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| 2. |
- Andersson, Henrik, 1975-
(författare)
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Position Sensitive Detectors : Device Technology and Applications in Spectroscopy
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with the development, processing and characterization of position sensitive detectors and, in addition, to the development of compact and cost effective spectrometers. Position sensitive detectors are used to measure, with great accuracy and speed, the position of a light spot incident on the surface. Their main use is for triangulation, displacement and vibration measurements. A type of position sensitive detector based on the MOS principle and using optically transparent indium tin oxide as a gate contact has been developed. This type of detector utilizes the MOS principle where an induced channel forms beneath the gate oxide in the surface of the Silicon substrate. One and two dimensional detectors have both been fabricated and characterized. The first measurements showed that the linearity did not fulfil expectations and it was suspected that stress induced by the gate contact could be the reason for the seemingly high nonlinearity. Further investigations into both the p-n junction and the MOS type position sensitive detectors lead to the conclusion that the indium tin oxide gate is responsible for inducing a substantial stress in the surface of the detector, thus giving rise to increased position nonlinearity. The heat treatment step which was conducted was determined to be critical as either a too short or too long heat treatment resulted in stress in the gate and channel leading to position nonlinearity. If a correctly timed heat treatment is performed then the detector’s linearity is in parity with the best commercial position sensitive detectors. In addition, the development of very small, compact and cost effective spectrometers has been performed with the aim of constructing devices for use in the process industry. The development of a wedge shaped array of Fabry-Perot interferometers that can be mounted directly on top of a detector makes it possible to construct a very compact spectrometer using the minimum amount of optics. This wedge interferometer has been evaluated by means of array pixel detectors and position sensitive detectors for both the infrared and the visible wavelength ranges. When used with a position sensitive detector it is necessary to use a slit to record the intensity of the interferogram for many points over the detector, equivalent to pixels on an array detector. Usually the use of moving parts in a spectrometer will impose the use of high precision scanning mechanisms and calibration. By using a position sensitive detector for the interferogram readout both the position and the intensity are known for every measurement point and thus the demands placed on the scanning system are minimized.
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| 3. |
- Aronsson, K. Andreas
(författare)
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Effects of wood ash on freshwater organisms and aquatic forest ecosystems
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood ash application (WAA) has been recommended mainly for two reasons; i) to avoid depletion of minerals in the soil due to whole tree harvest in the forestry and ii) to mitigate harmful effects of acidification of soil and surface waters. In conclusion, the effects on terrestrial ecosystems and, especially, tree growth, can be attributed to the properties of the ash, the dose applied and the specific site at which the ash is applied. The research conducted on the effects of WAA on limnological ecosystems is very limited, and the major purpose of the present thesis was to gain knowledge of the effects of wood ash to different freshwater organisms, and the more comprehensive, limnological effects of WAA in the first stream in Bispgården, Sweden. Effects of wood ash solutions on the unicellular alga Euglena gracilis Klebs, the amphipod Gammarus pulex L., and the moss Fontinalis antipyretica Hedw. were investigated under laboratory conditions. Common in all three species was the decline in performance (growth/velocity/respiration/oxygen evolution) when the concentration of wood ash exceeded 5 g/l and no adjustment of pH was done (alkaline solution). In contrast, different movement parameters (motility, upwards swimming and velocity) in E. gracilis (neutral conditions), and increased growth of F. antipyretica with increased concentrations of wood ash indicated that nutrients in the ash was bioavailable for these organisms. There was no evidence of toxic effects on the organisms from metals or other compounds as a result from exposure to wood ash solutions in the present studies. The field study was conducted in a forest area close to Bispgården, about 100 km NW from Sundsvall, Sweden. The catchment area (50 ha) of the stream Fanbergsbäcken was treated with wood ash in September of 2004 (3,000 kg/ha;selfhardened crush-ash). In general, both biological (diatoms) and chemical (pH, alkalinity, and aluminum (Al) measurements) indicators have shown no significant effect on acidification parameters from the addition of wood ash. There was, however, evidence of an increased pH during spring flood, accompanied with a decrease in the frequency of low pH values (<5.6) during spring flood. In addition to this, alkalinity was significantly higher in the period 2005-2006, compared to that of 2003. High concentrations of toxic forms of Al repeatedly occured in the stream Fanbergsbäcken, and the WAA did not affect the frequencies of high concentrations of toxic Al forms (<50 μg/l). Both the moss F. antipyretica and the leaves from Alnus incana displayed increased potassium (K) concentrations, although other nutrients did not increase from WAA. In conclusion, no evidence of WAA being effective in restoring or improving the ecological status of freshwater environments has been established, either in the literature or in the present field study. On the other hand, there were no indications of harmful effects due to WAA, either. However, we still do not know the effects of wood ash on several organisms (predominantly invertebrates) inhabiting small ponds and other, temporary or permanent, freshwater ecosystems. In the context of WAA, these environments and organisms have not attended any attention in the research published to date, and future studies are strongly encouraged.
