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  • Public defence: 2018-12-20 10:00 C326, Sundsvall
    Ziaei, Reza
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Prevalence and Correlates of Health Risk Behaviors among High School Adolescents in Iran: With focus on Water-pipe Smoking, Suicide Ideation, Physical Activity and Nutrition2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background: Adolescence is a transitional stage from childhood into adulthood and many habits, with long-term implications for health, from this period of life can continue into adulthood. Identifying risk factors related to health risk behaviors is therefore an important part of health promotion. The main aim of this thesis was to analyze the prevalence and correlates of health risk behaviors among 15-17 year old high school adolescents in Iran. The risk behaviors explored in Papers I–IV include waterpipe smoking, suicide ideation, physical inactivity and sedentary behavior, and nutritional habits.

    Methods: Two-stage cluster sampling was used to select representative high schools and classes in the Iranian city of Tabriz. At the first stage, high schools were selected with a probability proportional to the enrollment size. At the second stage, classes were randomly selected, and all students in these selected classes were eligible to participate in the study. Overall, thirty high schools, including sixteen girls’ and fourteen boys’ high schools, ninety classes (grades 9 to 11) and 1,517 students, including 727 boys (47.9%) and 790 (52.1 %) girls participated in the study. The participants’ (students’) response rate was 84.27 %. A reliable, valid and anonymous self-administered Persian Version of the Global School-Based Student Health Survey (GSHS) questionnaire was used for data collection. Statistical methods used were Chi- square test, Fisher exact and multivariate logistic regression analyses.

    Results:

    Water pipe smoking: Overall, 21.6 % of students were classified as ever WP smokers and 9.7% as current smokers. Ten percent of students had started WP smoking when younger than 12. Ninety-one percent of current WP smokers smoked one session per day, 49% smoked at a café (Ghahvekhaneh). Ninety- five percent of students reported that their age did not prevent them from being served a WP. Ninety-one students out of 147 reported that they did not notice any health warning on the WP tobacco packages. Seven percent of students out of 1,517 participants reported that they would accept a WP if offered by their friends. Being in the third grade of high school, having experienced cigarette smoking, even one or two puffs, and accepting a WP offered by close friends showed significant odds ratios for ‘ever WP smokers’. Accepting a WP offered by close friends and gender (female) showed significant odds ratios for current WP smokers.

    Suicide ideation: Four percent of students had seriously considered attempting suicide in the past 12 months. Thirteen point two percent of students reported that they wanted to use alcohol or other drugs when they were worried. The results also revealed that 8.8% of students had been sexually abused. Also, 20.6% declared that they had been bullied in the past 30 days.

    Being worried, being a current cigarette smoker, consuming alcohol or other drugs and being sexually abused were significantly associated with suicide ideation.

    Physical activity/inactivity and sedentary behavior: The prevalence of physical inactivity (<5 days/Weeks) was 72.2% and sedentary behavior (sitting ≥3 h or more) 71.4%. Being female, having a higher BMI (being overweight or obese), walking/cycling to or from school on 1-4 days, sedentary behavior, low vegetable intake, being the victim of bullying, lack of parental support, peer support, and parental connectivity (protective factors) were directly associated with physical inactivity. Walking/cycling to or from school on 5-7 days was negatively associated with physical inactivity.

    Walking/cycling to or from school on 1-4 days, being physically inactive, inadequate fruit intake, and being bullied were positively associated with sedentary behavior.

    Fruit and vegetable intake: The prevalence of fruit intake was 76.1% (≥ 2 times/daily) and vegetable intake 23% (≥ 3 times /d). Low fruit consumption was associated with being an 11th grade student, sedentary behavior (sitting ≥3h/d), low intake of vegetables (intake < 3 daily), low or lack of parental support, low or lack of peer support, and the lack of enough food (hunger) at home. Low vegetable consumption was associated with higher BMI (overweight or obese), low consumption of fruit (< 2 daily), lack of peer support, and physical inactivity.

    Conclusion: Identified correlated factors (risk factors) should be taken into consideration by public health authorities in the development and implementation of interventions aimed at promoting health among students in the related areas.

  • Public defence: 2019-01-11 10:15 O102, Sundsvall
    Vilches, Ana Paola
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of Bio-Ash Amendments on the Metabolism of Ectomycorrhizal Fungi: A Method Development and Metabolomic Study2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Forest ecosystems have played a fundamental role in the development of our society. Since the beginning of the civilization, forest have provided us with wood as a product for construction, tools, furniture and domestic heating. The well-being of the forest is therefore fundamental to our existence. Today, our growing societies have increased energy needs; the resulting depletion of fossil reserves and the effects of their use has again shown how the forest is among the most important alternatives for sustainability of our ecosystem. In order to responsibly make this resource a key part of our energy and material supply, we need to understand how forestry practices influence the different processes taking place in the forest ecosystems.

    The use of raw material from forest as energy source produces huge amounts of ash. The ash contains the base cations that have once been translocated from soil to the upper parts of the trees. Ash recycling has therefore been suggested as a measure to counteract soil acidification due to extensive harvest. Since spreading of ash can have great effects on the forest, it is important to understand which these effects are and how big they might be.

