and HGF significantly predicted benefit from radiotherapy in terms of loco-regional recurrence. Similar trends were seen for MET and HGF copy gain. In the post-menopausal cohort, no significant association of benefit from radiotherapy with neither genes nor proteins was found. The present results do not support that inhibition of Met prior to radiotherapy would be favourable for pre-menopausal breast cancer, as previously suggested.

    Place, publisher, year, edition, pages
    IMPACT JOURNALS LLC, 2016
    Keyword
    radiation; copy number variation; droplet digital PCR; triple-negative breast cancer; radiotherapy
    National Category
    Cancer and Oncology
    Identifiers
    urn:nbn:se:liu:diva-130130 (URN)10.18632/oncotarget.9268 (DOI)000377756800127 ()27175600 (PubMedID)
    Note

    Funding Agencies|Swedish Cancer Society; Swedish Research Council; LiU Cancer Foundation

    Available from: 2016-07-12 Created: 2016-07-11 Last updated: 2017-03-07
  • Public defence: 2017-04-21 09:15 TP1, Täppan, Norrköping
    Žitinski Elías, Paula
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Improving image quality in multi-channel printing - multilevel halftoning, color separation and graininess characterization2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Color printing is traditionally achieved by separating an input image into four channels (CMYK) and binarizing them using halftoning algorithms, in order to designate the locations of ink droplet placement. Multi-channel printing means a reproduction that employs additional inks other than these four in order to augment the color gamut (scope of reproducible colors) and reduce undesirable ink droplet visibility, so-called graininess.

    One aim of this dissertation has been to characterize a print setup in which both the primary inks CMYK and their light versions are used. The presented approach groups the inks, forming subsets, each representing a channel that is reproduced with multiple inks. To halftone the separated channels in the present methodology, a specific multilevel halftoning algorithm is employed, halftoning each channel to multiple levels. This algorithm performs the binarization from the ink subsets to each separate colorant. Consequently, the print characterization complexity remains unaltered when employing the light inks, avoiding the normal increase in computational complexity, the one-to-many mapping problem and the increase in the number of training samples. The results show that the reproduction is visually improved in terms of graininess and detail enhancement.

    The secondary color inks RGB are added in multi-channel printing to increase the color gamut. Utilizing them, however, potentially increases the perceived graininess. Moreover, employing the primary, secondary and light inks means a color separation from a three-channel CIELAB space into a multi-channel colorant space, resulting in colorimetric redundancy in which multiple ink combinations can reproduce the same target color. To address this, a proposed cost function is incorporated in the color separation approach, weighting selected factors that influence the reproduced image quality, i.e. graininess and color accuracy, in order to select the optimal ink combination. The perceived graininess is modeled by employing S-CIELAB, a spatial low-pass filtering mimicking the human visual system. By applying the filtering to a large dataset, a generalized prediction that quantifies the perceived graininess is carried out and incorporated as a criterion in the color separation.

    Consequently, the presented research increases the understanding of color reproduction and image quality in multi-channel printing, provides concrete solutions to challenges in the practical implementation, and rises the possibilities to fully utilize the potential in multi-channel printing for superior image quality.

  • Public defence: 2017-04-21 10:00 Sal I:101, Hus I, Linköping
    Silfvernagel, Kristin
    Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
    Individually tailored internet-based cognitive behavioural therapy for adolescents, young adults and older adults with anxiety2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anxiety disorders share the feature of excessive fear, anxiety and related behavioural disturbances. Fear is defined as the emotional response to a real or a perceived imminent threat and anxiety is the anticipation of a future threat. The anxiety disorders covered in this thesis are panic disorder with or without agoraphobia, social phobia, post-traumatic stress disorder, generalized anxiety disorder and anxiety disorder not otherwise specified.