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| 4. |
- Berg, Jan-Erik, 1957-
(författare)
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Wood and fibre mechanics related to the thermomechanical pulping process
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main objective of this thesis was to improve the understanding of some aspects on wood and fibre mechanics related to conditions in the thermomechanical pulping process. Another objective was to measure the power distribution between the rotating plates in a refiner. The thesis comprises the following parts: –A literature review aimed at describing fracture in wood and fibres as related to the thermomechanical pulping process –An experimental study of fracture in wood under compression, at conditions similar to those in feeding of chips into preheaters and chip refiners –An experimental study of the effect of impact velocity on the fracture of wood, related to conditions of fibre separation in the breaker bar zone in a chip refiner –A micromechanical model of the deterioration of wood fibres, related to the development of fibre properties during the intense treatment in the small gap in the refining zone –Measurements of the power distribution in a refiner. The fracture in wood under compression was investigated by use of acoustic emission monitoring. The wood was compressed in both lateral and longitudinal directions to predict preferred modes of deformation in order to achieve desired irreversible changes in the wood structure. It was concluded that the most efficient compression direction in this respect is longitudinal. Preferable temperature at which the compression should be carried out and specific energy input needed in order to achieve substantial changes in the wood structure were also given. The fibre separation step and specifically the effect of impact velocity on the fracture energy were studied by use of a falling weight impact tester. The fracture surfaces were also examined under a microscope. An increase in impact velocity resulted in an increase in fracture energy. In the thermomechanical pulping process the fibres are subjected to lateral compression, tension and shear which causes the creation of microcracks in the fibre wall. This damage reduces the fibre wall stiffness. A simplified analytical model is presented for the prediction of the stiffness degradation due to the damage state in a wood fibre, loaded in uni-axial tension or shear. The model was based on an assumed displacement field together with the minimum total potential energy theorem. For the damage development an energy criterion was employed. The model was applied to calculate the relevant stiffness coefficients as a function of the damage state. The energy consumption in order to achieve a certain damage state in a softwood fibre by uniaxial tension or shear load was also calculated. The energy consumption was found to be dependent on the microfibril angle in the middle secondary wall, the loading case, the thicknesses of the fibre cell wall layers, and conditions such as moisture content and temperature. At conditions, prevailing at the entrance of the gap between the plates in a refiner and at relative high damage states, more energy was needed to create cracks at higher microfibril angles. The energy consumption was lower for earlywood compared to latewood fibres. For low microfibril angles, the energy consumption was lower for loading in shear compared to tension for both earlywood and latewood fibres. Material parameters, such as initial damage state and specific fracture energy, were determined by fitting of input parameters to experimental data. Only a part of the electrical energy demand in the thermomechanical pulping process is considered to be effective in fibre separation and developing fibre properties. Therefore it is important to improve the understanding of how this energy is distributed along the refining zone. Investigations have been carried out in a laboratory single-disc refiner. It was found that a new developed force sensor is an effective way of measuring the power distribution within the refining zone. The collected data show that the tangential force per area and consequently also the power per unit area increased with radial position. The results in this thesis improve the understanding of the influence of some process parameters in thermomechanical pulping related wood and fibre mechanics such as loading rate, loading direction, moisture content and temperature to separate the fibres from the wood and to achieve desired irreversible changes in the fibre structure. Further, the thesis gives an insight of the spatial energy distribution in a refiner during thermomechanical pulping.
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| 5. |
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| 6. |
- Blid, Mats, 1951-
(författare)
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Ett folkhem för alla? : Kommunala insatser mot hemlöshet
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overarching aim of this dissertation is to explore and describe Swedish local authorities’ measures to prevent and manage homelessness; how these measures diverge between different municipal categories; what factors predict homelessness, provisions of accommodation and cov-erage rates between the number of accommodations and the respective municipalities’ housing interventions. Measures studied are policies and housing interventions. The housing interventions re-ferred to here are those provided by or through the social welfare authorities to persons living with unstable housing or who are homeless. The interventions can be divided into two main categories: 1) preventive interventions in the form of daily-life support, usually in the form of personnel support in the individual’s own apartment, designed to help persons at risk of becom-ing homeless to remain housed and prevent eviction; 2) accommodation support for persons who are already homeless and in need of housing. Such accommodations may be more or less temporary, more or less integrated and include a greater or lesser amount of care. Two sets of data were collected for the study: 1) a case study of two category-housing programmes using both qualitative and quantitative data; 2) a survey of 147 randomly chosen municipalities (about half of the municipalities in Sweden) to explore the prevalence and charac-teristics of policies and housing interventions. Findings from the case study show that special-category housing has positive direct effects on the housing stability of the residents and their feelings regarding their quality of life, but does not have a direct effect on their substance misuse. Moreover, the increased housing stability seems to be more a direct effect of the person having stayed on the programme, rather than a long-term effect. Furthermore, although their quality of life improves, the residents still experi-ence a lack of belonging and feel that their lives lack meaningful content. On the national level, the findings show that an array of housing interventions divided into 12 sub-categories is offered to counteract homelessness. These categories vary along two central dimensions: care and normality. The two most frequent types of housing interventions in all types of municipalities are daily-life support and social contracts. Other housing interventions are marginal compared with these two. There is greater fluctuation between municipalities in the level of care provided than in the level of normality. Furthermore, the more densely populated municipalities are more highly engaged in developing housing policies and the administrative means to handle them. Such policies, however, seem to decrease the level of normality without promoting levels of care. When exploring factors that predict homelessness, the findings show that urbanisation is central to understanding variations in homelessness, not only in the largest cities but also in less densely populated areas. In addition, higher rent levels and more of aggregated psychiatric prob-lems in the municipality seem to increase homelessness. The apartment rate and the proportion of public housing within the stock of apartments are both important for the possibility to pro-vide accommodations. Moreover, the proportion of single-parent households seems to enhance the need to provide such accommodations. Political majority and the functional organisation of the social services both seem to have an impact on the coverage rates. Thus, the findings indicate that the municipalities have various options for managing factors that impact on the homeless-ness rate. Keywords: housing interventions, level of care, level of normality, policies, municipality, predicting homelessness
