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- Bergman, Niclas
(författare)
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Aspects of probabalistic serviceability limit state design of dry deep mixing
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An expanding population and increased need for infrastructure increasingly necessitate construction on surfaces with poor soil conditions. To facilitate the construction of buildings, roads and railroads in areas with poor soil conditions, these areas are often improved by means of foundation engineering. Constructions that are fairly limited in scope are often founded on shallow or deep foundations. However, these methods are relatively expensive and thus not applicable for large-scale constructions like roads and railroads. A cost-effective way to deal with poor soil conditions is to use ground improvement. This thesis deals with a ground improvement method called deep mixing (DD)using lime-cement columns.Lime-cement columns are manufactured by pushing a mechanical mixing tool to the desired depth, with the tool then rotated and retracted while a lime-cement binder is distributed into soil, forming lime-cement columns. Because of the complex mixing process and inherent soil variability, soil improved by DD shows high variability with respect to strength and deformation properties. Due to this high variability, it is difficult to predict the properties in advance; it is therefore important to verify the properties after installation. In Sweden, this is normally done using the column penetration test (KKK) method.Current design praxis considers evaluated mean values in the design, and the effect of variability and uncertainties is dealt with by using a sufficiently high total factor of safety. A more rational approach for dealing with the effect of variability and uncertainties on the reliability of a mechanical system is to include them as parameters in the design model. This can be done by using reliability-based design (RRR). A major incentive for using ??? is that lower variability in design properties produces higher design values. This is important since it encourages contractors to improve their manufacturing methodologies because ??? allows more homogenous columns to be assigned higher design values. Reliability-based design is also in line with Eurocode 7, which states that the selection of the characteristic values for geotechnical parameters shall take the variability of the measured property values into account.The first part of this doctoral thesis deals with test methods and quantification of the strength variability of soil improved by lime-cement columns. Tip resistances from three different test sites using three different penetration test methods – the cone penetration test, the column penetration test and the total-sounding test – are analysed and quantified in terms of means, variances and scale of fluctuations. The second part introduces RRR in serviceability limit state (SSS) design, using First Order Reliability Methods (FFFF) and Monte-Carlo simulations.Summarizing the most important findings and conclusions from this study: The scale of fluctuation was estimated to be 0.2-0.7 m and 0-3 m in the vertical and horizontal direction, respectively. The relation between cone tip resistances measured using the cone penetration test and column penetration test does not correspond to the cone factors proposed in previous studies and in the Swedish Design Guidelines. The agreement between the column penetration test and total-sounding test was found to be “good enough”. It is therefore suggested that the total-sounding test be used as a complement to the column penetration test in evaluating the average strength properties of a group of medium- and high-strength lime-cement columns.Reliability-based design is a rational approach to incorporate strength and deformation parameter variability with an SSS design.
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| 2. |
- Emilson, Christina, 1969-
(författare)
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Long-term perspectives on musculoskeletal pain : Health care utilization and integration of behavioral medicine treatment into physical therapy
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are currently no effective methods for treating and preventing chronic pain. The aim of this thesis was to study prognostic factors for health care utilization, and the long-term outcomes of tailored behavioral medicine treatment for patients with musculoskeletal pain. Another aim was to increase knowledge about physical therapists’ assessment and analysis of patients’ pain conditions and to investigate the potential of subgrouping patients based on prognostic factors.Methods: In Study I, a prospective population-based cohort was followed over 21 years. Data from three measure points were analyzed: 1995 (n=2425), 2007 (n=1582) and 2016 (n=1184). Study II was a 10-year follow-up of randomized controlled trial (n=97), comparing tailored behavioral medicine treatment and exercise-based physical therapy. In Study III, a descriptive and explorative design was applied, using data from video-recordings of 12 physical therapists. In study IV, assignment to three subgroups based on the Örebro Musculoskeletal Pain Screening Questionnaire was validated against reference instruments, and the stability between two points of measurement was investigated in patients (n=40) who were seeking primary health care due to musculoskeletal pain.Results: Chronic pain, female gender and high age predict high health care utilization over 21 years, and a trajectory of stable high health care utilization over the entire period. The differences between groups in favor for tailored behavioral medicine treatment reported at post-treatment and after two years, were not maintained at the 10-year follow-up. A majority of the physical therapists assessed factors for poor prognosis. The analyses were mainly based on biomedical assessments and none of the physical therapists included behavioral factors. Subgroup assignment according to the Örebro Musculoskeletal Pain Screening Questionnaire appears to be valid and stable over time.Conclusion: Prognostic factors such as chronic pain and female gender need to be considered when allocating health care resources and planning treatment to improve long-term outcomes. The treatment should also be tailored based on individual functional behavioral analyses of key behaviors and on patient´s biomedical and psychosocial condition, including strategies for maintenance of behavioral changes. Evidence-based methods for integrating behavioral medicine treatment into physical therapy need to be further evaluated and improved.