    Cognitive behavioural treatment protocols are typically designed to target one specific disorder and falls under the definition of disorder-specific cognitive behavioural therapy. It is however unclear if this is the most optimal approach in regards to the high comorbidity between anxiety disorders and depressive disorders. Internet-based cognitive behavioural therapy has in the past generally been disorder-specific and from above mentioned predicament two alternative treatment approaches emerged, the tailored and the transdiagnostic approach that aims to simultaneously treat both principal and comorbid disorders. Previous trials on internet-based cognitive behavioural therapy have targeted adults in general and relatively few target adolescents, young adults and older adults.

    The aims of this thesis were to further develop and test the effects of tailored internet-based cognitive behavioural therapy on the basis of age, for adolescents, young adults and older adults. Specifically by developing and testing the effects of individually tailored internet-based cognitive behavioural therapy for adolescents with anxiety and comorbid depressive symptoms and by adapting and testing the effects of individually tailored internet-based cognitive behavioural therapy for young adults and older adults with anxiety and comorbid depressive symptoms. These aims were tested in two pilot effectiveness studies (Paper I and III) and two efficacy randomised controlled trials (Paper II and IV). The results from these four trials showed significant results across all outcome measures with overall moderate to large effect sizes. The tentative conclusion based on these results is that tailoring internet-based cognitive behavioural therapy can be a feasible approach in the treatment of anxiety symptoms and comorbid depressive symptoms for adolescents, young adults and older adults. Despite the positive findings of the studies in this thesis, there is a need for more research examining the acceptability and effectiveness of internet-based cognitive behavioural therapy for adolescents, young adults and older adults with anxiety and depression before implementation on a larger scale.

    List of papers
    1. Individually Tailored Internet-Based Treatment for Young Adults and Adults With Panic Attacks: Randomized Controlled Trial
    Open this publication in new window or tab >>Individually Tailored Internet-Based Treatment for Young Adults and Adults With Panic Attacks: Randomized Controlled Trial
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    2012 (English)In: Journal of Medical Internet Research, ISSN 1438-8871, Vol. 14, no 3, 32-44 p.Article in journal (Refereed) Published
    Abstract [en]

    Background: Previous studies on Internet-based treatment with minimal therapist guidance have shown promising results for several specific diagnoses. Objective: To 91) investigate the effects of a tailored, therapist-guided, Internet-based treatment for individuals with reoccurring panic attacks, and 92) to examine whether people in different age groups 918-30 years and 31-45 years) would respond differently to the treatment. Methods: We recruited 149 participants from an online list of individuals having expressed an interest in Internet treatment. Screening consisted of online questionnaires followed by a telephone interview. A total of 57 participants were included after a semistructured diagnostic interview, and they were randomly assigned to an 8-week treatment program 9n = 29) or to a control condition 9n = 28). Treatment consisted of individually prescribed cognitive behavior therapy text modules in conjunction with online therapist guidance. The control group consisted of people on a waitlist who later received treatment. Results: All dependent measures improved significantly immediately following treatment and at the 12-month follow-up. The between-group effect size on the primary outcome measure, the Panic Disorder Severity Scale, was d = 1.41 995% confidence interval 0.81-1.95) at posttreatment. The within-group effect size from pretreatment to 12-month follow-up was d = 1.66 995% confidence interval 1.14-2.35). Age group had no effect, suggesting that age did not influence the outcome. Conclusions: Tailoring an Internet-based treatment can be a feasible approach in the treatment of panic symptoms and comorbid anxiety and depressive symptoms. Younger adults benefit as much as adults over 30 years and up to 45 years of age.

    Place, publisher, year, edition, pages
    Journal of Medical Internet Research, 2012
    Keyword
    Anxiety; depression; effectiveness; Internet-based treatment; cognitive behavior therapy
    National Category
    Social Sciences
    Identifiers
    urn:nbn:se:liu:diva-79782 (URN)10.2196/jmir.1853 (DOI)000305797300003 ()
    Available from: 2012-08-17 Created: 2012-08-14 Last updated: 2017-03-23
    2. Individually tailored internet-based cognitive behavior therapy for adolescents with anxiety disorders: A pilot effectiveness study
    Open this publication in new window or tab >>Individually tailored internet-based cognitive behavior therapy for adolescents with anxiety disorders: A pilot effectiveness study
    Show others...
    2015 (English)In: Internet Interventions, ISSN 2214-7829, Vol. 2, no 3, 297-302 p.Article in journal (Refereed) Published
    Abstract [en]

    This is the first study of adolescents suffering from anxiety disorder in Sweden to receive individually tailored internet-based treatment within a child and adolescent psychiatric clinic. The primary aim of this effectiveness study was to examine the effects of tailored internet-based cognitive behaviour therapy for adolescents.

