| 1. |
- Abdu, Yassir Ahmed Mohamed, 1966-
(författare)
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Mössbauer Spectroscopy of Meteoritic and Synthetic Fe-Ni Alloys
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis reports on the results of investigating Fe-containing minerals in meteorites, with focus on Fe-Ni minerals and their magnetic properties, along with some synthetic Fe-Ni analogues. The New Halfa meteorite, which fell in Sudan 1994, has been studied using Mössbauer spectroscopy, X-ray diffraction, and electron microprobe analysis techniques, and classified as an ordinary L-type chondrite of petrologic type 4. Mössbauer spectra of taenite-enriched samples from the metal particles of the New Halfa (L4) and Al Kidirate (H6) meteorites identify the following γ (fcc) Fe-Ni phases: the ferromagnetic atomically ordered taenite (tetrataenite) with ~ 50 at % Ni, the ferromagnetic disordered taenite with ~ 50 at % Ni, the low-Ni (~ 25 at %) paramagnetic taenite (antitaenite). The presence of the superstructure of tetrataenite is confirmed by synchrotron X-ray diffraction.Fe-rich γ (fcc) Fe-Ni alloys with compositions Fe79Ni21, Fe76Ni24, and Fe73Ni27, which serve as synthetic analogues of antitaenite, are prepared by mechanical alloying and subsequent annealing at 650 °C. The Mössbauer results indicate that these alloys are inhomogeneous and contain a high moment (HM) ferromagnetic Ni-rich phase (> 30 at % Ni) and a low moment (LM) paramagnetic Fe-rich phase, which orders antiferromagnetically at low temperature. The coexistence of these phases is attributed to phase segregation occurring on short range, probably nanometer scale, consistent with the Fe-Ni phase diagram below 400 °C where there is a miscibility gap associated with a spinodal decomposition in alloys with < 50 at % Ni.The combined high field Mössbauer spectroscopy and SQUID magnetometry results on these alloys at room temperature indicate large induced local magnetic moments in the paramagnetic part of the sample, which increases with increasing the Ni content. The results, when compared with the high field Mössbauer results on antitaenite from the metal particle of Al Kidirate and New Halfa meteorites may be used to estimate the Ni content of antitaenite in meteorites.High pressure 57Fe Mössbauer spectroscopy measurements up to ~ 41 GPa have been carried out at room temperature using the diamond anvil cell (DAC) technique in order to investigate the magnetic properties of γ (fcc) 57Fe53Ni47 alloy. The results indicate a pressure induced Invar effect at ~ 7 GPa and a non-magnetic or paramagnetic state above 20 GPa, demonstrating the volume dependence of the magnetic moment of γ (fcc) Fe-Ni alloys.
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| 2. |
- Abrahamsson, Gun, 1961-, et al.
(författare)
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Problemlösningsarbete på låg organisatorisk nivå : Två studier om implementering respektive konkretisering av idéer om kundorderstyrd tillverkning
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The two studies reported in this thesis are about problem solving at a low organisational level in an organisational unit in a Swedish manufacturing company, which has adopted ideas of World Class Manufacturing. In the first study, we analyse, from an organisational learning perspective, the implementation of the well-known concept Continuous Improvement at shop-floor level and how management accounting may facilitate or impede improvement work. A case study was conducted in two workgroups in one production unit for about seven months. In one of the groups, management accounting facilitated improvement work with high organisational scope and, in the other group, impeded the organisational scope. Our conclusion is that management accounting may facilitate a high organisational scope by supporting the leadership style, stressing co-operation, dialog and participation, or, by the way the manager uses management accounting, make boundaries distinct between groups of employees and between departments, and therefore impede improvements with high organisational scope. In the second study, we analyse, from a rule-based behavioural perspective, how ideas of World Class Manufacturing are institutionalised in cross-functional problem solving at a low organisational level. A case study was carried out in two cross-functional weekly group meetings for about nine months. Problems raised and solutions decided followed a repeated pattern. The actors draw on instrumental rules, which can be described as technical as well as economic. We concluded that ideas of World Class Manufacturing were institutionalised as different variants of World Class Manufacturing in the different functions at a low organisational level. At the meetings, contradictory instrumental rules were activated by the functions and treated according to interaction rules. Two overall patterns of action, articulated the two main interaction rules guiding actors in how to treat contradictory ideas of World Class Manufacturing.
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| 3. |
- Acosta, Stefan, 1967-
(författare)
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On Acute Thrombo-Embolic Occlusion of the Superior Mesenteric Artery
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Acute thrombo-embolic occlusion of the superior mesenteric artery (SMA) with intestinal infarction is a lethal disease, difficult to diagnose in time, with unknown incidence and cause-specific mortality. The aim of this thesis was to characterize the disease and to develop diagnostic methods. Two laboratory studies were conducted on patients with suspected acute SMA occlusion. A pilot-study showed that the fibrinolytic marker D-dimer was elevated in six patients with the disease. In the subsequent study including 101 patients, D-dimer was the only elevated coagulation marker in nine patients with the disease. In a prospective study 24 patients (median age 84 years) were identified, of whom four were diagnosed at autopsy, despite an autopsy-rate of 10%. One-fourth were initially nursed in non-surgical wards. Length of the intestinal infarction was a predictor for death. An analysis of patients from the three studies showed that D-Dimer was elevated in all 16 tested patients with the disease.Sixty patients with acute SMA occlusion underwent intestinal revascularisation and were registered in the Swedish Vascular Registry (SWEDVASC). One-year survival-rate was 40%. Previous vascular surgery was a negative risk-factor.A population-based study was conducted in Malmö, based on an autopsy-rate of 87%. Among 270 patients with the disease, 2/3 were diagnosed only at autopsy and 1/2 were managed in non-surgical wards. The incidence was 8.6 per 100000 person years. The age-standardized incidence increased exponentially without gender differences. The diagnosis was the cause of death in 1.2% among octogenarians and beyond. Thrombotic occlusions were located proximally within the SMA and associated with extensive intestinal infarctions. Synchronous embolism, often multiple, occurred in 2/3 of the patients with embolic occlusions.Conclusions: A normal D-dimer at presentation most likely excludes the diagnosis. Acute SMA occlusion was more frequent than previously estimated from clinical series. The patients were often nursed in non-surgical wards.
