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Disputationer

Via universitetsbibliotekets databas över doktorsavhandlingar kan du söka publicerade doktorsavhandlingar vid Göteborgs högskola/universitet från 1902 och framåt. Databasen innehåller också information om kommande disputationer.

UB:s databas över doktorsavhandlingar

Kommande disputationer

Three-dimensional guidance for Endovascular Aortic Repair

[2017-09-25] Title: Three-dimensional guidance for Endovascular Aortic Repair Authors: Koutouzi, Giasemi Abstract: Image fusion (IF) of preoperative computed tomography (CT) with intraoperative cone-beam CT (CBCT) is a potentially powerful tool for guidance during endovascular aortic repair (EVAR). It may improve intraoperative anatomic visualization and reduce doses of radiation and contrast medium. The technique is still new, however, and has not yet been standardized for routine use in all centers that have the facilities to perform it. The main aims of this thesis were: 1. to describe the use of orthogonal rings for 3D guidance during EVAR and to investigate sources of registration and overlay error; 2. to investigate the feasibility of combining 3D fusion with carbon dioxide (CO2 ) digital subtraction angi-ography (DSA) during EVAR, in order to reduce the dosage of iodinated contrast; 3. to determine whether 3D image fusion can be used to localize intercostal arteries during thoracic EVAR; 4. to evaluate the performance of a feature-based algorithm for 3D3D image registration; and 5. to assess iliac artery deformation due to stiff endovascular devices during EVAR. In a prospective single-center study (I) involving 19 patients undergoing EVAR, we found that automatic intensity-based registration only was insufficient for guidance. Manual vertebrae-based registration was sufficient in only 37% of the patients. After aorta-based registration, the median overlay alignment error for the lowest renal artery at pre-deployment DSA was 2 mm (range 0‒5 mm) sideways and 2 mm (range 0‒9 mm) longitudinally. Study II was a feasibility study showing that EVAR can be performed with 3D image fusion guidance combined with CO2 DSA, instead of iodinated contrast medium DSA, which was only used for the completion angiography. Study III was also a feasibility study showing that image fusion can facilitate thoracic EVAR (TEVAR) by visualization of intercostal arteries adjacent to the distal landing zones. In study IV, a feature-based and an intensity-based registration algorithm were compared using datasets from 14 patients who underwent complex EVAR. The feature-based algorithm was more robust and accurate. The median 3D error for the feature-based algorithm was 2.3 mm (range 0.4‒7.9 mm) as compared to 31.6 mm (range 0.5‒112.2 mm) for the intensity-based algorithm (p < 0.001). In study V, preoperative, postoperative, and intraoperative 3D image datasets were reviewed in order to assess iliac artery deformation by stiff endovascular devices during EVAR. The common iliac artery was shorter in both the intraoperative images (p < 0.001) and the postoperative images (p = 0.015) relative to the preoperative CTA. Furthermore, there was a dislocation of the aortic bifurcation in the cranial direction (93%) and a dislocation of the iliac bifurcation in the ventral direction (89%). The intraoperative C-arm angulation for optimal projection of the iliac bifurcation increased with 21 ± 43 degrees in the contralateral oblique direction relative to the angle predicted from the preoperative CTA. In conclusion, 3D image fusion for EVAR guidance is a promising technique allowing improved intraoperative visualization of critical anatomical structures. However, limitations in registration accuracy and anatomy distortion compensation mandate further research.

The impact of railway vibration and noise on sleep

[2017-09-25] Title: The impact of railway vibration and noise on sleep Authors: Smith, Michael Abstract: Sleep is a vital component of good health, and sleep loss is associated with impaired cognition, decreased psychomotor performance, cardiovascular disease, adverse effects on endocrine and metabolic function, negative mood, impaired memory, and more. A growing burden of freight transporta-tion on global railway networks will likely lead to an increase in nocturnal vibration and noise at nearby dwellings. However, there is currently limited knowledge on how railway freight vibration and noise may disrupt sleep. Over a series of laboratory studies in young healthy adults, the effect of vi-bration and noise from railway freight was investigated. Objective sleep was recorded with polysomnography, cardiac activity was recorded with elec-trocardiography and subjective sleep quality and disturbance was recorded with questionnaires. Increased cardiac activation occurred at vibration am-plitudes only slightly above wakeful perceptual detection thresholds. Arousals, awakenings and alterations of sleep structure began to manifest at only slightly higher vibration amplitudes. With increasing vibration ampli-tude, heart rate and the probability of event-related cortical response in-creased in a dose-dependent manner, with accompanying adverse effects on perceived sleep quality and sleep disturbance. Perceived disturbance was more pronounced among noise-sensitive individuals, although no signifi-cant physiologic differences were found relative to non-sensitive counter-parts. Rather than affecting overall sleep architecture, vibration and noise interfered with the normal rhythms of sleep, although the impact of this on long-term physical and mental health is currently unclear. Cardiac response persisted with increasing number of events, indicating an absence of habit-uation. Vibration and noise were additive regarding their effect on cortical arousal and sleep stage change, demonstrating that both exposures differen-tially contribute to sleep fragmentation. From a public health perspective, interventions to protect the sleep of populations near railway lines should therefore consider both exposure types.

