| 1. |
- Anton, Rikard, 1989-
(författare)
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Exponential integrators for stochastic partial differential equations
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stochastic partial differential equations (SPDEs) have during the past decades become an important tool for modeling systems which are influenced by randomness. Because of the complex nature of SPDEs, knowledge of efficient numerical methods with good convergence and geometric properties is of considerable importance. Due to this, numerical analysis of SPDEs has become an important and active research field.The thesis consists of four papers, all dealing with time integration of different SPDEs using exponential integrators. We analyse exponential integrators for the stochastic wave equation, the stochastic heat equation, and the stochastic Schrödinger equation. Our primary focus is to study strong order of convergence of temporal approximations. However, occasionally, we also analyse space approximations such as finite element and finite difference approximations. In addition to this, for some SPDEs, we consider conservation properties of numerical discretizations.As seen in this thesis, exponential integrators for SPDEs have many benefits over more traditional integrators such as Euler-Maruyama schemes or the Crank-Nicolson-Maruyama scheme. They are explicit and therefore very easy to implement and use in practice. Also, they are excellent at handling stiff problems, which naturally arise from spatial discretizations of SPDEs. While many explicit integrators suffer step size restrictions due to stability issues, exponential integrators do not in general.In Paper 1 we consider a full discretization of the stochastic wave equation driven by multiplicative noise. We use a finite element method for the spatial discretization, and for the temporal discretization we use a stochastic trigonometric method. In the first part of the paper, we prove mean-square convergence of the full approximation. In the second part, we study the behavior of the total energy, or Hamiltonian, of the wave equation. It is well known that for deterministic (Hamiltonian) wave equations, the total energy remains constant in time. We prove that for stochastic wave equations with additive noise, the expected energy of the exact solution grows linearly with time. We also prove that the numerical approximation produces a small error in this linear drift.In the second paper, we study an exponential integrator applied to the time discretization of the stochastic Schrödinger equation with a multiplicative potential. We prove strong convergence order 1 and 1/2 for additive and multiplicative noise, respectively. The deterministic linear Schrödinger equation has several conserved quantities, including the energy, the mass, and the momentum. We first show that for Schrödinger equations driven by additive noise, the expected values of these quantities grow linearly with time. The exponential integrator is shown to preserve these linear drifts for all time in the case of a stochastic Schrödinger equation without potential. For the equation with a multiplicative potential, we obtain a small error in these linear drifts.The third paper is devoted to studying a full approximation of the one-dimensional stochastic heat equation. For the spatial discretization we use a finite difference method and an exponential integrator is used for the temporal approximation. We prove mean-square convergence and almost sure convergence of the approximation when the coefficients of the problem are assumed to be Lipschitz continuous. For non-Lipschitz coefficients, we prove convergence in probability.In Paper 4 we revisit the stochastic Schrödinger equation. We consider this SPDE with a power-law nonlinearity. This nonlinearity is not globally Lipschitz continuous and the exact solution is not assumed to remain bounded for all times. These difficulties are handled by considering a truncated version of the equation and by working with stopping times and random time intervals. We prove almost sure convergence and convergence in probability for the exponential integrator as well as convergence orders of ½ − ?, for all ? > 0, and 1/2, respectively.