    11 adolescents, aged 15-19 years, were allocated to treatment after assessment. Screening consisted of online questionnaires followed by a diagnostic face-to-face interview at the clinic. Treatment consisted of individually prescribed cognitive behaviour therapy (CBT) text modules adapted for the age group. Therapist guidance was via an online platform along with telephone support and face-to-face sessions if needed.

    Statistically significant improvements were found on all dependent measures immediately following treatment for the 8 adolescents who completed treatment. The within-group effect size on the Beck Anxiety Inventory, the primary outcome measure, was d = 2.51 at post-treatment and 80 percent (4/5) adolescents no longer met DSM-IV criteria for their primary anxiety disorder as measured by the Anxiety Disorders Interview Schedule for DSM- IV: Child and Parent Versions.

    Based on the results from this pilot study the tentative conclusion might be that tailored internet delivered CBT could be useful for adolescents with anxiety disorders along with standard treatment delivered in child and adolescent psychiatric clinics.

    Keyword
    Adolescent;Anxiety disorders;Cognitive behavior therapy;Internet-based treatment
    National Category
    Psychiatry
    Identifiers
    urn:nbn:se:liu:diva-125381 (URN)10.1016/j.invent.2015.07.002 (DOI)
    Available from: 2016-02-22 Created: 2016-02-22 Last updated: 2017-03-23
  • Public defence: 2017-04-21 10:15 Visionen, B-huset, Linköping
    Roth, Michael
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Advanced Kalman Filtering Approaches to Bayesian State Estimation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bayesian state estimation is a flexible framework to address relevant problems at the heart of existing and upcoming technologies. Application examples are obstacle tracking for driverless cars and indoor navigation using smartphone sensor data. Unfortunately, the mathematical solutions of the underlying theory cannot be translated to computer code in general. Therefore, this thesis discusses algorithms and approximations that are related to the Kalman filter (KF).

    Four scientific articles and an introduction with the relevant background on Bayesian state estimation theory and algorithms are included. Two articles discuss nonlinear Kalman filters, which employ the KF measurement update in nonlinear models. The numerous variants are presented in a common framework and the employed moment approximations are analyzed. Furthermore, their application to target tracking problems is discussed. A third article analyzes the ensemble Kalman filter (EnKF), a Monte Carlo implementation of the KF that has been developed for high-dimensional geoscientific filtering problems. The EnKF is presented in a simple KF framework, including its challenges, important extensions, and relations to other filters. Whereas the aforementioned articles contribute to the understanding of existing algorithms, a fourth article devises novel filters and smoothers to address heavy-tailed noise. The development is based on Student’s t distribution and provides simple recursions in the spirit of the KF. The introduction and articles are accompanied by extensive simulation experiments.

    List of papers
    1. Nonlinear Kalman Filters Explained: A Tutorial on Moment Computations and Sigma Point Methods
    Open this publication in new window or tab >>Nonlinear Kalman Filters Explained: A Tutorial on Moment Computations and Sigma Point Methods
    2016 (English)In: Journal of Advances in Information Fusion, ISSN 1557-6418, Vol. 11, no 1, 47-70 p.Article in journal (Refereed) Published
    Abstract [en]

