| 1. |
- A. Manneh, Ilana, 1970-
(author)
-
Supporting Learning and Teaching of Chemistry in the Undergraduate Classroom
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- There is agreement in research about the need to find better ways of teaching chemistry to enhance students’ understanding. This thesis aims to contribute to the understanding of how we better support teaching and learning of undergraduate chemistry to make it meaningful and intelligible for students from the outset. The thesis is concerned with examining the interactions between student, specific content and teacher in the undergraduate chemistry classroom; that is, the processes making up the three relations of the didactic triangle. The data consists of observations of students and tutors during problem-solving activities in an introductory chemistry course and interviews with graduate students.Systematic analyses of the different interactions between the student, the chemistry content, and the tutor are made using the analytical tool of practical epistemology analysis. The main findings of the thesis include detailed insights into how undergraduate chemistry students deal with newly encountered content together with didactic models and concrete suggestions for improved teaching and for supporting continuity and progression in the undergraduate chemistry classroom. Specifically, I show how students deal with the chemistry content through a complex interaction of knowledge, experiences, and purposes on different levels invoked by both students and tutors as they interact with each other. Whether these interactions have a positive or negative effect on students’ learning depends on the nature of knowledge, experiences and purposes that were invoked. Moreover, the tutor sometimes invoked other purposes than the ones related to the task at hand for connecting the activity to the subject matter in general. These purposes were not always made continuous with the activity which resulting in confusion among students. The results from these analyses were used for producing hypotheses and models that could support continuity and progression during the activity. The suggested models aim to make the content more manageable and meaningful to students, enabling connections to other experiences and purposes, and helping teachers and tutors to analyze and reflect on their teaching. Moreover, a purpose- and activity-based progression is suggested that gives attention to purposes in chemistry education other than providing explanations of chemical phenomena. The aim of this ‘progression in action’ is to engage students in activities were they can see the meaning of chemical concepts and ideas through their use to accomplish different chemical tasks. A general conclusion is that detailed knowledge about the processes of teaching and learning is important for providing adequate support to both undergraduate students and university teachers in the chemistry classroom.
|
|
| 2. |
- Arnell, Matilda, 1987-
(author)
-
Distribution patterns of fleshy-fruited woody plants at local and regional scales
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- Fleshy-fruited woody plants share a long history with humans, providing us with food and wood material. Because of this relation, we have actively moved some of these plants across landscapes and continents. In Sweden, these species are often found in open and semi-open habitats such as forest edges, their fruits are most often dispersed by birds and their flowers are, with some exceptions, pollinated by insects. In this thesis my overall aim was to map and analyse distribution patterns of fleshy-fruited woody plants in Sweden to expand our knowledge on the mechanisms governing their distributions. First, I mapped a population of the early flowering, fleshy-fruited shrub Daphne mezereum (common mezeron, tibast) and surveyed the reproduction and fruit removal of all individuals (chapter I). My main aim was to investigate to what extent reproduction and fruit removal was affected by local distribution patterns. Secondly, I mapped local distribution patterns of fleshy-fruited woody species and analysed spatial associations between life stages and species (chapter II). My main aim was to relate these spatial associations to predictions of how bird dispersal would shape the local distribution patterns and the hypothesis that birds create ‘wild orchards’. Thirdly, I digitized historical maps and surveyed fleshy-fruited woody species along transects across landscapes (chapter III). My aim was to examine the hypothesis that these species accumulate in open and semi open habitats created by human land use. Fourthly, I estimated range filling of woody plants in Sweden at a 1 km2 resolution (chapter IV). My aim was to compare these estimates among species with different dispersal systems to understand the effect of dispersal on the occupancy of woody species at regional scales.I found the distribution patterns of these species to be affected by past and present land use, supporting the hypothesis that these plants accumulate in open habitats. Occurrences of species in this guild in todays’ forest are positively related to past human land use (chapter III) and the density of D. mezereum increases with decreasing distances to forest edges (chapter I). This accumulation may in part be explained by the positive effect of forest edges on reproduction and fruit removal (chapter I). I further found local distribution patterns of this guild and the individual species to be aggregated (chapter I and II), and spatial associations between saplings and reproductive individuals to support the ‘orchard’ hypothesis (chapter II). The aggregated pattern of fruit-bearing individuals was positively related to fruit removal whereas aggregated flowering individuals was negatively related to fruit set (chapter I). On the regional scale, I found these species to occupy climatically suitable areas, or fill their potential ranges, to a less extent that wind dispersed trees and shrubs (chapter IV), which may indicate dispersal limitation.In conclusion, the behaviour of birds and humans have shaped, and still shape the current distribution of fleshy-fruited trees and shrubs in Sweden, resulting in accumulation in open habitats and locally aggregated distribution patterns. Changing land-use practices and potential mismatches between fruit maturation and bird dispersal with a changing climate may thus result in even lower chances of these species to fill their potential ranges, due to habitat losses and dispersal limitations at local and regional scales.