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| 2. |
- Bodin, Ingrid, 1944-
(författare)
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Impairment of intra-oral sensation, discrimination ability, and swallowing function following radiotherapy and surgery for oral and pharyngeal cancer
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oral and pharyngeal cancer is commonly treated with a combination of radiotherapy and surgery. It is a clinical knowledge that patients often experience severe swallowing disorders following treatment. Since surgical sequelae are instantaneous and obvious, little attention has been paid to other concurrent effects of the treatment. To shed light on this subject, the aim of this thesis was twofold (i) to make a retrospective inventory of the sequelae following treatment and (ii) to perform a prospective, inceptive examination at diagnosis, and to follow-up after radiotherapy, six months and 12 months after surgery. The files of ninety-nine patients revealed that following treatment one-third had to use gastric fistulas and more than nine of ten patients had restricted swallowing capacity. Every second patient could only swallow puréed or liquid food. Adequate intra-oral sensation and discrimination ability is essential for bolus preparation and bolus control, for appropriate elicitation of the swallowing reflex and, hence, for the oral phase of swallowing. At the inceptive examination, the prospective part of the study demonstrated intra-oral discrimination ability in patients was equal to that in healthy controls but was impaired six months after treatment and there was no significant improvement after 12 months. It had been expected that the patient’s healthy, non-tumor side would compensate but it did not. An explanation was found when it was revealed that radiotherapy induced a delayed decline in intra-oral sensation. Sensory decline was not demonstrated within a month after radiotherapy but was manifest six months later. Since the radiotherapy field includes the neck, because of the risk for metastasis, it is highly plausible that pharyngeal sensation declines in a manner corresponding to that found intra-orally when the healthy side is irradiated. In accord with this presumption, pharyngeal swallowing function deteriorated in patents with oral tumors. Cineradiographic evaluation of oral and pharyngeal swallowing function disclosed a significant association between the degree of swallowing dysfunction and the degree of sensory decline and with the degree of impairment of shape recognition. Conclusions: Delayed intra-oral sensory decline, found to be induced by radiotherapy, can be expected to appear in the entire radiation field, including the oral cavity and the pharynx, with adverse effect on swallowing. Testing intra-oral sensation close to the last radiotherapy session is not advisable, because sensory decline does not develop immediately after radiotherapy but manifests after six months. Spontaneous sensory rehabilitation cannot be expected after six months. The significant association between degree of swallowing dysfunction and degree of intra-oral sensory decline and impaired discrimination ability must be considered in the quest for functional rehabilitation of patients treated for oral or pharyngeal cancer.
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| 3. |
- Hasselblad, Annika, 1991-
(författare)
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Unraveling the Socio-Technical Tensions of Performance Measurement in Public Welfare Organizations
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the name of efficiency, performance measurement has gained traction in public welfare organizations. The idea of performance measurement originates from views of all organizations rooted in scientific management notions that emerged during industrialization, as kinds of production units, according to an industrial logic. However, the primary objectives of public welfare organizations are to meet situational needs of individuals. Thus, applying performance measurement in public welfare organizations has resulted in tensions between social and scientific perspectives that have led to devaluation of welfare professionals’ reasoning and judgement in relation to performance measures. The purpose of the thesis is to unravel the sociotechnical tensions between performance measurement and public welfare practice by addressing the underlying logics in theory and praxis. In addition, the knowledge acquired from theory and praxis used to reflect on a practical case of performance measurement design, to advance the design of performance measurements in public welfare organizations and avoid dysfunctional effects. All six papers have contributed to elucidation of important aspects of the socio-technical tensions. First, they have provided theoretical insights regarding underlying logics and values (Paper I), and constructive and deconstructive approaches (Paper II) in public performance measurement research. Second, they have provided practical lessons showing how industrial values have obtained precedence in design, decision-making and management, as well as in the choice of data. In this sense, although they are based on a welfare logic, public welfare organizations are haunted by the ghost of industrialization, which has fueled anxiety among welfare workers, with dysfunctional consequences, as they have had to adjust to a measurement regime that does not sufficiently value their reasoning and judgement. Thus, welfare logic needs to be integrated into definitions of performance and its measurement. Third, they have informed reflections on the design of performance measurements from an empirical case study. Together with the theoretical insights and practical lessons, the reflections reveal in detail how a welfare logic can be easily subordinated in the construction of performance measurement as welfare workers are often only involved in the use stage. In summary, this thesis makes a multi-level contribution to unraveling the socio-technical tensions of performance measurement in public welfare organizations, which I hope will be useful for public welfare performance measurement researchers, measurement practitioners, welfare professionals, and managers.
