| 1. |
- Danielsson, Tatiana
(author)
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Further Investigations of Convergence Results for Homogenization Problems with Various Combinations of Scales
- 2020
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Doctoral thesis (other academic/artistic)abstract
- This thesis is based on six papers. We study the homogenization of selected parabolic problems with one or more microscopic scales in space and time, respectively. The approaches are prepared by means of certain methods, like two-scale convergence, multiscale convergence and also the evolution setting of multiscale convergence and very weak multiscale convergence. Paper I treats a linear parabolic homogenization problem with rapid spatial and temporal oscillations in perforated domains. Suitable results of two-scale convergence type are established. Paper II deals with further development of compactness results which can be used in the homogenization procedure engaging a certain limit condition. The homogenization procedure deals with a parabolic problem with a certain matching between a fast spatial and a fast temporal scale and a coefficient passing to zero that the time derivative is multiplied with. Papers III and IV are further generalizations of Paper II and investigate homogenization problems with different types of matching between the microscopic scales. Papers III and IV deal with one and two rapid scales in both space and time respectively. Paper V treats the nonlinearity of monotone parabolic problems with an arbitrary number of spatial and temporal scales by applying the perturbed test functions method together with multiscale convergence and very weak multiscale convergence adapted to the evolution setting. In Paper VI we discuss the relation between two-scale convergence and the unfolding method and potential extensions of existing results. The papers above are summarized in Chapter 4. Chapter 1 gives a brief introduction to the topic and Chapters 2 and 3 are surveys over some important previous results.
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| 2. |
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| 3. |
- Olsson, Karl Wilhelm, 1985-
(author)
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Persistent ductus arteriosus in extremely preterm infants
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Patent ductus arteriosus (PDA) is common in infants born <28 weeks gestational age (GA) and associated with significant morbidity. Despite extensive research efforts, the indications for PDA treatment remain controversial. The aims of these studies were to gain knowledge of factors affecting ductal closure during the early postnatal period and provide better means for identification of preterm infants that may benefit from PDA treatment.In Paper I, infants born <28 weeks GA and pharmacologically treated for PDA were retrospectively identified and their echocardiographic examinations were reviewed. Twenty-nine (52%) infants successfully closed and 27 (48%) infants failed to close PDA during treatment. High maximal ductal flow velocity (Vmax) was independently associated with closure (OR 3.04, p=0.049).Paper II prospectively included infants born <28 weeks GA and assessed early respiratory, circulatory and echocardiographic parameters. PDA was persistent in 18 (30%) and ultimately closed or insignificant in 42 (70%) infants. Echocardiographic criteria for hemodynamically significant PDA on days 2-7 did not predict persistent PDA (p=1.000). Mechanical ventilation (p=0.025), high mean airway pressure (p=0.020) and low Vmax (p=0.024) during day two were associated with future persistent PDA.Blood samples were obtained during the second day of life from 47 of the infants in Paper II and serum markers previously associated with PDA or factors affecting PDA were analyzed for Paper III. Inflammatory markers and erythropoietin (EPO) were elevated in infants with future persistent PDA. EPO levels were also higher in infants that did not close PDA during pharmacological treatment.In Paper IV, 44 infants born <28 weeks GA with surgically ligated PDA were retrospectively compared to non-surgically treated controls. Ligated infants had larger ductal diameter prior to, and lack of diameter decrease after pharmacological treatment for PDA (p=0.048 and p=0.022 respectively), and higher incidence of severe bronchopulmonary dysplasia (p=0.025). Longer periods with invasive ventilation was independently associated with ligation (OR 1.04, p=0.018).In conclusion, early hsPDA do not predict persistence of ductus arteriosus in extremely preterm infants, but Vmax and EPO are promising early markers for prediction of persistence and should be subjects of future studies.