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| 7. |
- Borglund, Erik A.M. 1969-
(författare)
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Design for Recordkeeping: Areas of Improvement
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is about problems related to design of information systems in which records are born and managed. The proactive approach has been derived from new archival theories suited for electronic recordkeeping, and implies that electronic records must, at the time of creation fulfil their current and future requirements. Information systems where records are born and managed should, based upon a proactive approach, meet recordkeeping requirements. This thesis is based upon a four-year research effort and consists of seven research articles that present the results of the research. The objective is to contribute to knowledge of design recommendations for information systems, in which records are born and managed. The main result of this thesis is identification of five areas that can affect and improve the design of information systems in which records are born and managed. First: A set of empirically and theoretical grounded characteristics of records are presented. Those characteristics have to be complemented with organization-defined characteristics. Second: this research has contributed a conceptualization of use of records and users of records. The notion of known use/user, and unknown use/user has been introduced. Design becomes difficult because requirements of unknown users are difficult to conceptualize. Third: The Recordkeeping Quality Assessment model (RQAM) is presented. The model implies a holistic quality approach to recordkeeping, and intends to be used as a basis for quality assessment, and as a reference model in design situations to achieve high recordkeeping quality. Fourth: Two dominant different views on records are presented. Private organizations appraise records principally upon business values, and public organisations base their appraisal criteria upon accountability and legislative values. The two views on records should be brought into one view and form a risk management-like appraisal. Fifth: Proactivity is a way of thinking and should be applied on several levels in the recordkeeping environment: to the electronic record, to the information system where the electronic record is born and managed, to the organization, and to the user.
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| 8. |
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| 9. |
- Bäckström, Ingela, 1963-
(författare)
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On the Relationship between Sustainable Health and Quality Management : Leadership and organizational behaviours from Swedish organizations
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sickness absence not only causes significant costs for organizations but also leads to other negative consequences for individuals and societies. Previous research has shown that working with organizational values within Quality Management affects job satisfaction and results in increased profitability and customer satisfaction. There would, in addition, seem to be great gains if managers, by working with Quality Management, can manage to establish sustainable health among co-workers. The purpose of the research described in this thesis was to examine how Quality Management could be practised in order to support sustainable health among co-workers and what it is within Quality Management that influences sustainable co-worker health. Accordingly, the purpose was also to contribute to the understanding of the relation between sustainable health and Quality Management. To fulfil this purpose, three research questions were asked. The results are described in three parts related to the three research questions and are the product of six case studies carried out in seven different organizations. Interviews with managers and workshops with co-workers were carried out to investigate how Quality Management can be practised within organizations in order to promote sustainable co-worker health. These investigations took place in four organizations that had received awards. Three had been awarded for their excellence in leadership, work environment and co-workership, along with improved profitability; one for its successful implementation of quality programmes. The results are descriptions of methodologies, behaviours, values and organization structure used by the organizations to support sustainable health. These are exemplified with practical examples. The methodologies, behaviours, values, and organizational structure are considered possible for other organizations to adopt and all of them are already supported in the quality, management and leadership literature. Support from the health literature is also found for most of the behaviours, methodologies, values, and organizational structure. Surveys and focus groups interviews were carried out in five different organizations in order to find out what is of most importance when practising Quality Management in order to influence sustainable co-worker health. The results pointed to ‘Leadership Commitment’ as the most central of the values for achieving sustainable health among the co-workers. Furthermore, the values ‘Continuous Improvements’, ‘Participation of Everybody’ and ‘Customer Orientation’ were found to be related to sustainable health among the co-workers. The values ‘Leadership Commitment’ and the value ‘Participation of Everybody’ were then further elaborated to find aspects of importance for sustainable co-worker health. From the value ‘Leadership Commitment’ four aspects were extracted. These were labelled ‘Empathy’, ‘Presence and Communication’, ‘Integrity’, and ‘Continuity’. The results showed relations between the value ‘Leadership Commitment’ within Quality Management and sustainable health among the co-workers. Thus it is essential for leaders to work in accordance with that value to achieve results in the work towards sustainable co-worker health. The results indicate that this requires management and leadership that are characterized by the aspects above. The leaders have to: • Really understand the co-workers and their work situation. • Be present and available for co-workers and communicate with them. • Act as a role model, be fair and keep their promises. • Stay in their positions long enough to build up trust and confidence. The value ‘Participation of Everybody’ has also been shown to be related to sustainable health among the co-workers. This indicates that it is important to work in accordance with that value in the struggle to achieve sustainable health among the co-workers. The results imply that this value is characterized by the aspects ‘Development’, ‘Influence’ and ‘Being informed’. This could be done by: • Giving the co-workers opportunities to develop their skills and develop personally. • Letting the co-workers influence their work situation and taking suggestions and proposals from them seriously. • Having good communication within the whole organization. To manage this; the managers have to delegate more and empower the co-workers. These results were then further elaborated within another organization in order to develop a measurement approach that can clarify the extent to which the values, ‘Leadership Commitment’ and ‘Participation of Everybody’ permeate an organization. The developed measurement approach can be used to clarify the extent to which the organization is practising the health-promoting values within Quality Management and in what areas improvement is needed to increase co-worker health. The approach can also help the organization to detect those shortcomings within the management which are important for co-worker well-being. The developed measurement approach can be used to establish and enhance co-worker health by improving their well-being, satisfaction and motivation.