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| 3. |
- Lindholm, Annelie, 1975-
(författare)
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Overweight and Obesity in Preschool Children : Early Risk Factors and Early Identification
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Overweight and obesity in children has reached epidemic proportions in recent decades, and even the youngest age groups are affected. Excess weight during childhood often follows the child into adulthood and is associated with diseases such as cardiovascular diseases and type 2 diabetes mellitus. In addition, excess weight often leads to health problems already during childhood. Childhood obesity is therefore one of the greatest public health challenges of the 21st century.AIM: The overall aim was to study growth patterns and early risk factors for overweight, obesity and an elevated waist-to-height ratio (WHtR) in preschool children. The specific aims were to: examine early body mass index (BMI) and WHtR growth patterns and their ability to predict overweight or obesity in children at 5 years of age (Paper I); examine if BMI and WHtR growth patterns from an early age could identify children with an elevated WHtR at 5 years of age by using standard deviation score(s) (SDS) in children classified according to WHtRSDS at 5 years of age. Another aim was to study the association between BMISDS and WHtRSDS at 5 years of age (Paper II); examine nutrition- and feeding practice-related risk factors for rapid weight gain during the first 0–6 months and the following 6–12 months (Paper III); examine the association between potential early risk factors and an elevated WHtR, defined as WHtRSDS ≥ 1 at 5 years of age, and examine whether similar associations also were found for overweight or obesity at the same age (Paper IV).METHODS: This project was part of the population-based birth cohort study the Halland Health and Growth Study, including 2,666 children born in the county of Halland in the southwestern part of Sweden between October 2007 and December 2008. Weight, height and waist circumference were measured at nine time points starting at birth. At every measurement point the parents filled in questionnaires regarding their child’s nutrition, health and lifestyle and also background information about the family.RESULTS: We found that children with overweight or obesity at 5 years of age could be identified already from an early age by significantly higher mean BMISDS and WHtRSDS than corresponding values in children with normal weight or underweight. BMI was sufficient for predicting overweight or obesity at 5 years of age and WHtR did not add any further information in this prediction.Children with a WHtRSDS ≥ 1 at 5 years of age could be identified already from an early age by significantly higher mean BMISDS and WHtRSDS than corresponding values in children with a WHtRSDS < 1. When comparing WHtRSDS and BMISDS at 5 years of age, 55% of the children with an elevated WHtRSDS had normal BMISDS.Rapid weight gain was more common during the first 6 months of the first year than during the next 6 months. Bottle-feeding and nighttime meals containing formula milk were associated with rapid weight gain between 0 and 6 months. Breastfeeding was negatively associated with rapid weight gain during the same period.Rapid weight gain during 0–6 months and also maternal pre-pregnancy BMI and paternal BMI were associated with a WHtRSDS ≥ 1 at 5 years of age. Rapid weight gain during both 0–6 and 6–12 months and also maternal pre-pregnancy BMI, were associated with overweight or obesity at 5 years of age.CONCLUSION: This thesis showed that BMI was sufficient for predicting overweight or obesity at 5 years of age, and WHtR did not add any further information to this prediction. For identification of children with an elevated WHtR, BMI classification missed every second child, indicating that WHtR adds value in children who may need further investigation regarding cardiometabolic risk factors. Risk factors operating before pregnancy and early in life increase the risk of early rapid weight gain, an elevated WHtR and overweight or obesity at 5 years of age and bottle feeding, nighttime meals, early rapid weight gain as well as parental overweight are potential modifiable risk factors in this development.
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| 4. |
- Pietilä Holmner, Elisabeth, 1953-
(författare)
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Multimodal rehabilitation of patients with chronic musculoskeletal pain, focusing on primary care
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Chronic pain is a complex condition that has consequences both for individual people and for society. The individual often experiences impact on function, activity and participation. Society is affected by high healthcare and sick leave costs and a loss of workforce. Multimodal rehabilitation programmes (MMRP) have mainly been provided through specialist care but it is now also available through primary care. The overall aim of this thesis was to evaluate the effects of MMRP in patients with chronic musculoskeletal pain and to explore patients’ and healthcare professionals’ experiences of MMRP.Study I: Aim: To evaluate the effects of an interdisciplinary team assessment and MMRP for patients with chronic pain in a specialist care setting. Design: Longitudinal cohort study. Method: Pain intensity, pain dimensions, anxiety and depression were measured at assessment and at the start and end of MMRP. A total of 93 women were evaluated. Result: Pain and pain-related measures were significantly improved both after the interdisciplinary assessment and after MMRP.Study II: Aim: To explore healthcare professionals’ experiences of MMRP in primary care. Design: Individual interviews, analysed with qualitative content analysis. Method: Fourteen healthcare professionals (11 women, 3 men) were interviewed about their work with MMRP. Result: Healthcare professionals considered that MMRP was useful but also challenging. It was difficult to select appropriate patients, and health care professionals felt they were torn between following healthcare legislation and the goals of MMRP. They had to deal with ethical dilemmas as well as decide what constitutes good results.Study III: Aim: To explore patients’ experiences of participating in MMRP in primary care. Design: Individual interviews, analysed with qualitative content analysis. Method: Twelve former patients (7 women and 5 men) were interviewed about their experiences of MMRP in primary care. Result: Patients in primary care experienced a complex, ongoing process of accepting chronic pain. Obtaining redress, learning about chronic pain, and experiencing fellowship with others with the same condition contributed to the acceptance process.Study IV: Aim: To evaluate the effects of MMRP in primary care at one-year follow-up for all patients together and for men and women separately and to identify predictive factors for being employable at follow-up. Design: Prospective longitudinal cohort study. Method: Pain, physical and emotional functioning, coping, health-related quality of life, work-related factors, sick leave extent and sickness compensation were evaluated prior to and one year after MMRP in 234 patients, 34 men and 200 women. Result: All patients improved significantly in most measures at one-year follow-up, and the effect was larger in women. Sick leave decreased while no significant difference was found for total sickness compensation. Patients’ self-reported rating of current work ability before MMRP was significantly associated with being employable at follow-up.General conclusions and implications: MMRP seems to be effective for patients with chronic musculoskeletal pain, both in specialist care and in primary care. MMRP was more effective for women than for men, and the reasons for this need to be investigated further. An interdisciplinary team assessment could also be beneficial for decreasing pain and pain-related measures. Patients in primary care experience a complex, ongoing process of accepting chronic pain. Healthcare professionals have to deal with conflicting emotions with regard to different commitments from healthcare legislation and the goals of MMRP.
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