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  • Public defence: 2018-01-26 12:24 Baertlingsalen, Halmstad
    Franck, Alina
    Linnaeus University, Faculty of Health and Life Sciences, Department of Psychology.
    The junior-to-senior transition in Swedish athletes: A longitudinal study2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This dissertation project was an exploration of junior-to-senior transition (JST) processes in Swedish sport club athletes based on holistic, developmental, and ecological perspectives. It consists of two multi-level studies covered by four separate articles. The first study is a quantitative longitudinal investigation of athletes’ transitional and personal variables during a two-and-a-half-year period including five measurements times (N = 101). The second study is a qualitative exploration of the JST pathways of four athletes who were also participants of the first study; the athletes’ transition narratives could be related to the previously discovered dynamics of their JSTs.

         The first article (1a), presenting study 1, is focused on identifying profiles of athletes in the JST based on some of their personal characteristics (athletic identity, self-esteem, and goal orientation) followed by a description of the JST pathways relevant to their profiles. The latent profile analysis resulted in three athlete profiles. Athletic identity appeared to be a key personal characteristic that influenced the dynamics of the JST adjustment. Different styles of coping strategies were also associated with different JST pathways.

         The second article (1b), presenting study 1, is aimed at identifying adjustment patterns in the JST based on athletes’ dynamics of adjustment during a two-and-a-half-year period, and describes the athletes’ demographics, personal and transitional characteristics at the beginning of the JSTs that were related to the different adjustment patterns. The latent profile analysis on athletes’ perceived degree of adjustment provided three profiles with different adjustment patterns (i.e., progressive, regressive, sustainable). Further analyses (descriptive statistics and Cohen’s d) showed that keeping a primary focus on sport (without ignoring other spheres of life), having a strong athletic identity, and a high motivation to reach the senior level were (to different degrees) relevant for both progressive and sustainable adjustment patterns.

         The first article (2a), presenting study 2, qualitatively explores two individual sport athletes’ (a male swimmer and a female tennis player) JST transition pathways, emphasising psychosocial factors that were perceived as facilitating and debilitating for the transition process. Narrative type interviews were used, and the holistic-form structural analysis provided a central storyline – a performance narrative – that was common for both athletes and two individual side storylines that were the swimmer’s effort and relationship narrative and the tennis player’s injury and reorientation narrative. Both athletes experienced various crossroads and shared perceptions of the factors facilitating coping (e.g., family, some coaches, elite sport club environment), but their reflections on the debilitating psychosocial factors of their JSTs were more individualistic than their views on the facilitating factors..

         The second article (2b), presenting study 2, has the same objectives and the same methodology as article 2a, but focuses on two team sport athletes’ (a male football player and a female basketball player) JST pathways. The football player’s JST path developed into a performance and family narrative, and the basketball player’s reflections on the transition process formed an enjoyment and relationship narrative. The players’ JST paths were lined with different crossroads, and throughout the transitions they perceived the key facilitating persons to be their families (e.g., parents, grandparents, siblings) and teammates, but some of the coaches’ behaviors were perceived as debilitating factors.

    Major contributions to knowledge in this dissertation project include: (a) considering the JST (longitudinally) as a process involving dynamics and interactions of the transition demands, coping strategies, personal and environmental resources, and barriers influencing the JST outcome; (b) supporting the athletic career transition model in combination with the holistic, developmental, and ecological perspectives as adequate frameworks to study the JST; (c) suggesting that the integrated JST framework supported by the empirical findings can be used in the future research; (d) demonstrating significant variations in the JST pathways and adjustment patterns on the sub-group level (study 1) and also on the individual level (study 2); and (e) providing context-specific recommendations for different levels of the Swedish sport system for optimizing Swedish sport club athletes’ JSTs and supporting their continued sport participation on either the senior elite or the recreational level.

  • Public defence: 2018-02-01 10:00 N1017, Växjö
    Hu, Min
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Studies of the fibre direction and local bending stiffness of Norway spruce timber: for application on machine strength grading2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Machine strength grading is a production process in the sawmill industry used to grade sawn timber boards into different strength classes with specific characteristic values of the bending strength, modulus of elasticity (MOE) and density. These properties are called grade determining properties. Each of these is predicted on the basis of a statistical relationship between the property and a so-called indicating property (IP), which is based on non-destructively assessed board properties. In most cases, the prediction of strength is crucial for the grading. The majority of commercial grading machines rely on a statistical relationship of strength to an IP, which is either a global dynamic MOE or an averaged flatwise bending MOE measured over a board length of about one meter. The problem of today’s machine strength grading is that the accuracy of the strength prediction is rather poor with a coefficient of determination of about R2 ≈ 0.5 − 0.6. One consequence of this is that much of the strength potential of timber is unused.

    The intention of this research is to contribute to a long-term goal, which is development of a method for prediction of bending strength that is more accurate than the methods available today. The research relies on three hypotheses. First, accurate prediction of bending strength can be achieved using an IP that is a localized MOE value (determined over a short length) that represents the lowest local bending stiffness of a board. Second, knowledge of the local bending stiffness with high resolution along a board’s longitudinal direction can be established on the basis of fibre direction within the board in combination with dynamic MOE. Third, fibre directions in the interior of a board can be determined by application of fibre angle models utilizing data of fibre directions on the board’s surfaces obtained from tracheid effect scanning. Following these hypotheses, this work has included laboratory investigations of local material directions, and development of models for fibre directions of the interior of boards. The work also included application of one-dimensional (1D) analytical models and three-dimensional (3D) finite element models of individual boards for the mechanical behaviour, analysis of mechanical response of boards based on experiments and based on the suggested models. Lastly, the suggested models were evaluated by comparisons of calculated and experimentally determined local bending stiffness along boards, and of predicted and experimentally determined bending strength.