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| 10. |
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| 11. |
- Cvetković, Anita
(författare)
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Kulturmöte i gränslandet mellan motsättningar och möjligheter : Strategier för att tillvarata kulturmötens kreativa potential
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Encounters and relations between people with different cultural backgrounds tend to be primarily discussed in terms of exclusio, prejudice and conflict. This thesis focuses on the creative aspects of intercultural encounters. The starting point is that the parties involved sometimes succeed in avoiding the latent conflicts between cultures by acting trategically. The aim of this thesis is to increase understanding of the possibilities represented by intercultural encounters and to identiy the strategies employed by the actors who try to deal with the contrasts and dilemmas involved in encounters with other peopl with different cultural experiences, identities and methods. The empirical part of the thesis is based on four qualitative case studies that are characterised by rather positive co‐operation between the actors in the intercultural encounter, i.e. "immigrants" and the majority society in Sweden. The empirical data are based on 45 individual interviews, two focus group discussions and a number of minor observations made in the inland part of northern Sweden, where the case studies were carried out. The principal result of this research is that the actors begin to see culture as a possibility when they find themselves in a osition where they feel obliged to change their established patterns of behaviour, due to some sort of crisis situation. The strategies used by the actors to deal with culture conflicts can be divided into intra‐group strategies and inter‐group strategies. The former attempt to achieve relative homogeneity between the competing groups in the field of the intercultural encounter, while the latter illustrate how the participants deal with what they experience as differences. Four inter‐group strategies have been identified: 1) the status quo strategy, 2) the loose coupling strategy, 3) the selective strategy and 4) a culture mixing strategy. The latter three are characterised by innovative combinations that organise the existing cultural elements in a meaningful way These strategies result in new cognitive structures, whose limits maintain the balance between different cultural elements.
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| 12. |
- Danielsson, Ulrika
(författare)
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Relationships between information communication technology and psychosocial life environment : Students and young urban knowledge workers in the ICT-era
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dramatic changes have been taking place in our ways of working and spending leisure time. This relates to the increasing use of ICT (Information Communication Technology) in our lives and is of crucial importance to our future. Today, being physically away from the workplace doesn�t mean that we are necessarily leaving our work tasks behind in psychological terms. The aim of the thesis is to attain a deeper understanding of the relationships between individuals� psychosocial life environment and their use of ICT in order to contribute to the discussion about how everyday use of ICT can affect us. The research is based on two case studies that are presented in research articles. A theoretical framework concerning psychosocial life environment and use of ICT was built upon a review of the literature on environment/role, their relationship to ICT and the boundaries within different roles and environments. The first results in this thesis show that the blurred boundaries between work and leisure begin in school and then continue on into working life. The second result present the different barriers to young women seeking professional roles in the IT-business and the sometimes overlooked fact that every individual has a need to feel needed regardless of whether it is the private or professional role. The third results show that the daily use of ICT creates both needs and activities, but it appears that a sense of lack of control leaves the user feeling negatively stressed. Finally, one example of further research could focus on determining what is the responsibility of the leader of an organization who requires an employee to be reachable any time anywhere?