    Nonlinear Kalman filters are algorithms that approximately solve the Bayesian filtering problem by employing the measurement update of the linear Kalman filter (KF). Numerous variants have been developed over the past decades, perhaps most importantly the popular sampling based sigma point Kalman filters.In order to make the vast literature accessible, we present nonlinear KF variants in a common framework that highlights the computation of mean values and covariance matrices as the main challenge. The way in which these moment integrals are approximated distinguishes, for example, the unscented KF from the divided difference KF.With the KF framework in mind, a moment computation problem is defined and analyzed. It is shown how structural properties can be exploited to simplify its solution. Established moment computation methods, and their basics and extensions, are discussed in an extensive survey. The focus is on the sampling based rules that are used in sigma point KF. More specifically, we present three categories of methods that use sigma-points 1) to represent a distribution (as in the UKF); 2) for numerical integration (as in Gauss-Hermite quadrature); 3) to approximate nonlinear functions (as in interpolation). Prospective benefits and downsides are listed for each of the categories and methods, including accuracy statements. Furthermore, the related KF publications are listed.The theoretical discussion is complemented with a comparative simulation study on instructive examples.

    Place, publisher, year, edition, pages
    International society of information fusion, 2016
    National Category
    Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-129231 (URN)
    Available from: 2016-06-14 Created: 2016-06-14 Last updated: 2017-02-27Bibliographically approved
    2. EKF/UKF Maneuvering Target Tracking using Coordinated Turn Models with Polar/Cartesian Velocity
    Open this publication in new window or tab >>EKF/UKF Maneuvering Target Tracking using Coordinated Turn Models with Polar/Cartesian Velocity
    2014 (English)In: 17th International Conference on Information Fusion (FUSION), 2014, Institute of Electrical and Electronics Engineers (IEEE), 2014, 1-8 p.Conference paper (Refereed)
    Abstract [en]

    Nonlinear Kalman filter adaptations such as extended Kalman filters (EKF) or unscented Kalman filters (UKF) provide approximate solutions to state estimation problems in nonlinear models. The algorithms utilize mean values and covariance matrices to represent the probability densities in the otherwise intractable Bayesian filtering equations. As a consequence, their estimation performance can show significant dependence on the choice of state coordinates. The here considered problem of tracking maneuvering targets using coordinated turn (CT) models is one practically relevant example: The velocity in the target state can either be formulated in Cartesian or polar coordinates. We extend a previous study to a broader range of CT models that allow for changes in target speed and turn rate, and investigate UKF as well as EKF variants in terms of their performance and sensitivity to noise parameters. The results advocate for the use of polar CT models.

    Place, publisher, year, edition, pages
    Institute of Electrical and Electronics Engineers (IEEE), 2014
    Keyword
    Coordinated turn model; Maneuvering target tracking
    National Category
    Control Engineering Signal Processing
    Identifiers
    urn:nbn:se:liu:diva-108957 (URN)000363896100153 ()978-849012355-3 (ISBN)
    Conference
    17th International Conference on Information Fusion, Salamanca, Spain, July 7-10, 2014
    Funder
    Security LinkSwedish Foundation for Strategic Research
    Available from: 2014-07-14 Created: 2014-07-14 Last updated: 2017-02-27
  • Public defence: 2017-04-25 10:15 K3, Kåkenhus, Norrköping
    Volkov, Anton
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ionic and electronic transport in electrochemical and polymer based systems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrochemical systems, which rely on coupled phenomena of the chemical change and electricity, have been utilized for development an interface between biological systems and conventional electronics.  The development and detailed understanding of the operation mechanism of such interfaces have a great importance to many fields within life science and conventional electronics. Conducting polymer materials are extensively used as a building block in various applications due to their ability to transduce chemical signal to electrical one and vice versa. The mechanism of the coupling between the mass and charge transfer in electrochemical systems, and particularly in conductive polymer based system, is highly complex and depends on various physical and chemical properties of the materials composing the system of interest.

    The aims of this thesis have been to study electrochemical systems including conductive polymer based systems and provide knowledge for future development of the devices, which can operate with both chemical and electrical signals. Within the thesis, we studied the operation mechanism of ion bipolar junction transistor (IBJT), which have been previously utilized to modulate delivery of charged molecules. We analysed the different operation modes of IBJT and transition between them on the basis of detailed concentration and potential profiles provided by the model.