    The research contributes with in-depth knowledge on local fibre directions close to knots, and detailed information on variation of the local bending stiffness in boards. Moreover, fibre angle models for fibre directions in the interior of boards are presented. By application of the fibre angle models in the 3D model of the whole board, the local bending stiffness along timber boards can be determined over a very short length (l < 50 mm). A comparison with results determined on an experimental basis show a very close similarity implying that the applied models are sufficient to capture the variation of local bending stiffness, caused by knots and fibre distortions, with very high accuracy. Furthermore, it is found that by means of IPs derived using the suggested models, bending strength can be predicted with high accuracy. For a timber sample comprising 402 boards, such IPs results in coefficient of determination as high as R2 = 0.73. However, using IPs based on the 3D finite element model did not improve the R2 value achieved when using the IPs based on the 1D model.

  • Public defence: 2018-02-02 13:30 Fullriggaren, Kalmar
    Broman, Elias
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ecology and evolution of coastal Baltic Sea 'dead zone' sediments2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since industrialization and the release of agricultural fertilizers began, coastal and open waters of the Baltic Sea have been loaded with nutrients. This has increased the growth of algal blooms and because a portion of the algal organic matter sinks to the sea floor, hypoxia has increased. In conjunction to this, natural stratification of the water column makes the bottom zones especially prone to oxygen depletion due to microbes using oxygen and organic matter to grow. Hypoxia (<2 mg/L O2) and anoxia (no oxygen) are deadly for many organisms and only specialists (typically some microorganisms) are able to survive. Due to the harsh conditions these bottom zones are commonly referred to as 'dead zones'. The focus of this thesis was to look closer at the microbial community changes upon degradation of algal organic matter and the effect of oxygenating coastal Baltic Sea 'dead zone' sediments on chemistry fluxes, phyto- and zooplankton, the microbial community structure, and microbial metabolic responses. Results from field sampling and incubation experiments showed that degradation of algal biomass in nutrient rich oxic sediment was partly related to the growth of archaea; that oxygenation of anoxic sediments decreased stored organic matter plus triggered hatching of zooplankton eggs increasing the benthic-pelagic coupling; and resting diatoms buried in hypoxic/anoxic sediment were alive and triggered to germinate by light rather than oxygen. Changes in the microbial community structures to oxygen shifts were dependent on the historical exposure to oxygen and that microbial generalists adapted to episodic oxygenation were favored during oxygen shifts. Facultative anaerobic sulfur/sulfide oxidizing bacterial genera were favored upon oxygenation of hypoxic/anoxic sediment plus sulfur cycling and nitrogen fixation genes were abundant. Finally, it was discovered that oxygenation regulates metabolic processes involved in the sulfur and methane cycles, especially by metabolic processes that results in a decrease of toxic hydrogen sulfide as well as the potent greenhouse gas methane. This thesis has explored how 'dead zones' change and develop during oxygen shifts and that re-oxygenation of ‘dead zones’ could bring favorable conditions in the sediment surface for reestablishment of new micro- and macroorganism communities.

  • Public defence: 2018-02-02 15:57
    Jani, Yahya
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Landfills and glass dumpsites as future bank accounts of resources – waste characterization and trace elements extraction2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Environmental pollution and health threats as well as scarcity of raw materials, water, food and energy are among the main challenges our world are now facing. Simultaneously, landfills and open dumpsites still are the dominant global waste disposal option even with their long term environmental impacts in case of greenhouse gases and contaminated leachates. In this thesis, landfill mining is suggested as a tool that should be included in an enhanced circular economy model (repair, reuse and recycle + extract and recovery) by considering the extraction/recovery of the lost materials in landfills and dumpsites as secondary resources.

    Characterization data (composition and physicochemical properties) is considered as a vital source for information for: i. the valorization of excavated wastes, ii. to explore potential hazards and iii. as an important tool for theassessment of the waste management systems and policies. In this thesis,excavated wastes from a classic landfill (Högbytorp in Sweden), a landfill buildup according to the European Directive requirements (Torma in Estonia) andhazardous glass dumpsite (Pukeberg in Sweden) was characterized as a centralstep in exploring the potential of recovering of valuables. In addition, the extraction of trace elements from waste glass and different finefractions were also investigated. The reduction-melting method was developedto extract hazardous concentrations of trace elements from old art and crystalglasses with more than (99%) of recovery of Pb, Cd and As. While threechelating agents (EDTA, DTPA and NTA) were used to extract Pb, Cd, Asand Zn from fine fraction (<2 mm) sampled from Pukeberg glasswork with anextraction efficiency of (40%). Besides, the fractionations of the metals Cu, Znand Cr in the fine fractions (<10 mm) excavated from Högbytorp and Tormalandfills were studied by using a modified sequential extraction procedure.

    The findings of this thesis highlighted the need to consider the dumped wastesas secondary resources and landfills and dumpsites as future bank accounts offuture raw materials instead of being burden to the human health and theenvironment.

    The full text will be freely available from 2018-02-05 15:58