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| 4. |
- Pembe, Andrea Barnabas, 1966-
(author)
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Quality Assessment and Monitoring of Maternal Referrals in Rural Tanzania
- 2010
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Doctoral thesis (other academic/artistic)abstract
- An efficient referral system is essential in providing access to emergency obstetric care at higher levels of care by supporting antenatal and delivery services in the primary level of care facilities (PLCF). The aim of this thesis was to assess community and health service factors affecting the quality of maternal referrals in rural Tanzania. Ten focus group discussions (FGDs) with health workers and community members were conducted to describe their perceptions on maternal referrals. Women (n=1118) were interviewed to determine awareness of obstetric danger signs and associated factors. Compliance with referral advice was analysed for 1538 women referred from PLCF. Counselling on danger signs and adherence to referral criteria was observed in 438 antenatal consultations. FGDs indicated that women had limited influence, especially on emergency referrals. The process of deciding to seek referral care considered the perception of seriousness and past experience of referral, access to transport, and the cost involved. Women had low awareness of danger signs of obstetric complications: higher years of schooling increased the likelihood of being aware of danger signs. Demographic risks accounted for 70% of referred women but less than half complied with the advice. Compliance was higher for historical obstetric risks, prenatal, natal, and postnatal complications groups. Few women were counselled on pregnancy danger signs and a significant number with ≥5 pregnancies and primigravidae <20 years were not informed of the risk factors. This thesis demonstrated a need for reviewing referral guidelines and an increase in supportive supervision for health workers counselling on obstetric danger signs to enhance acceptance of referrals advices. Women’s education should be given priority for increasing participation in decisions and becoming more aware of danger signs. Costs involved in maternal referrals can be relieved by improving family income, infrastructure, and alleviating the cost of referral through mobilising community transport and financial schemes.
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| 5. |
- Vessby, Johan, 1976-
(author)
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Analysis of shear walls for multi-storey timber buildings
- 2011
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Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis addresses questions of how wind loads acting on multistoreytimber buildings can be dealt with by structural design of such buildings.The conventional use of sheathing either nailed or screwed to a timberframework is considered, together with other stabilizing structures such ascross-laminated timber panels.The finite element method was employed in simulating the structuralbehaviour of stabilizing wall units. A series of studies was carried out of walls inwhich the sheathing was nailed to a timber frame. Different structural levelswere studied starting with modelling the performance of single sheathing-toframingconnections, to the use of models for studying the overall structuralbehaviour of walls. The results of calculations using models for simulation ofwalls subjected to different loading agree reasonably well with experimentalresults. The structural properties of the connections between the sheathing andthe frame, as well as of the connections between the members of the frame,were shown to have a substantial effect on the simulated behaviour of shearwall units. Both these types of connections were studied and described inappended papers.Regarding cross-laminated timber wall panels, it was concluded that walls witha high level of both stiffness and strength can be produced by the use of suchpanels, and also that the connections between the solid wall panels can bedesigned in such a way that the shear forces involved are transmitted from onepanel to the next in an efficient manner.Other topics in the thesis include the properties of connections between shearwalls and the rest of the building. Typically high tension forces occur at specificpoints in a timber structure. These forces need to be transmitted downwards inthe structure, ultimately connecting them to the substrate. A lap-joint that maybe used for this purpose has been studied using generalized Volkersen theory.Finally the maximum capacity of a conventional rail to substrate connection hasbeen examined using linear and nonlinear fracture mechanics.
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| 6. |
- Abbadi, Ahmad, et al.
(author)
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Validation of the Health Assessment Tool (HAT) based on four aging cohorts from the Swedish National study on Aging and Care
- 2024
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In: BMC Medicine. - : BioMed Central (BMC). - 1741-7015. ; 22:1
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Journal article (peer-reviewed)abstract
- Background: As global aging accelerates, routinely assessing the functional status and morbidity burden of older patients becomes paramount. The aim of this study is to assess the validity of the comprehensive clinical and functional Health Assessment Tool (HAT) based on four cohorts of older adults (60 + years) from the Swedish National study on Aging and Care (SNAC) spanning urban, suburban, and rural areas.Methods: The HAT integrates five health indicators (gait speed, global cognition, number of chronic diseases, and basic and instrumental activities of daily living), providing an individual-level score between 0 and 10. The tool was constructed using nominal response models, first separately for each cohort and then in a harmonized dataset. Outcomes included all-cause mortality over a maximum follow-up of 16 years and unplanned hospital admissions over a maximum of 3 years of follow-up. The predictive capacity was assessed through the area under the curve (AUC) using logistic regressions. For time to death, Cox regressions were performed, and Harrell’s C-indices were reported. Results from the four cohorts were pooled using individual participant data meta-analysis and compared with those from the harmonized dataset.Results: The HAT demonstrated high predictive capacity across all cohorts as well as in the harmonized dataset. In the harmonized dataset, the AUC was 0.84 (95% CI 0.81–0.87) for 1-year mortality, 0.81 (95% CI 0.80–0.83) for 3-year mortality, 0.80 (95% CI 0.79–0.82) for 5-year mortality, 0.69 (95% CI 0.67–0.70) for 1-year unplanned admissions, and 0.69 (95% CI 0.68–0.70) for 3-year unplanned admissions. The Harrell’s C for time-to-death throughout 16 years of follow-up was 0.75 (95% CI 0.74–0.75).Conclusions: The HAT is a highly predictive, clinically intuitive, and externally valid instrument with potential for better addressing older adults’ health needs and optimizing risk stratification at the population level. © The Author(s) 2024.