    We also performed investigation of capacitive charging in conductive PEDOT:PSS polymer electrode. We demonstrated that capacitive charging of PEDOT:PSS electrode at the cyclic voltammetry, can be understood within a modified Nernst-Planck-Poisson formalism for two phase system in terms of the coupled ion-electron diffusion and migration without invoking the assumption of any redox reactions.

    Further, we studied electronic structure and optical properties of a self-doped p-type conducting polymer, which can polymerize itself along the stem of the plants. We performed ab initio calculations for this system in undoped, polaron and bipolaron electronic states. Comparison with experimental data confirmed the formation of undoped or bipolaron states in polymer film depending on applied biases.

    Finally, we performed simulation of the reduction-oxidation reaction at microband array electrodes. We showed that faradaic current density at microband array electrodes increases due to non-linear mass transport on the microscale compared to the corresponding macroscale systems.  The studied microband array electrode was used for developing a laccase-based microband biosensor. The biosensor revealed improved analytical performance, and was utilized for in situ phenol detection.

    List of papers
    1. Modeling of Charge Transport in Ion Bipolar Junction Transistors
    Open this publication in new window or tab >>Modeling of Charge Transport in Ion Bipolar Junction Transistors
    2014 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 23, 6999-7005 p.Article in journal (Refereed) Published
    Abstract [en]

    Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poissons and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2014
    National Category
    Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-109131 (URN)10.1021/la404296g (DOI)000337644200044 ()24854432 (PubMedID)
    Available from: 2014-08-13 Created: 2014-08-11 Last updated: 2017-03-17Bibliographically approved
    2. In vivo polymerization and manufacturing of wires and supercapacitors in plants
    Open this publication in new window or tab >>In vivo polymerization and manufacturing of wires and supercapacitors in plants
    Show others...
    2017 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 11, 2807-2812 p.Article in journal (Refereed) Published
    Abstract [en]

    Electronic plants, e-Plants, are an organic bioelectronic platform that allows electronic interfacing with plants. Recently we have demonstrated plants with augmented electronic functionality. Using the vascular system and organs of a plant, we manufactured organic electronic devices and circuits in vivo, leveraging the internal structure and physiology of the plant as the template, and an integral part of the devices. However, this electronic functionality was only achieved in localized regions, whereas new electronic materials that could be distributed to every part of the plant would provide versatility in device and circuit fabrication and create possibilities for new device concepts. Here we report the synthesis of such a conjugated oligomer that can be distributed and form longer oligomers and polymer in every part of the xylem vascular tissue of a Rosa floribunda cutting, forming long-range conducting wires. The plant’s structure acts as a physical template, whereas the plant’s biochemical response mechanism acts as the catalyst for polymerization. In addition, the oligomer can cross through the veins and enter the apoplastic space in the leaves. Finally, using the plant’s natural architecture we manufacture supercapacitors along the stem. Our results are preludes to autonomous energy systems integrated within plants and distribute interconnected sensor-actuator systems for plant control and optimization

    Place, publisher, year, edition, pages
    National Academy of Sciences, 2017
    National Category
    Plant Biotechnology Condensed Matter Physics Textile, Rubber and Polymeric Materials Chemical Sciences
    Identifiers
    urn:nbn:se:liu:diva-135492 (URN)10.1073/pnas.1616456114 (DOI)
    Available from: 2017-03-16 Created: 2017-03-16 Last updated: 2017-03-27Bibliographically approved
    3. Total phenol analysis of weakly supported water using a laccase-based microband biosensor.
    Open this publication in new window or tab >>Total phenol analysis of weakly supported water using a laccase-based microband biosensor.
    Show others...
    2016 (English)In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 907, 45-53 p.Article in journal (Refereed) Published
    Abstract [en]