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| 13. |
- Ding, Xiaosong
(författare)
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Bilinear optimization in computational decision analysis
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In real-life decision analysis, significant recognition has been given to theunrealistic expectation of numerically precise information. Many modernapproaches attempting to handle imprecision have focused more on representationand less on evaluation. The DELTA method, as one of the fewleading approaches, challenges this issue by its evaluation framework thatcan accommodate both precision and imprecision. However, computationally,DELTA and similar approaches may incur time-consuming calculationsdue to the introduction of imprecise information concerning probability andutility. In general, those problems are bounded non-convex bilinear optimizationprograms with disjoint linear constraints, which cannot be solvedeffectively by any existing general-purpose global optimization technique.This thesis presents two enhanced cutting plane algorithms for solvingbounded disjoint bilinear programs arising in computational decision analysis.Each algorithm consists of a local phase designed to determine a localoptimizer from an approximate solution, and a global phase designed to systematicallyexplore the feasible region, subset by subset. These two phasesare switched automatically during the global search procedure. The basicframework builds upon previously developed efficient cutting plane methods.By embedding the lower bounding technique in a branch and bound procedure,the improvement of their performances seems encouraging in the lightof computational experience. Even though the motivation to develop thesealgorithms stems from computational decision analysis, the idea can also beextended to the development of optimization approaches for handling generalbounded disjoint bilinear programs, especially for larger sized ones.
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| 14. |
- Edström, Per
(författare)
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Mathematical modeling and numerical tools for simulation and design of light scattering in paper and print
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work starts with a real industrial problem - the perceived need for a moredetailed and more accurate model for light scattering in paper and print than theKubelka‐Munk model of today. A careful analysis transfers this problem into aphysical description of the phenomena involved. This is then given a mathematicalformulation, and a detailed analysis leads to numerical solution procedures forspecific sub problems. Methods from scientific computing make it possible to meetindustrial demands made on speed and stability, and implementation in computercode is then followed by analysis of accuracy and stability.A problem formulation and a solution method are outlined for the forwardradiative transfer problem. First, all necessary steps to arrive at a numericallystable solution procedure are treated, and then methods are introduced to increasethe speed by a factor of several thousands or millions compared to a naiveapproach. The method is shown to be unconditionally stable, though the problemwas previously considered numerically intractable, and systematic studies ofnumerical performance are presented.The inverse radiative transfer problem is given a least‐squares formulation, anddifferent solution methods are analyzed and compared. Specifically, a two‐phasemethod for estimation of the scattering and absorption coefficients and theasymmetry factor (σs, σa and g) is presented. A sensitivity analysis is given, and it isshown how it can be used for designing measurements with minimal impact frommeasurement noise.It is shown how the standardized use of Kubelka‐Munk and the d/0°instrument leads to errors, and that the errors arising from an over‐idealized viewof the instrument - due to the fact that instrument readings are incorrectlyinterpreted - can be larger than any errors inherent in the Kubelka‐Munk modelitself. It is argued that the measurement device and the simulation model cannot beviewed as separate instances, which is a widespread implicit practice in appliedreflectance measurements. Rather, given a measurement device, measurement datashould be interpreted through a model that takes into consideration the actualgeometry, function and calibration of the instrument.The resulting tool, DORT2002, is in all aspects the Next Generation Kubelka‐Munk, and provides a greater range of applicability, higher accuracy and increasedunderstanding. It offers better interpretation of measurement data, and facilitatesthe exchange of data between the paper and graphical arts industries. It opens forunderstanding of anisotropic reflectance and for the utilization of the asymmetryfactor to design anisotropy, and thereby for the design of different visualappearance or optical performance in new printed or paper products.
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| 15. |
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| 16. |
- Essén, Sofia
(författare)
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Hydroxamate Siderophores and Low Molecular Mass Organic Acids in Terrestrial and Aquatic Environments Determined by Liquid Chromatography Mass Spectrometry
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Siderophores are low molecular mass organic compounds with high iron(III) stability constants. They are produced by many microorganisms, often in combination with low molecular mass organic acids (LMMOAs). Both siderophores and LMMOAs accelerate mineral weathering, thereby enhancing mineral nutrient availability. Siderophore concentrations in natural environments, however, are largely unknown. In the present work, analytical methods based on liquid chromatography (LC) electrospray ionization mass spectrometry (ESI‐MS) were developed and used for concentration determination of selected hydroxamate siderophores and LMMOAs. The use of capillary LC with on‐line pre‐concentration via column switching enabled siderophore quantification with detection limits of 0.1 ‐ 5 nM. Through solid phase extraction even lower detection limits were achieved. In Swedish podzol soil solutions concentrations up to 12 nM ferricrocin and 2 nM ferrichrome were found in the upper soil layes. Additionally, in axenic pine (Pinus sylvestris) seedling cultures, the ectomycorrhizal fungus Hebeloma crustuliniforme was shown to produce ferricrocin as the main siderophore. Moreover, ferricrocin was found in enriched Baltic Sea cyanobacterial populations at concentrations up to 1 nM, while concentrations up to 0.05 nM ferrioxamine B were determined in Baltic Sea surface waters during cyanobacterial blooms. Siderophores have strong affinities for some actinides and may affect radionuclide mobilization in deep subsurface nuclear wase repositories. Two subsurface bacterial strains were shown to produce siderophores under aerobic conditions, i.e. Pseudomonas stutzeri produced mainly ferrioxamine E and Pseudomonas fluorescens produced one pyoverdin siderophore. Siderophores produced by aerobically grown P. stutzeri were not observed either in anaerobic cultures or in deep subsurface water samples.