|
|
| 3. |
- Awad, Amar, 1988-
(author)
-
Functional brain imaging of sensorimotor dysfunction and restoration : investigations of discomplete spinal cord injury and deep brain stimulation for essential tremor
- 2022
-
Doctoral thesis (other academic/artistic)abstract
- The nervous system exists to generate adaptive behaviour by processing sensory input from the body and the environment in order to produce appropriate motor output, and vice versa. Consequently, sensorimotor dysfunction is the basis of disability in most neurological pathologies. In the current thesis, I explore two conditions with different types and degrees of sensorimotor dysfunction by means of functional magnetic resonance imaging (fMRI). In part 1, I assess residual sensory connections to the brain in clinically complete spinal cord injury (SCI) with seemingly complete loss of sensorimotor function below the injury level. In part 2, fMRI is combined with deep brain stimulation (DBS) to investigate interventional mechanisms of restoring dysfunctional sensorimotor control in essential tremor (ET).Part 1: SCI disrupts the communication between the brain and below-injury body parts, but rarely results in complete anatomical transection of the spinal cord. In studies I and II, we demonstrate somatosensory cortex activation due to somatosensory (tactile and nociceptive) stimulation on below-level insensate body parts in clinically complete SCI. The results from studies I and II indicate preserved somatosensory conduction across the spinal lesion in some cases of clinically complete SCI, as classified according to international standards. This subgroup is referred to as sensory discomplete SCI, which represents a distinct injury phenotype with an intermediate degree of injury severity between clinically complete and incomplete SCI.Part 2: ET is effectively treated with DBS in the caudal zona incerta, but the neural mechanisms underlying the treatment effect are poorly understood. By exploring DBS mechanisms with fMRI, DBS was shown to cause modulation in the activity of the sensorimotor cerebello-cerebral regions during motor tasks (study III), but did not modulate the functional connectivity during resting-state (study IV).fMRI is a valuable tool to investigate sensorimotor dysfunction and restoration in SCI and DBS-treated ET. There is evidence for sensory discomplete SCI in about half of the patients with clinically complete SCI. DBS modulates DBS modulation of the activity in the sensorimotor cerebello-cerebral circuit during motor tasks, but not during resting-state, is action-dependent.
|
|
| 4. |
- Dahlgren, Johan Petter, 1978-
(author)
-
Linking plant population dynamics to the local environment and forest succession
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Linking environmental variation to population dynamics is necessary to understand and predict how the environment influences species abundances and distributions. I used demographic, environmental and trait data of forest herbs to study effects of spatial variation in environmental factors on populations as well as environmental change in terms of effects of forest succession on field layer plants. The results show that abundances of field layer species during forest succession are correlated with their functional traits; species with high specific leaf area increased more in abundance. I also found that soil nutrients affect vegetative and flowering phenology of the forest herb Actaea spicata. The effect of nutrients shows that a wider range of environmental factors than usually assumed can influence plant phenology. Moreover, local environmental factors affected also the demography of A. spicata through effects on vital rates. An abiotic factor, soil potassium affecting individual growth rate, was more important for population growth rate than seed predation, the most conspicuous biotic interaction in this system. Density independent changes in soil potassium during forest succession, and to a lesser extent plant population size dependent seed predation, were predicted to alter population growth rate, and thereby the abundance, of A. spicata over time. Because these environmental factors had effects on population projections, they can potentially influence the occupancy pattern of this species along successional gradients. I conclude that including deterministic, as opposed to stochastic, environmental change in demographic models enables assessments of the effects of processes such as succession, altered land-use, and climate change on population dynamics. Models explicitly incorporating environmental factors are useful for studying population dynamics in a realistic context, and to guide management of threatened species in changing environments.
