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  • Public defence: 2018-10-25 09:15 M102, Sundsvall
    Mattsson, Amanda
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Characterisation of Time-dependent Statistical Failure of Fibre Networks: Applications for Light-weight Structural Composites2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The future of a sustainable society requires that materials not only be renewable, but also leave as small a carbon foot-printin the environment as possible. One such product is light-weight composite material for transportation packages. Cellulose fibres have been and will continue to be ideal for this purpose.

    The strength design of light-weight composites is becoming increasingly important. The challenge is to neither over- nor under-design, but instead to target the right strength underrealistic loading conditions. The question then is: What is right strength? Under realistic loading conditions (e.g., fatigue, random loading, and creep), materials fail differently from what one expects from tests of static strength: materials often fail at much lower stresses than are measured in these tests, the failure is time-dependent, and time to failure is highly variable. Therefore, to answer the above question, we have set up the following objectives: (1) theoretically formulate time-dependent statistical failure (TSF), and examine the validity of the model; (2) define material parameters describing the multi-faceted strength characteristics based on this formulation; (3) develop an experimental method to determine the material parameters; (4) investigate the impacts of fibre properties and network structures; and finally (5) characterise containerboard (the fibre material used in corrugated boxes) samples in terms of the new material parameters. The results for these five objectives are presented below, one by one.

    (1) A general formulation of TSF, originally proposed byColeman [1] for fibre failures, has been used. We have found that this model is indeed valid, even at the fibre network level, with only two restrictions: the existence of a lower bound onweakest-link scaling and an approximate nature of the Weibull distribution.

    (2) Accordingly, we have defined three material parameters that characterise different aspects of material strength: shortterm strength, durability/brittleness, and reliability. We call these parameters the new strength metrics.

    (3) Although the newly defined material parameters are most comprehensive, it takes up to several months to determine them by using creep tests. We have developed a new method, using constant loading rate (CLR) tests, that not only gives values comparable to those from creep tests, but also requires only about one day, allowing a drastic reduction in the testing time.

    (4) Monte-Carlo simulations of lattice networks have been performed to determine the basic relationships between fibre properties and network failures. The brittleness of an individual fibre (or a breaking element) influenced both brittleness and reliability of the fibre network, the higher the brittleness, the lower the reliability. Reliability, on the other hand, exhibited more intricate relationships with fibre properties and network structures. Several important analytical relationships have been derived.

    (5) Finally, using the CLR tests, we have characterised commercial containerboards in terms of the new strength metrics. Containerboard, as a cellulose fibre network, is quite comparable to typical stiff polymer-based fibre composites (e.g., glassfibres and aramid fibres). However, the reliability and durability/brittlenessof containerboard varied considerably within the operating windows, suggesting ample opportunities to fine-tune these properties even using current papermaking practices.The fact that the multi-faceted nature of strength can be expressed by three parameters is remarkable, and the implications are profound for how materials are designed and new materials developed. It is the author’s hope that this thesis will be of some use when it comes to redefining materials for a sustainable society, particularly the renewable alternative –cellulose fibres.

  • Public defence: 2018-10-26 10:00 F234, Östersund
    Rondung, Elisabet
    Mid Sweden University, Faculty of Human Sciences, Department of Psychology.
    Psychological perspectives on fear of birth: heterogeneity, mechanisms and treatment2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Although it is medically safe to give birth in most western countries, the vast majority of pregnant women experience some kind of anxiety, fear or worry in relation to their pregnancy or the upcoming childbirth. Most pregnant women find ways of coping with these issues but, for many, fear of birth is a significant source of distress during pregnancy, with negative consequences both when giving birth and in the postpartum period.

    Previous research on fear of birth has for the most part had a medical perspective, investigating risk factors and consequences of this form of fear or anxiety, along with studies evaluating different forms of interventions. The general aim of this thesis was to approach fear of birth from a psychological perspective, by exploring the role of psychological factors in this form of fear, worry or anxiety.

    Four studies are included in the thesis. The first study is a randomized controlled trial, in which we compared a guided Internet-delivered self-help program, based on cognitive behavior therapy (guided ICBT), with standard care (midwife led fear of birth specific counseling), for the treatment of fear of birth. Despite poor adherence to the guided ICBT, the results showed a similar reduction in fear levels during pregnancy in both groups, with lower levels of fear of birth in the guided ICBT group one year after birth. The second study is a narrative literature review. This study adopted a psychological perspective on the existing literature describing fear of birth, with a special focus on the specificity of this form of fear or anxiety, the pathways of fear acquisition, and the physiological, cognitive and behavioral aspects of fear of birth. Using systematic procedures for the literature search, inclusion and exclusion, 89 original research papers were included and summarized in the study. The aim of the third study was to explore possible heterogeneity among pregnant women reporting high levels of fear of birth. Comparisons between primiparous and multiparous women revealed that these groups were very similar in their levels of fear of birth as well as in the psychological variables investigated. Using a series of hierarchical and non-hierarchical cluster analyses, five possible subgroups based on psychological characteristics were identified, pointing to psychological heterogeneity among women fearing birth. In the fourth study, our aim was to take a first step in trying to identify psychological mechanisms relevant to the understanding of fear of birth. In this study, pain catastrophizing and intolerance of uncertainty were clear predictors of fear of birth, while parity was not.