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| 17. |
- Fahlén, Göran, 1953-
(författare)
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Aspects of the Effort-reward imbalance model of psychosocial stress in the working life
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fahlén, G. (2008). Aspects on the Effort-reward Imbalance model of psychosocial stress in the work environments. Sundsvall, Sweden: Mid Sweden University, Department of Health Sciences. ISBN 978-91-85317-94-3. Since the late 1970s, work related stress has increasingly been recognized as an important determinant for ill-health and disease. One of the most influential stress models is the Effort-Reward Imbalance model (ERI), which stipulates that an imbalance between the perceived effort spent at work and rewards received results in noxious stress. Those with a coping behaviour called Work-related Overcommitment (WOC), including an inability to withdraw from work obligations are especially vulnerable. The model has shown strong explanatory value for a large numbers of harmful health outcomes. The general aim of this thesis was to contribute to the development of the ERI model by exploring the properties of this model in relation to its theoretical assumptions, construct, and application and to improve the knowledge of validity of the ERI-model. The study sample that was used in three papers emanated from the WOLF study (Work, Lipids and Fibrinogen). The analyses were confined to the subset of individuals who answered the ERI questions (n=1174) with complete answers. In one paper, data from the SKA study (Sick leave, Culture and Attitudes) were used and they comprised all employees at the Swedish Social Insurance Agency responsible for management and compensation of illness in the working population (n=5700). All data are based on questionnaires. The results indicate that ERI and WOC are risk factors for sleep disturbances and fatigue. A palpable threshold effect was seen between quartile three and four. Since these symptoms are strongly stress related, our results support the utility of the ERI and WOC scales in assessing stress in working life. Agreement between single questions in the original and an approximate instrument for measuring ERI were low, whereas the agreement between the two ERI scales was reasonable. When approximate instruments are used, questions and scales must be presented thoroughly to facilitate comparisons and the results should be interpreted with caution. Today there are no reasons to use such instruments in the ERI model. One statement in the ERI model is that individuals with the coping behaviour characterised as WOC are particularly vulnerable to an imbalance between perceived effort and reward; i.e., that ERI and WOC interact. No such effect was shown in relation to disturbed sleep and fatigue. There is no convincing evidence that ERI and WOC interact in synergy. Analysis demonstrated that WOC was relatively stable in perceived unchanged conditions as measured by the original, more comprehensive instrument as well as by the present, shortened instrument. Positively or negatively perceived changes in ERI correspond to changes in WOC. This result suggests that WOC, at least in part, may act as not only a coping strategy but also as an outcome from ERI. Taken together, these results concerning WOC, suggest that studies to clarify the role of the WOC dimension are needed. The ERI model states that, when individuals stay in unfavourable conditions characterised as ERI, because there are few alternatives on the labour market or when the individual is at risk of being laid off or of facing downward mobility, they are in a “locked in position” (LIP). A strong association between LIP and ERI was shown, supporting this statement.
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| 18. |
- Feng, Tao
(författare)
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Adaptive finite element methods for parameter estimation problems in partial differential equations
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical and chemical phenomena are often described by a system of partial di®erential equations. These equations usually involve unknown parameters, which cannot be measured directly but which can be adjusted to make the model predictions match the observed data. The process of ¯tting these para- meters to laboratory or plant data is called parameter estimation. In order to recover these parameters, the well-known output least squares formulation is of- ten utilized. To solve the optimization problem governed by partial di®erential equations, the in¯nite-dimensional problem must be approximated by introduc- ing discretizations such as a ¯nite elements or di®erences. It is clear that the e±ciency of the numerical methods dealt with here will be in°uenced by the discretization scheme. The goal of this thesis is to develop e±cient numerical methods for the parameter estimation problems governed by partial di®erential equations, based on adaptive ¯nite element methods. This work was initiated by an investigation into an a posteriori error esti- mator of residual type for parameter estimation problems with a ¯nite number of unknown parameters. It appears that an adaptive ¯nite element algorithm guided by the derived a posteriori error estimator produces a sequence of eco- nomical, locally re¯ned meshes. The methods are then applied to the identi¯ca- tion of elastic constants in paper from measured displacements. Further, some a posteriori error estimators of gradient recovery type are derived for the error in parameters due to the discretization. The main advantages of using error estimators of this type are the simplicity of their implementation and their cost e®ectiveness. Often, the unknown parameters are functions, which also need to be dis- cretized. Adaptive ¯nite element method is developed for the estimation of distributed parameters in elliptic equations with multi-mesh techniques. Finally, a goal-oriented adaptive method, dual weighted residual methods (DWR methods) are employed determining the elastic constants in paper from measured displacements.