Essays on behavioral economics: Nudges, food consumption and procedural fairness

[2017-09-22] Title: Essays on behavioral economics: Nudges, food consumption and procedural fairness Authors: Kurz, Verena Abstract: Decreasing meat consumption holds significant potential for the reduction of human-induced greenhouse gas emissions and the mitigation of climate change. Fostering behavioral change to reduce climate emissions related to food consumption is challenging and requires new strategies based on an understanding of human decision-making. The first two chapters of this thesis are devoted to studying the potential of nudging interventions to reduce meat consumption in different contexts. The third chapter explores the role procedural fairness plays for solving a coordination problem. We study how an informal rule in the form of recommendations affects efficiency, and how the results vary with changes in the fairness of the recommendations. This thesis highlights the importance of contextual factors for human decision making and its implications for policy.

Prevalence and treatment of patients with heart failure with special emphasis on diuretics

[2017-09-21] Title: Prevalence and treatment of patients with heart failure with special emphasis on diuretics Authors: Parén, Pär Abstract: Background: Heart failure (HF) is a major health problem worldwide with an estimated prevalence of about 1-2% in the Western world. The temporal trend for prevalence of HF has never been investigated in a nationwide population. In patients with HF diuretic treatment is recommended for relief of congestive symptoms. Over 80% of all patients with HF are estimated to be treated with diuretics. However, information about the temporal trend for diuretic treatment in a nationwide population is lacking and the prognostic effect of diuretic treatment in patients with HF has never been studied in a randomized clinical trial. Diuretics have been associated with increased mortality in selected populations with HF but the association of diuretics with mortality in unselected Western world patients discharged from a hospitalization for HF or in unselected outpatients with HF has not been studied. Aim: The aims of this thesis was to study trends for prevalence of patients hospitalized with HF 1990-2007, trends for diuretic treatment in patients hospitalized for HF 2004-2011, the association of diuretic treatment at hospital discharge from a hospitalization for HF with short- and long-term mortality, and to evaluate diuretic treatment as a prognostic predictor for long-term mortality in outpatients with HF. Methods and results: Data from several different Swedish registries were linked in these studies. Patients hospitalized with a primary or secondary diagnosis of HF aged 19-99 years 1990-2007 were included in Paper I. An increase in age-adjusted prevalence of HF until 1995 and a decrease from 2002 to 2007 was observed. Prevalence of HF in people aged less than 55 years increased throughout the observational period. In absolute num-bers, patients with HF older than 85 years increased by 77% from 1990 to 2007 (Paper I). Patients with a fi rst-time hospitalization for HF that survived for 18 months or more after discharge were included in Paper II. Post-discharge diuretic treatment and doses decreased 2005-2014 and coincided with increased neuro-hormonal antagonist treatment rates (Paper II). Patients recorded in the Swedish HF registry 2004-2011 with known diuretic treatment status were included in Paper III and IV. Diuretic treatment at hospital discharge had a neutral association with short-term mortality but was associated with in-creased long-term mortality (Paper III). Diuretic treatment in unselected outpatients with HF was independently associated with increased long-term mortality but did not improve a previously known model for prediction of 3-year mortality (Paper IV). Conclusions: The prevalence of HF decreased 2002-2007 but may increase in the future due to increased prevalence in young persons and the demographic transition. If the observed trend for decreased post-discharge diuretic treatment rates and doses in patients with HF 2005-2014 was related to the observed coinciding increase of treatment with neuro-hormonal antagonists was not answered by this study. If the observed associations of diuretic treatment with increased long-term mortality in real-life patients with HF was related to a direct prognostic effect of diuretic treatment or to diuretic treatment as a marker for HF disease severity remains unknown.