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| 4. |
- Karlsson, Ann-Christin, 1960-
(författare)
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Att vara vaken under operation i regional anestesi : Från patienters upplevelser till en vårdande modell
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aim: The overall aim of the thesis was to describe the experiences of awake patients during surgery under regional anesthesia. In addition, the aim was to develop a model for intraoperative care that can support and enhance patients’ well-being during the intraoperative period. Methods: Study I was a patient interview study guided by a reflective lifeworld approach. In study II a philosophical reflection of the findings from study I was carried out. In study III a hermeneutic approach inspired by Ricoeur and Gadamer was used in order to interpret video recorded material. In study IV a hermeneutic approach inspired by Gadamer was used to synthesize the findings in studies I-III transformed into an intraoperative caring model. Overall main findings: The analysis shows that being awake during surgery can be compared with walking a tightrope because of ambiguous feelings. The proximity and presence of the nurse anesthetist (NA) anchors the patient in the present and strengthens the patient’s feeling of trust. The temporary disruption in the relationship between the body and the world due to regional anesthesia means that the patient’s being in the world is exposed to revolutionary experiences. Gaps between the patient’s experiences and the situation can be bridged over when the NA acts as the patient’s bodily extension and links the patient as a subject to the world in the intraoperative situation. From the patient’s perspective this calls for the NA’s proximity and genuine presence in the ‘intraoperative caring space’. When the NA’s performance of his/her professional duties clashes with the patient’s existential being in the intraoperative situation the need of present presence from the NA is crucial.Conclusions: The findings contribute to knowledge development about intraoperative care and raise awareness that care for the awake patient cannot be performed on formal routines that might disregard the uniqueness of each patient’s situation. The model can be used as a tool to encounter awake patients’ existential needs in the intraoperative situation and to further enlighten NAs about the possible impact of their proximity, interaction and communication behavior in the delivery of intraoperative nursing care.
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| 5. |
- Kåhlin, Ida, 1977-
(författare)
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Delaktig (även) på äldre dar : Åldrande och delaktighet bland personer med intellektuell funktionsnedsättning som bor i gruppbostad
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Participation of people in all ages is one of the main goals in Swedish disability policy. Despite this, ageing and becoming old with intellectual disability has been given very little attention in policy documents and guidelines regarding support and service provided for this group. This thesis aims to explore ageing and participation among older people with intellectual disabilities who live in a group homes in accordance to the Swedish Disability Act. The focus has been on the group of people who were born before or around 1960. This group belongs to a generation that share unique experiences. They have lived a long life with disability, and they have experienced first-hand the development of the Swedish disability policy that started in the 1960s and resulted in today’s disability policy. These experiences carried through life course are likely to influence this group’s opportunities to participate as they age and reach later life. The thesis has a multiple methodological approach. Participant observations were executed and combined with individual semi-structured interviews with older people with intellectual disabilities as well as group home staff. The results of this thesis show that there is a discrepancy between how older people with intellectual disabilities experience ageing and later life and how these in turn are described by the staff. The thesis also reveals how aging and becoming old is not given particular attention to in everyday discussions in the group home, and that aging is understood mainly as a physical phenomenon. The results show that the formal organizational culture of the group home is weak in relation to ageing and becoming old with intellectual disability. This is because the staff perceives a lack of preparation, discussion and working methods on how to support participation among older residents. The results also show, however, that the residents’ age does play an important role for the staff’s perceptions and attitudes regarding participation of the older residents. The concept of participation is described and operationalized as a social contextual doing, and as an aspiration to create a sense of coherence or experience of meaning and security at home. Finally, this thesis underlines that the life course unique to persons growing old with intellectual disabilities may influence the opportunities for and the experience of participation in the group home.