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| 19. |
- Fjellström, Helena
(författare)
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Inhibition of light-induced colour reversion of wood-containing papers by means of coating
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main purpose of this thesis was to find ways to maintain a low level of light‐induceddiscolouration at an increased addition of mechanical and chemimechanical pulps in coated highqualityfine paper and magazine paper grades. Current technology allows the production of highyieldpulps such as thermomechanical and chemimechanical pulps with properties suitable formanufacturing high‐quality paper or paperboard with a low basis weight. Coating of woodcontainingpaper will probably be necessary for photo‐stability reasons if lignin‐containing pulps areto be used as the main fibre furnish in long‐life and high‐value products.In order to find the most suitable pulp for this purpose, light‐induced discolouration of a variety ofpaper samples from unbleached and bleached softwood and hardwood pulps was studied under bothaccelerated and long‐term ambient light‐induced ageing conditions. Hardwood high‐yield pulps,especially aspen pulps, were proven to be more photo‐stable compared to softwood pulps. Hardwoodpulps should therefore be the first choice for applications where a high permanence is desirable.Evaluating ageing characteristics using the CIELAB colour system showed that accelerated ageingconditions tend to mainly increase the b* value and decrease the L* value (i.e. yellow the pulp),whereas long‐term ambient ageing also increases the a* value, which makes the pulp more reddish.A new method for studying the influence of the UV‐screening properties of coating layers on abase paper was developed, and used to investigate the effect of pigment, pigment size distribution,binder and UV‐absorbing additives. The coat weight and pigment type were found to be the mostimportant factors for reducing the transmittance of UV‐radiation. Coating colours containing kaolinpigments had a lower UV‐transmittance than calcium carbonate pigments. Of the calcium carbonates,precipitated calcium carbonates were better than ground calcium carbonates and the difference wasgreater at higher coat weights. The particle size distribution should preferable be narrow. When thebest pigment (bleached kaolin) and the best binder (styrene butadiene latex) were combined withtitanium dioxide, the UV‐transmittance could be reduced by about 90% at a coat weight of ~10 g/m2.At a coat weight close to 20 g/m2, the transmittance was close to zero. This shows that it is possible tomore or less fully protect a double coated base paper from harmful UV‐radiation, when the coatinglayer has an optimum composition for that purpose. A prerequisite to reach so far is that the coatinglayer has an even coat weight.
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| 20. |
- Flodén, Liselott, 1967-
(författare)
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G-Convergence and Homogenization of some Sequences of Monotone Differential Operators
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis mainly deals with questions concerning the convergence of some sequences of elliptic and parabolic linear and non-linear operators by means of G-convergence and homogenization. In particular, we study operators with oscillations in several spatial and temporal scales. Our main tools are multiscale techniques, developed from the method of two-scale convergence and adapted to the problems studied. For certain classes of parabolic equations we distinguish different cases of homogenization for different relations between the frequencies of oscillations in space and time by means of different sets of local problems. The features and fundamental character of two-scale convergence are discussed and some of its key properties are investigated. Moreover, results are presented concerning cases when the G-limit can be identified for some linear elliptic and parabolic problems where no periodicity assumptions are made.
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| 21. |
- Gidlund, Mikael
(författare)
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Design and Performance of Packet Retransmission Diversity Scheme for Wireless Networks
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High data-rate wireless access systems are currently under discussion since the demand for wireless multimedia communication is rapidly increasing due to strong advances in wireless Internet services. Reliable high-speed data communications is one of the major challenges with regards to harsh conditions. With the necessity for high data rates, linear multi-level modulation schemes are becoming more and more important in wireless communication systems since they are bandwidth efficient. In this thesis protocols are designed and evaluated which improve system performance by combining ARQ-induced retransmissions through multipath channels in order to reduce the latency and improve the system throughput. The starting point is to show that the employment of simple packet combining schemes to wireless LANs such as IEEE 802.11, can achieve a considerable performance gain with the addition of only a small increase in complexity. A low-complexity method for enhancing and exploiting retransmission diversity by varying the bit-to-symbol mapping for each retransmission of a packet is evaluated. The selected mappings are chosen in order to maximize a bit log likelihood ratio (LLR) based metric. An ARQ scheme is also proposed, which combines retransmissions and bandwidth efficient multi-level modulation techniques with a change in the symbol mapping for every retransmission. The main idea behind this proposal is to take advantage of the extra dimension provided by a retransmission diversity scheme in improving the power efficiency if the used modulation without altering the diversity order of the system. Considering the overall scheme as one entity it is possible to obtain a transmission scheme able to perform very well in both additive Gaussian and fading channels without increase in receiver complexity. Finally, multiple antenna systems with ARQ functionality are evaluated. It has been established that using multiple antennas at both the transmitter and receiver along with intelligent signal design enables us to achieve better reliability as well as increase the transmission rate. In this thesis a space-time block coded hybrid ARQ scheme is considered which exploits both the spatial and time diversity of the MIMO channel. A bit-to-symbol mapping ARQ scheme suitable for multiple antenna systems is also considered.
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| 22. |
- Giritli Nygren, Katarina, 1971-
(författare)
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"e" i retorik och praktik. : Elektronisk förvaltning i översättning.