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| 7. |
- Jungstrand, Anna, 1976-
(author)
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Det litterära med reportaget : Om litteraritet som journalistisk strategi och etik
- 2013
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Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis explores the literarity of reportage, with a focus on the 20th century and modern reportage. The aim is to describe the literary strategies used in modern text-based reportage and how these strategies relate to journalistic standards of credibility and ethics. A primary focus is the question of what the reportage is looking for in the literary, what happens to this literarity when it is used for journalistic purposes, and, in turn, how the literary establishes ethics in the text. By suggesting that a piece of reportage is a journalistic text that simultaneously tells the story about the reporter’s encounter with the event, this dissertation sheds light on possible approaches to the concept of literarity: Subjectivity, narrativity, meta-narrative aspects, the poetic function of language and the performative movements in the text. The ethics of reportage is also to be derived from the encounter, and this thesis implements a concept of ethics in conversations with Emmanuel Levinas and dialogical philosophy. It provides an opportunity to separate ethics from moral, ideological and political dimensions of responsibility in the encounter. This aspect of ethics, where literarity and counter-movement operate beyond the direct intention, is what is needed to understand the reportage genre. The dissertation also includes six longer reportage analyses embodying its results: Djuna Barnes’s, Vagaries Malicieux, Ryszard Kapuściński’s Another Day of Life, Truman Capote’s In Cold Blood, Hanna Krall’s A Tale for Hollywood, Sven Lindqvist’s Kina nu: Vad skulle Mao ha sagt? and Joan Didion’s, Slouching towards Bethlehem.
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| 8. |
- Jörngården, Anna, 1978-
(author)
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Tidens tröskel : Uppbrott och nostalgi i skandinavisk litteratur kring sekelskiftet 1900
- 2012
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Doctoral thesis (other academic/artistic)abstract
- This study illuminates Scandinavian literature’s engagement with the fin de siècle as a momentous temporal threshold, when the widespread feeling of being poised on the brink of a distinctly modern age while at the same time witnessing the demise of the old world produced excitement as well as anxiety, a sense of loss and nostalgia. The dissertation explores how three male authors of the Scandinavian canon – Ola Hansson, August Strindberg and Knut Hamsun – depict the ambivalent experience of being torn between nostalgia and a heady sense of departure. All three authors spent time on extended journeys abroad or went into self-imposed exile. The study shows how the experiences of travel and dislocation play a crucial part in their involvement with the sense of transition in time, and how the journey functions as a figure of loss as well as of liberation.By focusing on male authors and their male literary characters, this dissertation exposes how becoming “modern,” a process that entails the experience of change and loss, comes to be framed as a uniquely male privilege. In the same vein, it highlights how fin-de-siècle nostalgia functions as a masculine structure of emotion. The study thus sheds light on dominant practices of interweaving notions of gender and time that still today influence how we perceive masculinity and femininity in relation to the past and the present. This study also shows how nostalgia’s search for authenticity – in addition to having problematic implications for conceptions of gender identity – can both inform and be appropriated by other reactionary and ideologically questionable movements.Importantly also, this dissertation argues that the three authors’ fin de-siècle expressions reveal the potential for nostalgia to play a positive role, as a creative, productive and even radical force. Serving as an impetus to critique the values associated with progress as well as the link between masculinity and modernity, nostalgia opens up the potential for grief, regret and longing to become subversive. In all the three authorships, nostalgic yearning fosters an impulse to search for new forms of literary expression – forms that bring each author towards modernism. In sum, the readings bring to light new perspectives on how Scandinavian fin-de-siècle literature that centred on the feelings of loss, nostalgia and the dislocation of identity and experience prefigured the key concerns of 20th century modernity and modernist literature
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| 9. |
- Oscarsson, Jan, 1958-
(author)
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Strength grading of structural timber and EWP laminations of Norway spruce : Development potentials and industrial applications