    The monitoring of phenolic compounds in wastewaters in a simple manner is of great importance for environmental control. Here, a novel screen printed laccase-based microband array for in situ, total phenol estimation in wastewaters and for water quality monitoring without additional sample pre-treatment is presented. Numerical simulations using the finite element method were utilized for the characterization of micro-scale graphite electrodes. Anodization followed by covalent modification was used for the electrode functionalization with laccase. The functionalization efficiency and the electrochemical performance in direct and catechol-mediated oxygen reduction were studied at the microband laccase electrodes and compared with macro-scale electrode structures. The reduction of the dimensions of the enzyme biosensor, when used under optimized conditions, led to a significant improvement in its analytical characteristics. The elaborated microsensor showed fast responses towards catechol additions to tap water – a weakly supported medium – characterized by a linear range from 0.2 to 10 μM, a sensitivity of 1.35 ± 0.4 A M−1 cm−2 and a dynamic range up to 43 μM. This enhanced laccase-based microsensor was used for water quality monitoring and its performance for total phenol analysis of wastewater samples from different stages of the cleaning process was compared to a standard method.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    Keyword
    Laccase; microelectrode; microband; electrochemical modeling; total phenol analysis; wastewater
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-123677 (URN)10.1016/j.aca.2015.12.006 (DOI)000368422900005 ()
    Note

    Funding agencies: Swedish research council Formas [245-2010-1062]; research centre Security Link [VINNOVA 2009-00966]; Norrkopings fond for Forskning och Utveckling; VINNOVA

    Available from: 2016-01-07 Created: 2016-01-07 Last updated: 2017-03-17Bibliographically approved
  • Public defence: 2017-04-28 13:15 Visionen, B-huset, Linköping
    Orlof, Anna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Quantumscattering and interaction in graphene structures2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since its isolation in 2004, that resulted in the Nobel Prize award in 2010, graphene has been the object of an intense interest, due to its novel physics and possible applications in electronic devices. Graphene has many properties that differ it from usual semiconductors, for example its low-energy electrons behave like massless particles. To exploit the full potential of this material, one first needs to investigate its fundamental properties that depend on shape, number of layers, defects and interaction. The goal of this thesis is to perform such an investigation.

    In paper I, we study electronic transport in monolayer and bilayer graphene nanoribbons with single and many short-range defects, focusing on the role of the edge termination (zigzag vs armchair). Within the discrete tight-binding model, we perform an-alytical analysis of the scattering on a single defect and combine it with the numerical calculations based on the Recursive Green's Function technique for many defects. We find that conductivity of zigzag nanoribbons is practically insensitive to defects situated close to the edges. In contrast, armchair nanoribbons are strongly affected by such defects, even in small concentration. When the concentration of the defects increases, the difference between different edge terminations disappears. This behaviour is related to the effective boundary condition at the edges, which respectively does not and does couple valleys for zigzag and armchair ribbons. We also study the Fano resonances.

    In the second paper we consider electron-electron interaction in graphene quantum dots defined by external electrostatic potential and a high magnetic field. The interaction is introduced on the semi-classical level within the Thomas Fermi approximation and results in compressible strips, visible in the potential profile. We numerically solve the Dirac equation for our quantum dot and demonstrate that compressible strips lead to the appearance of plateaus in the electron energies as a function of the magnetic field. This analysis is complemented by the last paper (VI) covering a general error estimation of eigenvalues for unbounded linear operators, which can be used for the energy spectrum of the quantum dot considered in paper II. We show that an error estimate for the approximate eigenvalues can be obtained by evaluating the residual for an approximate eigenpair. The interpolation scheme is selected in such a way that the residual can be evaluated analytically.

    In the papers III, IV and V, we focus on the scattering on ultra-low long-range potentials in graphene nanoribbons. Within the continuous Dirac model, we perform analytical analysis and show that, considering scattering of not only the propagating modes but also a few extended modes, we can predict the appearance of the trapped mode with an energy eigenvalue close to one of the thresholds in the continuous spectrum. We prove that trapped modes do not appear outside the threshold, provided the potential is sufficiently small. The approach to the problem is different for zigzag vs armchair nanoribbons as the related systems are non-elliptic and elliptic respectively; however the resulting condition for the existence of the trapped mode is analogous in both cases.