    Taken together, the results of the four studies included in this thesis indicate that fear of birth is a concept in need of further investigation, and that psychological perspectives could offer an important contribution to our understanding of this form of fear or anxiety. Women fearing birth seem to be a heterogeneous group, and psychological characteristics (e.g. pain catastrophizing, or catastrophizing in general, and intolerance of uncertainty) might be of greater importance than parity in both describing this diversity and understanding the development and maintenance of fear of birth. Treating fear of birth using guided ICBT can be challenging, and before introducing this form of treatment as an alternative, further refinement and evaluation of the methods are needed.

  • Public defence: 2018-11-01 10:30 C326, Sundsvall
    Kleebthong, Duangkaew
    Mid Sweden University, Faculty of Human Sciences, Department of Nursing Sciences.
    Depression among older people in rural Thailand: Knowledge of population, experiences and perceptions of patients, families, and psychiatric nurses2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: The number of older persons (defined as age 60 and over) in Thailand has grown rapidly, and will be projected to increase to over 20 million by 2035. With an aging population, the number of older people suffering from health problems (such as non-communicable and degenerative diseases) was increasing as well. Older people faced physical and mental health challenges that need to be recognized. Depression among older people is significantly high and associated with physical illness; however it remains overlooked, improperly diagnosed, and inadequately treated.

    Aim: The overall aim of the study was to gain deeper knowledge of the phenomenon of depression in older people in rural Thai areas. The aim of each the study was to describe and understand the experiences and perceptions of individual psychiatric nurses, patients, and their family members, as well as to study public knowledge about depression among older people in rural Thailand.

    Methods: The setting of this thesis was a rural area in Thailand. It included four studies. The first three studies involved qualitative research, and latent content analysis was used to analyze data. In-depth interviews were used to collect data. Purposive sampling was used to select participants for the first three studies, which included 13 psychiatric nurses (study I), 14 older people with depression (study II), and 13 family members of older patients suffering from depression (study III). The fourth study is a quantitative cross-sectional study with 2,636 respondents aged 18 years to 75 and living in a household while data was collected. Respondents were selected using multi-stage random sampling.

    Results: Study I - The psychiatric nurses’ experiences and perceptions of their professional role were mirrored in the following themes: 1) managing a central role in patient care; 2) conflicting interests between the professional needs of caregiving and other requests; and 3) being compassionate beyond their official duties. Study II - the experiences and perceptions of older Thai people with depression were abstracted into two themes. The first theme was 1) leading a life of detachment, and the second theme was 2) inconvenience of obtaining mental health treatment. Study III - the experiences and perceptions of family members of older people showing major depression were abstracted into two themes. The first theme was 1) perceiving a traditional rural view on mental illness, and the second was 2) experiencing complexity in everyday life when caring for older depressed family member. Study IV - The 2,636 respondents have moderate knowledge about depression among older people, with a respondent mean score of 5.86 (SD = 1.68). Education level was significantly associated with knowledge about depression. If education level changes from lower to higher, the odds for level of knowledge about depression increase. This result may indicate the need for enhanced mental health literacy in rural areas.

    Conclusion: Older people with depression in a rural Thai area were the responsibility of an inadequate number of psychiatric nurses. The resultsshowed sign of lacking knowledge about depression among older people and an imbalance between the needs of patients and the mental health care provided by the psychiatric nurses in rural areas. The patients and their relatives, and psychiatric nurses felt burdened in daily life. An immediate concern for mental healthcare providers is providing mental literacy in rural areas. These primary results can be used by mental health authorities to develop plans to enhance quality of care for older people with depression, and as such, provide psychosocial support for patients and their family. This would reduce the burden on psychiatric nurses and adjust human resources in mental health services in district hospitals.

  • Public defence: 2018-12-05 10:00 F234, Östersund
    Champoux-Larsson, Marie-France
    Mid Sweden University, Faculty of Human Sciences, Department of Psychology.
    Perceiving emotions with a bilingual mind2018Doctoral thesis, comprehensive summary (Other academic)