    This thesis focuses on the effects that such an ash recycling may have on the metabolism of ectomycorrhizal fungi; that is, fungi that are able to colonize root of trees, and contribute to the acquisition of nutrients and water from soil. The work presented here utilized an in vitro metabolomic approach on eight species of ectomycorrhizal fungi normally found in boreal forests. A targeted metabolomic study addressed the effects of ash amendments on growth, external pH and the exudation of low molecular mass organic acids, amino acids and hydroxamate siderophores. This was complemented by an untargeted metabolomic study to address the effects of ash amendment on the general metabolism of the fungal species.

    Analyses were performed with well-established chemical methods, and some that had to be developed specifically for this thesis work. A method for the analysis of amino acids without derivatization and yet compatible with mass spectrometry had to be developed and validated. The result was a robust method that works well with external calibration, shows good long-term stability, relatively low detections limits and high sample throughput. A screening protocol for the determination of siderophores from mass spectrometry data was also established.

    The metabolomic studies showed that bio-ash amendment increased the exudation of low molecular mass organic compounds from all the studied species. This means that the species tended to exude more of the same compounds compared to the controls without ash. In some cases, the bio-ash also triggered the exudation of new compounds. There was some exceptions, though; bio-ash amendment had negative effects on the exudation of certain metabolites, but these negative effects were of lower magnitude compared to the positive effects.

    Both metabolomics studies showed a differentiation between the ascomycetes and the basidiomycetes species. The targeted metabolomic study, indicated a trade-off in the utilization of carbon for accumulation of biomass or for the exudation of low molecular mass organic compounds, in which the ascomycetes accumulated more carbon as biomass compared to the basidiomycetes. According to the untargeted metabolomic study, the ascomycetes species presented the greatest number of metabolites that were influenced significantly by ash treatment, either as increase or decrease.

    Adding extracted ash to the culturing medium at the beginning of the experiment increased the pH, but this was counteracted by species metabolism as exudation of organic acids correlated with a drop in external pH. Ash treatment triggered the total exudation of low molecular mass organic acids in five of the eight studied species and especially in Cortinarius glaucopus. Ash treatment also triggered the exudation of amino acids from Tomentellopsis submollis and ferricrocin from Hymenoscyphus ericae.

    Of note was that no metabolite significantly influenced by ash was found to be common to all species, indicating that the ash amendments mainly affected the secondary metabolism under the culturing conditions used. Additionally, the ascomycetes Hymenoscyphus ericae exuded the greatest number of metabolites affected by ash that were exuded only by a single species. Conversely, Piloderma olivaceum exuded the largest number of unique metabolites not influenced by ash.

  • Public defence: 2019-01-15 09:15 Q221, Östersund
    Klingvall Ek, Rebecca
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Quality Management and Mechanical Engineering.
    Electron beam melting: Impact of part surface properties on metal fatigue and bone ingrowth2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Abstract

    The aim of this thesis is to investigate aspects on how additive manufacturing (AM) contributes to functional bone implants with the use of the electron beam melting (EBM) technology. AM manufactures parts according to computer-aided design, and the EBM technology melts powder using an electron beam, which acts similar to a laser beam. The topics discussed in this thesis are related to surface roughness that originate from the melted metal powder, and the thesis tries to define some aspects that affect implant functionality. Process parameters steering the electron beam and biocompatibility arising from the surface texture were the initial parts of the PhD studies, and the other half focused on post-processing and fatigue, which are important for medical and industrial applications. There are six studies in this compilation thesis. They are abbreviated as P - process parameters, M - medical applications, and F - fatigue. Studies P, M2, F2, and F3 are journal articles, and M1 and F1 are conference proceedings.

    Study P used design of experiments to investigate how process parameters affect the surface roughness of as-built EBM-manufactured parts and concluded that beam speed and energy (current) were the most important parameters that influence the surface roughness.

    In studies M1 and M2, EBM-manufactured specimens of cobalt-chromium and titanium alloys were used to evaluate biocompatibility. The blood chamber method quantified the reactions of the human whole blood in contact with the metal surfaces, and the results showed how the as-built EBM surface roughness contributed to coagulation and bone healing.

    Rotating beam fatigue equipment was used in studies F1–F3 and study F1 discussed the size effect on fatigue loaded as-built specimens and included specimens with different sizes and with or without hot isostatic pressing (HIP). Study F2 compared as-built and machined specimens and study F3 investigated how Hirtisation, which is a patented electrochemical surface treatment, and HIP affect the fatigue properties that originate from the electrochemical polishing surface topography. The studies showed that a decreased surface roughness increased the fatigue resistance while the stress concentrations (Kt) in the surface of EBM-manufactured specimens decreased.

    The thesis concludes that EBM-manufactured as-built surfaces are suitable for direct contact with the bone, and that HIP does not improve the fatigue resistance of parts with as-built surfaces, where crack initiation starts at notches.