    List of papers
    1. Effect of zigzag and armchair edges on the electronic transport in single-layer and bilayer graphene nanoribbons with defects
    Open this publication in new window or tab >>Effect of zigzag and armchair edges on the electronic transport in single-layer and bilayer graphene nanoribbons with defects
    2013 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, no 12Article in journal (Refereed) Published
    Abstract [en]

    We study electronic transport in monolayer and bilayer graphene with single and many short-range defects focusing on the role of edge termination (zigzag versus armchair). Within the tight-binding approximation, we derive analytical expressions for the transmission amplitude in monolayer graphene nanoribbons with a single short-range defect. The analytical calculations are complemented by exact numerical transport calculations for monolayer and bilayer graphene nanoribbons with a single and many short-range defects and edge disorder. We find that for the case of the zigzag edge termination, both monolayer and bilayer nanoribbons in a single- and few-mode regime remain practically insensitive to defects situated close to the edges. In contrast, the transmission of both armchair monolayer and bilayer nanoribbons is strongly affected by even a small edge defect concentration. This behavior is related to the effective boundary condition at the edges, which, respectively, does not and does couple valleys for zigzag and armchair nanoribbons. In the many-mode regime and for sufficiently high defect concentration, the difference of the transmission between armchair and zigzag nanoribbons diminishes. We also study resonant features (Fano resonances) in monolayer and bilayer nanoribbons in a single-mode regime with a short-range defect. We discuss in detail how an interplay between the defect's position at different sublattices in the ribbons, the defect's distance to the edge, and the structure of the extended states in ribbons with different edge termination influence the width and the energy of Fano resonances.

    Place, publisher, year, edition, pages
    American Physical Society, 2013
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-98145 (URN)10.1103/PhysRevB.88.125409 (DOI)000323944800009 ()
    Note

    Funding Agencies|Swedish Institute||

    Available from: 2013-09-30 Created: 2013-09-30 Last updated: 2017-03-27
    2. Electron-electron interactions in graphene field-induced quantum dots in a high magnetic field
    Open this publication in new window or tab >>Electron-electron interactions in graphene field-induced quantum dots in a high magnetic field
    2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 7, 075431- p.Article in journal (Refereed) Published
    Abstract [en]

    We study the effect of electron-electron interaction in graphene quantum dots defined by an external electrostatic potential and a high magnetic field. To account for the electron-electron interaction, we use the Thomas-Fermi approximation and find that electron screening causes the formation of compressible strips in the potential profile and the electron density. We numerically solve the Dirac equations describing the electron dynamics in quantum dots, and we demonstrate that compressible strips lead to the appearance of plateaus in the electron energies as a function of the magnetic field. Finally, we discuss how our predictions can be observed using the Kelvin probe force microscope measurements.

    Place, publisher, year, edition, pages
    American Physical Society, 2015
    National Category
    Mathematics Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-121107 (URN)10.1103/PhysRevB.92.075431 (DOI)000359859900004 ()
    Note

    Funding Agencies|Danish National Research Foundation [DNRF58]

    Available from: 2015-09-07 Created: 2015-09-07 Last updated: 2017-03-27
    3. Trapped modes supported by localized potentials in the zigzag graphene ribbon
    Open this publication in new window or tab >>Trapped modes supported by localized potentials in the zigzag graphene ribbon
    2016 (English)In: Comptes rendus. Mathematique, ISSN 1631-073X, E-ISSN 1778-3569, Vol. 354, no 1, 63-67 p.Article in journal (Refereed) Published
    Abstract [en]

    Localized potentials in the Dirac equation for the electron dynamics in a zigzag graphene ribbon are constructed to support trapped modes while the corresponding eigenvalues are embedded into the continuous spectrum. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