Microbial communities in anammox and nitrifying biofilms

[2017-09-19] Title: Microbial communities in anammox and nitrifying biofilms Authors: Suarez, Carolina Abstract: Excess of nitrogen in water bodies causes eutrophication. One important source of nitrogen is the effluent from wastewater treatment plants (WWTPs). Nitrogen in wastewater is most commonly removed by nitrification-denitrification. During nitrification-denitrification, aerobic ammonia oxidizing bacteria (AOB) oxidize ammonium to nitrite, which is in turn oxidized to nitrate by their syntrophic partners; aerobic nitrite oxidizing bacteria. Heterotrophic denitrifiers can then convert the nitrate to harmless nitrogen gas. Partial-nitritation anammox (PNA) is an alternative process for nitrogen removal which is today used for treatment of warm and concentrated sidestreams (reject water after anaerobic sludge digestion) at WWTPs, with potential to be used also for the mainstream of wastewater. PNA relies on bacteria capable of anaerobic ammonium oxidation (anammox) using nitrite as electron acceptor. Together with AOB they convert ammonia to nitrogen gas. To increase retention of biomass in bioreactors, bacteria are often grown in biofilms, microbial communities attached to a surface. The overall aim of this thesis was to study nitrifying- and anammox communities in biofilms, using moving bed biofilm reactors as a model system. Reactor performance, microbial community dynamics and biofilm structure of PNA reactors operated a low temperature or low ammonium concentration were studied, showing community stability, but process instabilities. Differences in composition and ribosomal content between reject- and mainstream communities were investigated, showing that both abundance and bacterial activity are important for explaining differences in process rates. Basic question about biofilm ecology were also studied. Here, for the first time, predation of anammox bacteria in biofilms was demonstrated. Furthermore, it was shown how biofilm thickness influences nitrifying communities and biofilm functions, with differences in community composition and ecosystem function. Together these results help to unravel the link between community composition and bioreactor function for anammox and nitrifying biofilms, which can lead to development of new technologies and strategies for N-removal in wastewater.

Fritidshem eller servicehem? En etnografisk studie av fritidshem i tre socioekonomiskt skilda områden

[2017-09-18] Title: Fritidshem eller servicehem? En etnografisk studie av fritidshem i tre socioekonomiskt skilda områden Authors: Andishmand, Catarina Abstract: In recent decades there has been decreased resources and larger groups of children in the leisure-time centres. Statistics show major differences between leisure-time centres in terms of staff education, group size, staffing levels and the number of children enrolled at each leisure-time centre. The overall aim of the thesis is to study social practices in leisure-time centres providing after-school care. Based on Anthony Giddens' theory of structuration, an ethnographic study was conducted of everyday life at leisure-time centres in three socio-economically diverse areas. Fieldwork was conducted at each leisure-time centre over the course of one semester. The study shows how children and adults talk about their neighbourhoods and schools. It also shows the actors notions about the mission of the leisure-time centres, expressed through the actors' talk and interactions, their day-to-day routines and everyday social encounters. In conclusion, the study shows that the geographic location, resources, staff skills, group sizes and children's socio-economic backgrounds together play major roles in the social practices and activities organised at the leisure-time centres. The social changes and developments of recent decades are noticeable in all leisure-time centres. Housing segregation along with freedom of school choice all had consequences for the leisure-time centres. For children attending the same leisure-time centres, the groups become increasingly homogeneous in line with the children's ethnic and socio-economic backgrounds. The results also show that leisure-time centres with large groups of children have reduced opportunities to provide a good learning environment. It becomes evident that the social practices in the leisure-time centres reproduce the contextual conditions, and risk reproducing structural differences in children's lives.