|
|
| 5. |
- Jonsson, Ing-Marie, 1960-
(author)
-
Social and Emotional Characteristics of Speech-based In-Vehicle Information Systems : Impact on Attitude and Driving Behaviour
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Modern vehicles use advanced information systems in vehicles to provide and control a wide variety of functions and features. Even modest vehicles today are equipped with systems that control diverse functions from air-conditioning to high quality audio/video systems.Since driving requires the use of eyes and hands, voice interaction has become more widely used by in-vehicle systems. Due to the technical complexity involved in voice recognition, focus has been on issues of speech ecognition. Speech generation is comparatively simple, but what effect does the choice of voice have on the driver? We know from human-human interaction that social cues of the voice itself influence attitude and interpretation of information. Introducing speech based communication with the car changes the relationship between driver and vehicle. So, for in-vehicle information systems, does the spoken voice matter?The work presented in this thesis studies the effects of the voice used by invehicle systems. A series of studies were used to answer the following questions: Do the characteristics of voices used by an in-vehicle system affect driver’s attitude? Do the characteristics of voice used by an in-vehicle system affect driver’s performance? Are social reactions to voice communication the same in the car environment as in the office environment?Results show that voices do matter! Voices trigger social and emotional effects that impact both attitude and driving performance. Moreover, there is not one effective voice that works for all drivers. Therefore an in-vehicle system that knows its driver and possibly adapts to its driver can be the most effective. Finally, an interesting observation from these studies is that social reactions to voice communication in the car are different than in the office, Similarity attraction, an otherwise solid finding in social science, did not hold all studies. It is hypothesized that this difference can be related to the different kinds of task demands when driving a car or working in an office environment.
|
|
| 6. |
- Kumar Wagri, Naresh, 1988-
(author)
-
Assessment of bio-based fuel ash effects on magnesia refractory materials in quicklime production kilns
- 2023
-
Doctoral thesis (other academic/artistic)abstract
- Limestone is calcined into quicklime in lime kilns at temperatures above 1000°C. Heat is supplied through combustion inside the kilns, which are insulated with a lining of refractory bricks to mitigate heat loss and to protect the kiln from the hot, chemically aggressive, and mechanically abrasive environment. While magnesia bricks have proven to be effective lining materials, they are still susceptible to extensive wear in lime kilns, especially in the burn zone. Refractory corrosion, in particular, can occur when melted fuel ash infiltrates the refractory materials through pores and small cracks. This resultant wear can lead to high maintenance and operational costs, often due to unplanned kiln shutdowns.To reduce the release of fossil-based carbon dioxide into the atmosphere from lime production kilns, there is a growing interest in introducing bio-based fuels with only relatively minor modifications to the process. Biomass fuels can be sourced from bio-based waste streams from industries or be specifically cultivated for combustion. However, the ash content and properties of bio-based fuels tend to be problematic from an ash chemistry perspective. Therefore, before introducing a new fuel source, it is essential to investigate its potential effects on the kiln lining material. In this thesis work, the interactions between melted olive pomace ash and coal ash with commercially available magnesia refractory materials, primarily composed of periclase (MgO) with minor amounts of spinel (MgAl2O4), were studied. A procedure for quantifying the intrusion depths was described. Refractory samples were exposed to the fuel ashes under a simulated lime kiln atmosphere with high CO2 levels at 1200 and 1400°C for 15 and 60 minutes. Cold crushing strength tests were conducted on refractory samples exposed to coal and olive pomace ash, along with CaO powder, at 1400°C for 96 hours. Additionally, postmortem analyses of spent MgO-based refractory bricks were carried out to investigate their chemical characterization and resistance to slag attack after serving as part of the lining in a quick lime rotary kiln for six months.The morphology and elemental compositions of the exposed samples were examined using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystalline phases were investigated with powder X-ray diffraction. Thermodynamic equilibrium calculations were performed to further investigate the ash’s