    Place, publisher, year, edition, pages
    ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2016
    National Category
    Mathematics
    Identifiers
    urn:nbn:se:liu:diva-127590 (URN)10.1016/j.crrna.2015.10.007 (DOI)000373518100011 ()
    Note

    Funding Agencies|Linkoping University; Russian Foundation of Basic Research [15-01-02175]

    Available from: 2016-05-03 Created: 2016-05-03 Last updated: 2017-03-27
    4. Error Estimation for Eigenvalues of Unbounded Linear Operators and an Application to Energy Levels in Graphene Quantum Dots
    Open this publication in new window or tab >>Error Estimation for Eigenvalues of Unbounded Linear Operators and an Application to Energy Levels in Graphene Quantum Dots
    2017 (English)In: Numerical Functional Analysis and Optimization, ISSN 0163-0563, E-ISSN 1532-2467, Vol. 38, no 3, 293-305 p.Article in journal (Refereed) Published
    Abstract [en]

    The eigenvalue problem for linear differential operators is important since eigenvalues correspond to the possible energy levels of a physical system. It is also important to have good estimates of the error in the computed eigenvalues. In this work, we use spline interpolation to construct approximate eigenfunctions of a linear operator using the corresponding eigenvectors of a discretized approximation of the operator. We show that an error estimate for the approximate eigenvalues can be obtained by evaluating the residual for an approximate eigenpair. The interpolation scheme is selected in such a way that the residual can be evaluated analytically. To demonstrate that the method gives useful error bounds, we apply it to a problem originating from the study of graphene quantum dots where the goal was to investigate the change in the spectrum from incorporating electron–electron interactions in the potential.

    Keyword
    Energy levels, error estimation, graphene, linear operator, quantum dot, spectrum
    National Category
    Computational Mathematics Mathematical Analysis
    Identifiers
    urn:nbn:se:liu:diva-135540 (URN)10.1080/01630563.2017.1279176 (DOI)
    Available from: 2017-03-22 Created: 2017-03-22 Last updated: 2017-03-27
  • 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: 2017-03-27Bibliographically approved
    3. Self-reinforcing Mechanisms in a Multi-technology Industry: Understanding Sustained Technological Variety in a Context of Path Dependency
    Open this publication in new window or tab >>Self-reinforcing Mechanisms in a Multi-technology Industry: Understanding Sustained Technological Variety in a Context of Path Dependency
    2015 (English)In: Industry and Innovation, ISSN 1366-2716, E-ISSN 1469-8390, Vol. 22, no 6, 523-551 p.Article in journal (Refereed) Published
    Abstract [en]

    This paper studies self-reinforcing mechanisms in multi-technology industries, i.e. industries in which technological lock-in does not occur and several technologies continue to coexist. The purpose of this paper is to investigate what kind of self-reinforcing mechanisms can be present in such industries and explain how multiple paths can coexist and interact in a context of self-reinforcement and, ultimately, path dependency. Building on the empirical example of the lighting industry, the paper shows that all previously recognized types of self-reinforcing mechanisms can be present in a multi-technology industry. However, in addition to the path-internal positive feedbacks and cross-path negative externalities identified in single-path settings, multi-technology industries also experience positive cross-path externalities that create a symbiotic relationship between alternatives and allow for the reproduction of the same development pattern across technologies. Due to the existence of such non-negative technology interactions, multi-technology industries can be path dependent while still retaining technological variety.

    Place, publisher, year, edition, pages
    ROUTLEDGE JOURNALS, TAYLOR and FRANCIS LTD, 2015
    Keyword
    Self-reinforcing mechanisms; path dependency; multi-technology industries; lighting industry
    National Category
    Economics and Business
    Identifiers
    urn:nbn:se:liu:diva-123163 (URN)10.1080/13662716.2015.1100532 (DOI)000364722200004 ()
    Note

    Funding Agencies|Riksbankens Jubileumsfond via the KITE research program [M2006-0231]

    Available from: 2015-12-06 Created: 2015-12-04 Last updated: 2017-03-27