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall purpose of this study is to contribute to the discussion of eGovernment implementation by making the implicit organisational micro dynamic processes involved in the framing and implementation of eGovernment explicit. I want to highlight the important process trough which eGovernment is framed and translated by organisational members and in what way it effects different divisions of practice. To do so, two different analytical aspects of organisational life, the rhetoric of management and the reality of work practices are used as a theoretical context for analysing some implications of eGovernment implementation. These analytical dimensions of organisational life are used to discuss a case study looking at the implementation of eGovernment in a local Swedish municipality. The main contribution of this thesis is a theorisation of how to understand the organisational micro dynamic processes involved in the implementation of eGovernment in public administration. New insights could be gained, for researchers and practioners, by analysing the transformation of practice as an ongoing process characterised by micro-political translation processes involving actors as well as actions and meanings in both rhetoric and practice.
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| 23. |
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| 24. |
- Hallin, Karin
(författare)
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Att vara sjuksköterska : En studie av sjuksköterskeprofessionen avseende omvårdnad, handledning och utveckling
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Avhandlingens övergripande syfte var att klarlägga sjuksköterskors erfarenheter av sjuksköterskeprofessionen avseende omvårdnad, handledning och utveckling. Avhand‐lingen innefattar två kvalitativa (I, II) och två kvantitativa (III, IV) studier. Femton sjuksköterskor intervjuades sex år efter examen (I, II). Sjuksköterskorna var bland de första i Sverige med treårig sjuksköterskeutbildning. Handledare till sjuksköterske‐studenter i verksamhetsförlagd utbildning besvarade ett frågeformulär om handledning före/efter införd handledningsmodell (III, IV). I handledningsstudierna deltog 113 sjuksköterskor år 2000 (III) och 109 (III) respektive 142 (IV) sjuksköterskor år 2006. Svarsfrekvensen motsvarade ca 71% (III, IV). Innehållsanalys (I, II) och statistiska beräk‐ningar (III, IV) utfördes. Analysen visade att sjuksköterskor med treårig sjuksköterskeutbildning och sex års erfarenhet hade hittat sin nisch (II). Ingen ångrade sitt yrkesval. Många var under‐stimulerade samtidigt som de balanserade mellan påfrestning och stimulans (I) hinder och möjligheter (II). Flertalet var tveksamma till om de skulle orka arbeta fram till pensionsåldern (I, II). Inrättandet av en handledningsmodell som gav stöd till både sjuksköterskestudenter och handledare visade sig vara ett bra sätt i att organisera samverkan mellan handledare och lärare (III). Flertalet handledare var nöjda med det stöd de fått och upplevde säkerhet i handledarrollen (III). Emellertid, sjuksköterskor med och utan specialistutbildning värderade sjuksköterskestudenter olika (IV). Behovet av ett fokuserat lärande visades som ett mönster genom resultaten (I, II, III, IV). Avhandlingen visar genom resultaten att sjuksköterskor verkar i en komplex pro‐fession där det krävs skickliga sjuksköterskor för att klara det arbete sjuksköterskan är satt att sköta. För framgång i omvårdnad, handledning och utveckling är den lärande miljön central. En miljö där teori, praktik, forskning och reflektion vävs samman och där stöd, samverkan och professionell utveckling är ledstjärnor. Avhandlingen visar att en ökad samverkan mellan vårdverksamhet och universitet/högskola är nödvändig för att sjuksköterskeutbildningen och omvårdnadsarbetet skall kunna anpassas till hälso‐ och sjukvårdens ökade krav. Avhandlingens resultat kan användas som grund för fortsatta diskussioner med hänsyn till omvårdnadsvetenskap och beslut kring sjuksköterskans arbete såväl i utbildningssammanhang som i vårdverksamhet.
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| 25. |
- Hummelgård, Magnus, 1978-
(författare)
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In-situ TEM Probing of Nanomaterials
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanomaterials because of their small size, may have special properties unlikely to be seen in ordinary types of materials. Nanomaterials like nanotubes,nanowires and nanoparticles are best studied at the nanoscale, vital but also problematic. In this thesis we use a transmission electron microscope (TEM)combined with a scanning tunneling microscope probe. This system allows TEM images to be captured and recorded into a movie together with recordedelectrical data for real time analysis. Using this method we found that the electrical conductivity of molybdenumbased nanowires Mo6S3I6 can be improved by current induced transformation. This might be a general method of improving nanowires which is of high valueif the wires are to be used in electrical circuits or field emission devices. The bending modulus for these nanowires were also determined, by an electromechanical resonance method, to 4.9 GPa. The sintering phase of silver nanoparticles, used in electrical conductive ink for printing electrical circuits, were studied by the in-situ TEM probing method. We observed that percolation path ways are formed and that the dispersive agent of the particles can be pyrolysed into a net of carbon with characteristics similar to graphite. We also developed a method for decorating nanowires and nanotubes with gold nanoparticles. Nanowire particle composites are often used in assembling more complex devices (electronic circuits) or for linking to organic molecules (biosensor applications) and existing particle decoration methods are either difficult or with low yield. By in situ TEM probing we found that carbon nanocages can be grown onto these gold nanoparticles. The size of the gold nanoparticles is controllable an thus the size of the nanocages. These nanocages may be used in medicine- or hydrogen storage-applications.
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