Power Outages, Increasing Block Tariffs and Billing Knowledge

[2017-09-16] Title: Power Outages, Increasing Block Tariffs and Billing Knowledge Authors: Meles, Tensay Hadush Abstract: Preferences for Improved Electricity Services in Developing Countries: Household’s Defensive Behavior and Willingness to Pay Access to electricity has received much attention but its reliability has been given less focus. Thus, uninterrupted power supply remains a critical challenge facing households in low-income developing countries. In this paper, we use data on household defensive expenditures and willingness to pay (WTP) to analyze households’ preference for improved electricity supply. We provide an estimate of average monthly defensive expenditures at different monthly hours of power outages using the generalized propensity score method – a continuous treatment matching. Furthermore, we elicit households’ willingness to pay for improved electricity supply using the contingent valuation method. To this end, we use a field survey data from 1,152 sample households in Addis Ababa, Ethiopia. Our results show that the estimated average monthly defensive expenditures is substantial and vary by the monthly hours of power outages. Also, results from the stated preference study show that households are willing to pay 19%–25% of the existing average monthly bill for improved electricity supply. JEL Classification: C21, D12, L94, N77, Q41, Q51 Keywords: Power outages, defensive behavior, willingness to pay, Ethiopia, generalized propensity score Do Consumers Respond to Marginal Prices of Electricity under Increasing Block Tariff? In developing countries, electric and water utilities commonly use increasing block tariff (IBT) as a tool to encourage resource conservation, recover costs, and subsidize low-income consumers. However, it is not clear whether consumers actually respond to marginal prices under IBT. We empirically analyze whether marginal price in an IBT influences residential electricity demand, by combining administrative monthly electricity bill records with a detailed survey of sample households. Results from a bunching analysis and Arellano-Bond estimator show that prices of electricity do not significantly affect monthly electricity consumption. The finding highlights that consumers do not respond to marginal prices under IBT if electricity price is low or if they are unaware of the pricing schedules and have difficulty in understanding how their bills are computed in such tariff structures. This, in turn, has severe implications for the efficacy of the policy objectives of IBT. JEL Classification: C23, D12, L11, L94, Q21 Keywords: Residential electricity demand, shared connections, increasing block tariff, bunching analysis, panel data Billing Knowledge and Consumption Behavior: Experimental Evidence from Nonlinear Electricity Tariffs Increasing block tariff for electricity services is a popular tariff structure in developing countries with the ambition to promote resource conservation among users with high consumption and to provide subsidy for low-income consumers. However, in a complex pricing structure, such as increasing block tariff (IBT), consumers may not know the marginal price they face and might not fully understand how their bill is computed. Thus, in this study, we investigate whether educating consumers about how their monthly electricity bill is calculated in an IBT structure affects electricity consumption. To evaluate the effect of the treatment, we conduct a field experiment with residential electricity consumers in Ethiopia where electricity price is heavily subsidized and shared connections are common. Using monthly consumption data from the electric meters, we find no statistically significant effect after six months in response to the treatment. Our finding suggests that it is not the lack of billing information that makes residential electricity consumers insensitive to the IBT. Alternative reasons, such as the low electricity price are provided. JEL Classification: C93, D12, D83, H42, L94 Keywords: Billing knowledge, consumer behavior, non-linear electricity price, field experiment ISBN: 978-91-88199-27-0 (PRINTED) 978-91-88199-28-7(PDF) Contact information: Tensay Hadush Meles, Department of Economics, School of Business, Economics and Law, University of Gothenburg, P.O. Box 640, SE 405 30, Gothenburg, Sweden. E-mail: tensay.meles@economics.gu.se

Ordens kraft : Politiska eder i Sverige 1520-1718

[2017-09-14] Title: Ordens kraft : Politiska eder i Sverige 1520-1718 Authors: Nauman, Sari Abstract: Political oaths were widespread in medieval times, but all over Europe their use dwindled in the early modern period, resulting in the institution being dismantled in many states. In previous research, this decay has been explained by pointing to the emergence of the state in this period, through processes such as bureaucratization, nationalization, and confessionalization, and, later, secularization. However, as some oaths are still in use in modern state systems, the swearing of them seems to be compatible with modern – bureaucratized, nationalized, and secularized – states. If nothing else, this indicates that the standard model for explaining changes in European oath-taking must be questioned. The main purpose of this dissertation is to analyse why political oaths were used in Sweden in the sixteenth and seventeenth centuries, as well as to explain why the usages changed. It is argued that oaths were performative means of instilling trust in a political relationship. Trust was accomplished by an oral utterance, during which the swearer claimed the position of a trustworthy subject. The study encompasses not only how the force of oaths was created, but also how uncertainty regarding the subject’s trustworthiness was handled, by examining its usage in coronations, rebellions, wars and political meetings. The dissertation has four conclusions. First, not only the use of oaths but also the oath event itself underwent changes during the period studied, leading to changes in its performative force. Second, the shaping of the oath event depended on the degree of uncertainty in the specific political relationship. Third, while in the sixteenth century oaths were used to establish trust in political relationships, in the seventeenth century they were re-directed to establish control. Fourth, the shift from trust to control reflected the rise of a written political culture. When political relationships shifted from being characterized by presence and personal contact, to being characterized by distance and impersonal delegation, written oaths were better suited to the situation. Ultimately, the written form transformed the action, for the ability of a political oath to instil trust was linked to its orality. What a written oath could do, though, was help establish control.