melting behavior in contact with the refractories.The results indicated that the potassium-rich olive pomace ash exhibited a greater tendency to infiltrate compared to the silicon-rich coal ash, while the latter formed a glassy melt layer on top of the refractory samples. The ash slags primarily infiltrated through the porous matrix and grain boundaries of the refractory materials. Also, refractory phases were observed in both types of ashes, indicating migration of refractory constituents. K2MgSiO4 phase was found in the olive pomace ash residues on top of the samples, both for the 1200°C and 1400°C exposures. Similarly, Al6Si2O13 phase was dominant in the residual coal ash, in both the 1200°C and 1400°C exposed samples. None of these phases were present in the original ashes.The results of the postmortem analysis revealed that there was no potassium (K) from the fuel ash present on the hot side of the refractory bricks. However, some K was detected in the middle and back parts of the bricks. On the other hand, some phases, possibly connected to degradation, could be found on the hot side of the bricks, where most of the wear was observed.The crushing strengths increased after exposure for all samples, except for those exposed exclusively to coal ash. One possible explanation for this is that the refractory materials exhibited a sintered structure, as a result of their interaction with the ashes and CaO. However, in the samples exposed to coal ash, forsterite (Mg2SiO4) was identified, which can be considered a corrosion product.
|
|
| 7. |
- Marteinsdóttir, Bryndís, 1980-
(author)
-
Plant community assembly in grazed grasslands
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- Species assembly into local communities from the surrounding region can be caused either by species failure to reach the site (i.e. seed limitation) or to establish (i.e. establishment limitation). The aim of this thesis was to investigate plant species assembly and to determine the relative importance of different factors in that process.In a cultivated landscape in southeast Sweden, plant community assembly was studied in grazed ex-arable fields. Community assembly from the surrounding region into the local community was explored using trait-based null models and seed sowing and transplanting experiments. The influence of local environmental factors and landscape history and structure on community assembly was also studied. In addition, differences in species assembly between ex-arable fields and semi-natural grasslands were explored.Seed limitation was the strongest filter on local community assembly. Only a fraction (36%) of species in a region dispersed to a local site and adding seeds/transplants increased species establishment. Species abundance at the regional scale, species dispersal method and seed mass strongly influenced which species arrived at the local sites. Establishment limitation also affected the assembly. Of species arriving at a site 78% did establish, seedling survival was low and which species established was influenced by species interactions, local environmental conditions and stochastic events. In addition, landscape structure that determined the species richness in the regional species pool influenced the local assembly. The comparison between assembly in ex-arable fields and semi-natural grasslands indicated that the main cause of difference in species assembly between them was difference in their age.The main conclusion of this thesis is that regional processes are more important than local factors in determining plant community assembly.
|
|
| 8. |
- Pham, Lan Anh, 1991-
(author)
-
On avoiding and completing colorings
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- All of my papers are related to the problem of avoiding and completing an edge precoloring of a graph. In more detail, given a graph G and a partial proper edge precoloring φ of G and a list assignment L for every non-colored edge of G, can we extend φ to a proper edge coloring of G which avoids L? In Paper I, G is the d-dimensional hypercube graph Qd, a partial proper edge precoloring φ and a list assignment L must satisfy certain sparsity conditions. Paper II still deals with the hypercube graph Qd, but the list assignment L for every edge of Qd is an empty set and φ must be a partial proper edge precoloring of at most d-1 edges. In Paper III, G is a (d,s)-edge colorable graph; that is G has a proper d-edge coloring, where every edge is contained in at least s-1 2-colored 4-cycles, L must satisfy certain sparsity conditions and we do not have a partial proper edge precoloring φ on edges of G. The problem in Paper III is also considered in Paper IV and Paper V, but here G can be seen as the complete 3-uniform 3-partite hypergraph K3n,n,n, where n is a power of two in paper IV and n is an even number in paper V.
|
|
| 9. |
- Sundström, Johan, Professor, 1971-, et al.