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Machine strength grading of structural timber is a sawmill process by which considerable value is added to sawn products. The principle of such grading is that the strength of a timber member is predicted on the basis of a so called indicating property (IP) which, in general, represents an averaged value of the modulus of elasticity (MOE) measured over a board length of about one meter or more.A limitation of today’s grading methods is that the accuracy of strength predictions is often rather poor, which results in a low degree of utilization as regards structural potential of sawn timber. However, it has for many years been well known to researchers that much better strength predictions can be made by using localized MOE values, determined over a very short length, as IP. Still, the determination of such values in a sawmill production environment has been technically very difficult to achieve.In the research presented in this thesis, dot laser scanning with high resolution was utilized for detection of local fibre orientation on the surfaces of timber members. Since wood is an orthotropic material with superior structural performance in the longitudinal fibre direction, information about fibre orientation was, in combination with beam theory and measured wood material properties, used to determine the bending MOE variation along boards. By application of an IP defined as the lowest MOE found along a board, more accurate strength predictions than what is obtained by common commercial grading techniques was attained.The thesis also involves flatwise wet gluing of Norway spruce side boards into laminated beams. As side boards, being cut from the outer parts of a log, have excellent structural properties it was not surprising to find that the beams had high strength and stiffness, even when laminations of sawfalling quality were used. The possibility of grading boards in a wet state by means of axial dynamic excitation was investigated with a positive result and application of simple grading rules resulted in considerable improvement of beam bending strength. Finally, bending MOE variation determined on the basis of laser scanned fibre directions was used for identification of weak sections in laminations. Elimination of such sections by means of finger jointing showed that average lamination strength of a board sample could be improved by more than 35 percent.
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| 10. |
- Ranjbar, Vahid
(author)
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Challenges for ERTMS related to implementation, technology and railway capacity
- 2021
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Licentiate thesis (other academic/artistic)abstract
- The main purpose of European Rail Traffic Management System (ERTMS) is to remove crossborder barriers and create an interoperable railway network across European countries (Smithet al. 2012). Since its birth, ERTMS has faced several issues regarding interoperability andimplementation. In addition, one of the main questions for decision-makers and infrastructuremanagers regarding ERTMS is determining what level of operation is suitable to implementand deliver additional performance compared to legacy systems.This thesis aims to identify challenges for the ERTMS related to implementation, andinteroperability to achieve a mobile and intelligent railway transport system. A subsequentstudy on railway capacity is performed. It investigates the impact of ERTMS Hybrid Level 3(HL3) compared to the European Train Control System Level 2, (ETCS L2) and a Swedishlegacy system, ATC2. To achieve the goals of this study, two methodologies are used: 1)Literature review and 2) Simulation.The literature reviews were conducted in order to determine what the challenges ofimplementation of ERTMS are to resolve issues related to ERTMS subsystems (Global Systemfor Mobile Communication – Railway (GSM-R), and ETCS). ETCS needs to exploit hybridtechnologies for gradual deployment of next generation signalling systems. GSM-R must bereplaced with new technologies such as, long-term evolution (LTE) to support necessary datatransmission capacity for implementation of the next generation of signalling system.Furthermore, the literature review regarding achieving interoperable and intelligent railwaytransport shows that reducing wayside equipment have potential to provide a more costefficientrailway transport. To test and validate this finding, it is necessary to develop adaptedtools for railway and signalling systems. Providing flexible railway operation with backwardforwardinteroperability and hybrid solutions will make it possible to gradually upgrade currentsystems.As decision-makers look for additional performance in new signalling systems over legacyinstallations, the impact various signalling systems have on line capacity must be examined.To this end, a comparative analysis between legacy ATC, ETCS Level 2, and ETCS HybridLevel 3 using simulation tool was performed. The case study was performed on a highfrequency traffic commuter train line in Stockholm during peak hours. The results of study showHL3 delivers better performance compared to the legacy system and ETCS L2, and can deliveracceptable performance for a commuter train line with high density. Considering the casestudy, it can be concluded that HL3 delivers better performance on commuter train lines withhigh density.
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