Painting from Within - Developing and Evaluating a Manual-based Art therapy for Patients with Depression

[2017-09-13] Title: Painting from Within - Developing and Evaluating a Manual-based Art therapy for Patients with Depression Authors: Blomdahl, Christina Abstract: Aim: The overall aim was to develop and evaluate a manual-based art-therapy programme for patients with depression, and hence, to clarify treatment effects and to describe participants’ experiences of the treatment. The specific aims were: (I) To explore and describe how art therapy works in relation to therapeutic factors, clinical application, and circumstances in the experimental situation, for patients with depression; (II) To explore what experts in the field of art therapy consider to be the main aspects of treatment for patients with depression in clinical practice; (III) To investigate the effects of manual-based Phenomenological Art Therapy in addition to treatment as usual (PATd/TAU) compared with only treatment as usual (TAU) for patients diagnosed with moderate to severe depression; and (IV) To describe and explore the significance of manual-based Phenomenological Art Therapy as experienced by patients diagnosed with moderate to severe depression. Methods: (I) Systematic literature review according to Realist review; (II) Expert survey according to the Delphi technique (Studies I and II were used as a foundation for developing the manual-based Phenomenological Art Therapy for patients with depression (PATd)); to evaluate the effect and experience of PATd, (III) a randomized controlled trial (RCT) with intention-to-treat design was performed; and, thereafter, an interview study with (IV) a Phenomenological approach, according to Reflective Lifeworld Research. Results: (I) eight therapeutic factors were identified: self-exploration, self-expression, communication, understanding and explanation, integration, symbolic thinking, creativity, and sensory stimulation; (II) resulting in four main aspects of art therapy for patients with depression; expression through art-making and verbal communication concerning, depressive thoughts, feelings, life experiences, and physical symptoms. (III) PATd in addition to Treatment As Usual (TAU) showed a significant reduction of depression and an improved return to work compared to participants receiving only TAU. Self-esteem significantly improved, and suicide ideation did not change for either groups. (IV) PATd facilitates meeting oneself in an inner dialogue between the evident and the unaware. The art-making and describing that experience makes oneself and the situation visible, opening up and altering understanding through the inner dialogue. Conclusions: manual-based PATd seems to work as intended, being an effective treatment, and contributes to recovery for patients with moderate to severe depression.

Airborne particulate matter in a Sub-Saharan Africa city: Nairobi, Kenya, and at an Equatorial high altitude site: Mount Kenya

[2017-09-13] Title: Airborne particulate matter in a Sub-Saharan Africa city: Nairobi, Kenya, and at an Equatorial high altitude site: Mount Kenya Authors: Gaita, Samuel Mwaniki Abstract: In Sub-Saharan Africa (SSA), air quality is gravely understudied despite the existing influential factors such a rapid urbanization and population growth that negatively affect the environment. Majority of urban areas in SSA face challenges that include lack of social services, poor infrastructure development, exponential increase of second-hand vehicles and extensive use of biomass-based fuel for energy needs. There is a systemic lack of continuous monitoring of air pollution in most SSA cities and hence it is yet to be seen if SSA will meet the set air quality targets of the sustainable development goals (SDGs) by the year 2030. Although the focus of air quality is on the urban areas, there is a need to monitor atmospheric composition at remote areas in SSA in order to build a baseline level and understand the influence of anthropogenic and natural aerosol sources on regional/global scale. This thesis work sought to study physical and chemical properties of airborne particulate matter (PM) in a typical SSA urban area, Nairobi city, and a high altitude site, Mount Kenya. Results from spatial distribution of black carbon (BC) and PM2.5 (particulate matter less than 2.5 aerodynamic diameter) showed that air quality on the road to the city and within the city is deteriorating. Factor analysis of the PM2.5 results showed that pollution sources were traffic, mineral dust, industrial, combustion, biomass burning, secondary aerosol and aged sea salt. Traffic and mineral dust contributed about 74% of the PM2.5 in Nairobi. Exposure to particulate pollutants was expressed in terms of deposition fractions from the size segregated PM data. The head airways region was found to receive the highest dose (about 86%) compared to the tracheobronchial and pulmonary regions. The reported high PM2.5 and BC concentrations measured along the main street of Nairobi city, indicated the urban population is frequently exposed to elevated pollutants concentrations and thus have high risk factor to respiratory illnesses and lung cancer. Aerosol study from Mount Kenya showed air pollutants are transported from the surrounding and far away sources by local and regional meteorology dynamics. The results from this study provides insight into the air quality issues from pollution sources, exposure to the population and dispersal to remote regions.

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http://earlymoderntown.gu.se/omuniversitetet/aktuellt/Disputationer/
Utskriftsdatum: 2017-09-26