(author)
-
Risk factors for subarachnoid haemorrhage : a nationwide cohort of 950 000 adults
- 2019
-
In: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:6, s. 2018-2025
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Subarachnoid haemorrhage (SAH) is a devastating disease, with high mortality rate and substantial disability among survivors. Its causes are poorly understood. We aimed to investigate risk factors for SAH using a novel nationwide cohort consortium.METHODS: We obtained individual participant data of 949 683 persons (330 334 women) between 25 and 90 years old, with no history of SAH at baseline, from 21 population-based cohorts. Outcomes were obtained from the Swedish Patient and Causes of Death Registries.RESULTS: During 13 704 959 person-years of follow-up, 2659 cases of first-ever fatal or non-fatal SAH occurred, with an age-standardized incidence rate of 9.0 [95% confidence interval (CI) (7.4-10.6)/100 000 person-years] in men and 13.8 [(11.4-16.2)/100 000 person-years] in women. The incidence rate increased exponentially with higher age. In multivariable-adjusted Poisson models, marked sex interactions for current smoking and body mass index (BMI) were observed. Current smoking conferred a rate ratio (RR) of 2.24 (95% CI 1.95-2.57) in women and 1.62 (1.47-1.79) in men. One standard deviation higher BMI was associated with an RR of 0.86 (0.81-0.92) in women and 1.02 (0.96-1.08) in men. Higher blood pressure and lower education level were also associated with higher risk of SAH.CONCLUSIONS: The risk of SAH is 45% higher in women than in men, with substantial sex differences in risk factor strengths. In particular, a markedly stronger adverse effect of smoking in women may motivate targeted public health initiatives.
|
|
| 10. |
- Wikman, Lars, 1981-
(author)
-
Don’t Mention the War : The forging of a domestic foreign policy consensus on the entry, expansion and exit of Swedish military contributions to Afghanistan
- 2021
-
Doctoral thesis (other academic/artistic)abstract
- Consensus is not something that just happens in the foreign policy domain when political actors seemingly agree on a policy. Rather, in this dissertation I demonstrate that actors construct consensus through the framing of policy as they highlight and downplay certain elements. Interestingly, for consensus to emerge, the attraction of political support is not always necessary; sometimes it is enough to not mobilize opposition. In the Swedish context a “foreign policy line” [utrikespolitisk linje] captures the prevailing consensus view and embraces a particular understanding of foreign policy in the national interest, historically conditioned and elevated above party politics. Based on archival records and 55 interviews, this dissertation explores and analyzes the political process in which a domestic foreign policy consensus was constructed for the entry, expansion and exit of the Swedish military contributions to Afghanistan in the early 2000s.Advocates and opponents frame their preferred policy with the intention of aligning it with a dominating perception of the continuity of Swedish foreign policy to gain wider acceptance. In the case of military contributions to Afghanistan, distancing themselves from sensitive issues such as the US warfare and framing policy so it resembled traditional Swedish foreign policy was a way for advocates to suppress political conflict within the political left and rally support behind the respective government's proposition. Afghanistan was a defining military operation at a pivotal time for Swedish foreign policy. The results therefore have wider implications for our understanding of the domestic politics of Swedish foreign policy, providing an important view of how a general reorientation following the Cold War was managed. In addition to conceptualizing the “foreign policy line” this study contributes theoretically with two frame alignment strategies, which actors employ when faced with an unfavorable context to avoid negative connotations.
|
|