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| 6. |
- Landberg, Katarina, 1972-
(författare)
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TERMINAL FLOWER2, the Arabidopsis HETEROCHROMATIN PROTEIN1 Homolog, and its Involvement in Plant Development
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the characterization of the Arabidopsis thaliana mutant terminal flower2 (tfl2), the cloning of the corresponding gene, and the analysis of TFL2 function in plant development. The tfl2 mutant is pleiotropic, exhibiting early floral induction in both long and short day conditions, a terminating inflorescence and dwarfing. TFL2 was isolated using a positional cloning strategy, and was found to encode a homolog to HETEROCHROMATIN PROTEIN1 (HP1), previously identified in yeast and animals where it is involved in gene regulation at the level of chromatin, as well as in the structural formation of constitutive heterochromatin. Investigating the light response during seedling photomorphogenesis I found that the tfl2 hypocotyl is hypersensitive to red and far-red light and that tfl2 is impaired in phytochrome mediated light responses such as the shade avoidance response. In the tightly regulated transition to flowering, we have shown that tfl2 might contribute to the interpretation of both external signals such as light and temperature as well as endogenous cues, via FCA, in the autonomous pathway. The Arabidopsis inflorescence meristem is indeterminate, and TFL2 possibly acts to maintain this indeterminate fate by repression of the floral meristem genes APETALA1 and AGAMOUS. In yeast two hybrid experiments TFL2 was shown to interact with IAA5, a protein with suggested functions in auxin regulation. Further, in tfl2 mutants the levels of the auxin indole-3-acetic acid decrease with age in aerial tissues, suggesting a function of TFL2 in regulation of auxin homeostasis and response. In summary, TFL2 contributes to regulation of several aspects of plant development, in accordance with the mutant phenotype and the identity of the TFL2 protein.
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| 7. |
- Larsson, Annika
(författare)
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Automation and the nature of driving - The effect of adaptive cruise control on drivers' tactical driving decisions
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advanced driving assistance systems that offer support by operating for example longitudinal control will have an effect on the transport system. Previous studies have also shown that drivers may be slower to respond in hazardous situations with systems like adaptive cruise control (ACC) engaged, if the system suddenly fails. Little understanding has, so far, emerged to explain why. In this thesis, a situated approach to cognition was used to explain how the drivers’ goals and priorities might change with the opportunity of delegating control to a system. Additionally, drivers’ tactical driving decisions were studied to determine how a system such as ACC is integrated into driving. Such changes could, possibly, impact measures like response times as well. The research focused on how drivers handle the addition of ACC to their drive, especially when managing traffic conflicts. Traffic conflicts are not rare events, but form part of everyday driving. Three methods were used: A questionnaire addressing drivers’ understanding of system limitations, a simulator study on handling traffic conflicts when using ACC, and a database study of a field operational test comparing driver responses with and without ACC. The studies show that drivers do take system behaviour into account when handling traffic conflicts, sometimes allowing the system to act, sometimes by resuming manual control themselves. Previous experience with ACC was also found to affect not only drivers’ knowledge of system limitations, but also their response time to unwanted system behaviour. Drivers were, as previously found, slower to respond with automation than without in simulated driving. In contrast, when studying driver response times in the field test, drivers were faster to respond to a cut-in situation with ACC active than without. The freedom of drivers to use the system as they wish may cause it to be used under different circumstances than in simulator studies, thus explaining the inconsistency with previous results. The results of this thesis indicate that tactical driving behaviour in common traffic situations is an important factor when discussing the effects of ACC and other advanced driver assistance systems. Thus, the cases in which driving is affected by the system are extended from system failures to a wide range of different situations. Merely using operational measures will miss this aspect, thus risking a depiction of driving with automation as more risky than it is. Rather, driving with automation needs to be studied from a tactical perspective, determining first how the systems are being used. Only then can the relevant operational measures be studied.
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| 8. |
- Larsson, Annika, 1958-
(författare)
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Klädd Krigare : Skifte i skandinaviskt dräktskick kring år 1000.
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Using textiles as clues, it is shown that, like in the rest of Scandinavia, there is a legible societal shift in favour of a new Christian organization as early as around year 1000 even in the central parts of what is now Sweden, including the, according to Adam of Bremen, “pagan” Mälar valley. During a period of at least a hundred and fifty years, the Mälar valley with Birka in the centre had enjoyed eastern trade, which is reflected in the rich finds of oriental textile fragments in the Birka graves. From archaeological material, images, texts, coins and runic inscriptions it is possible to assess the importance of codes expressed in the dress. Interpretations of the original Rigsthula texts suggest that it belong in an early Christian context, and is reflecting dress practices found in, among other sources, the Bayeux tapestery and early Scandinavian coins. The textiles from Birka differ markedly from the textiles from Sigtuna, this since they are traces from two completely different societies. Birka textiles show contacts with a steppe nomadic culture, while the Sigtuna textiles and runic inscriptions are witnesses of contacts with advanced Christian workshop cultures like Byzantium.
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| 9. |
- Larsson, Annika, 1975-
(författare)
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Medin amyloid - a matter close to the heart : Studies on medin amyloid formation and involvement in aortic pathology
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amyloidoses are a group of protein misfolding diseases characterized by deposits of insoluble fibrillar protein aggregates. Medin amyloid, which is the focus of this thesis, appears in the media of the thoracic aorta in nearly all individuals over 50 years. The fibrils are derived from a 50 amino acid residue fragment of the precursor protein lactadherin. How medin amyloid arises is unknown, but in paper I we demonstrated, with immunohistochemical and in vitro binding experiments, that both lactadherin and medin interact with elastin, implying that the elastic fibre is central in amyloid formation. In paper II, we further showed that the last 18-19 amino acid residues constitute the amyloid-promoting region. In paper III, the consequence of medin deposition was investigated. Aortic specimens from patients with thoracic aorta aneurysm and dissection were examined for medin content. The tissue findings indicated that the two disease groups contained more medin oligomers than normal aortas. Interestingly, recent reports demonstrate that the toxicity of amyloid proteins is attributed to prefibrillar oligomeric aggregates rather than to mature fibrils. In support of this finding, we observed that prefibrillar medin, in contrast to medin fibrils, was toxic in cell culture. Amyloid formation is a nucleation-dependent process. Addition of preformed fibrils to an amyloid protein solution dramatically accelerates fibrillation, a phenomenon called seeding. In paper IV, serum amyloid A-derived (AA) amyloid was found co-localized with medin deposits in the aorta. In vitro, medin fibrils enhanced the formation of AA fibrils, indicative of a seeding mechanism. The data are of great importance as they suggest that one type of amyloid is capable of inducing fibrillation and deposition of another amyloid type. In conclusion, the results of this thesis shed light on how medin is formed, the function of lactadherin and the consequences of medin deposition for aortic pathology.
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| 10. |
- Larsson, Birgitta, 1965-
(författare)
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Treatment for childbirth fear with a focus on midwife-led counselling : A national overview, women’s birth preferences and experiences of counselling
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Many women experience childbirth fear to such an extent that it seriously interferes with the woman’s daily life and affects her mental well-being.Aim: The overall aim was to conduct an overview of the midwife-led counselling for childbirth fear in Sweden, to investigate women’s birth preferences and to describe their experiences of treatment on childbirth fear, with focus on midwife-led counselling.Methods: Study I is a cross-sectional study where 43 out of 45 maternity clinics responded to a questionnaire regarding midwife-led counselling. Study II is a longitudinal survey where 889 women participated of whom 70 received counselling. Data were collected by questionnaires in mid-pregnancy, two months and finally, one year after birth. Study III is a randomised controlled study with 258 participating women assessed with childbirth fear. It compares Internet-based cognitive behaviour therapy (ICBT) with midwife-led counselling. Data were collected by questionnaires twice during pregnancy and two months after birth. Study IV is a qualitative interview study using thematic analysis, including 27 women who received midwife-led counselling during pregnancy.Results: Overall, midwife-led counselling was perceived as empowering by the women and increased their confidence when facing birth. The preference for a caesarean section decreased during pregnancy and the majority had a normal vaginal birth but an increase in preference for caesarean section appeared after birth. Half of the women who received treatment for childbirth fear experienced a less than positive birth. Women who had a positive birth experience voiced that the contributing factors were the self-confidence received from counselling and the support from the midwife during birth. Decreased or manageable fear was expressed by the women after counselling and birth, which in turn brought a strengthened confidence for a future pregnancy and birth. Furthermore, major differences exist in counselling for childbirth fear throughout the clinics in Sweden.Conclusion: Midwife-led counselling improved women’s confidence toward giving birth and fear was perceived as manageable. Continuous support is crucial to experience birth as positive. Although women’s preferences for caesarean section did not change over time, few women gave birth with a caesarean section without medial reason.
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