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| 4. |
- Adamiak, Grazyna Teresa, 1956-
(författare)
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Påverkan av organisatoriska och miljömässiga faktorer på tillgänglighet till akutsjukvården
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The settings investigated were departments of internal medicine (IM), orthopaedics and surgery in acute care hospitals in Sweden. The objective was to identify exogenous and endogenous determinants of accessibility of health care. Both qualitative and quantitative analysis of utilisation was performed on national and regional level of data aggregation. The study proposes that accessibility to acute health services is influenced by exogenous factors, partly outside the control of health care professionals, such as season, physical proximity and overall supply. Organisational properties such as availability of inpatient beds, hospital and physician specialisation and the degree of system integration between provides of emergency care have effects on the quality of care. The novel finding is the strong association between acute readmissions and remaining inpatient utilisation indicating effects of bed supply on global use within IM. These conclusions follow:§ structural changes on system level work as a method of prioritisation between patient groups by changes in criteria of accessibility;§ the natural and organisational environments determine waiting times in EDs in hospitals by fluctuations of demand;§ geographical accessibility coincides with the supply in terms of over- or underutilisation mirrored in the outcome of medical care;§ effective access is determined by the divide of resources between inpatient and outpatient care and the total supply of inpatient care;§ increasing demands on inpatient care in IM may be derived from deficiencies in the care of chronically ill, elderly patients;§ transition of information and communication among care givers and patients varies in efficiency depending on vehicles for coordination and system integration;§ the level of training of the admitting physician has effects on effective accessibility to inpatient care.There are conflicts between accessibility, efficiency and appropriateness of settings calling for attention to capacity to benefit in addition to needs as priority criteria.
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| 5. |
- Adman, Per, 1970-
(författare)
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Arbetslöshet, arbetsplatsdemokrati och politiskt deltagande
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis is to test two hypotheses about how work affects political participation. The first concerns unemployment, and states that unemployment has strong and negative effects on political activity. The second hypothesis is found in theories of participatory democracy, and claims that more democratic workplaces lead to more political participation. Existing empirical evidence on both of the hypotheses is not conclusive. Furthermore, studies have mainly been carried out using data collected in the United States. Here empirical tests of the hypotheses are undertaken using a Swedish survey.The results confirm the first hypothesis; unemployment has negative effects on political participation. The reasons for these negative effects are that the unemployed become less active in organisational life, fall outside of the recruitment networks where people are being asked to participate in politics, and experience a decrease in income. The second hypothesis is not supported. Workplace participation does not affect political participation, according to the analyses. The results are surprising for both hypotheses, and contradict previous empirical findings. The differences in results are likely due to differences in research design and differences in approaches to analysing political participation. Previous studies are inadequate in these perspectives, it is maintained.The thesis ends with a discussion of the results from the perspective of normative democratic theory. It is argued that the lack of political equality is particularly acute when the low participation among the unemployed is considered.
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| 6. |
- Afzelius, Lovisa, 1975-
(författare)
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Computational Modelling of Structures and Ligands of CYP2C9
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- CYP2C9 is one of our major drug metabolising enzymes and belongs to the cytochrome P450 (CYP) super family. The aim of this thesis was to gain an understanding of the quantitative structure–activity relationships (QSAR) of CYP2C9 substrates and inhibitors. This information will be useful in predicting drug metabolism and the potential for drug–drug interactions. To achieve this, a well characterised data set of structurally diverse, competitive CYP2C9 inhibitors was identified in our laboratory. Several computational methodologies, many based on GRID molecular interaction fields, were applied or developed in order to handle issues such as compound alignment and bioactive conformer selection. First, a traditional 3D QSAR was carried out in GOLPE, generating a predictive model. In this model the selection of a bioactive conformer and alignment was based on docking in a homology model of CYP2C9. Secondly, we introduced the concept of alignment independent descriptors from ALMOND. These descriptors were used to generate quantitatively and qualitatively predictive models. We subsequently derived conformation independent descriptors from molecular interaction fields calculated in FlexGRID. This enabled the derivation of 3D QSAR models without taking into account the selection of an alignment or a bioactive conformer. A subsequent programming effort enabled the conversion of this model back to 3D aligned pharmacophores. Similar alignment independent descriptors were also used in the development of the software MetaSite® that predicts the site of metabolism for CYP2C9 ligands. Finally, as crystal information on this isoform emerged, the performance of molecular dynamics simulations and homology models and the flexibility of the protein were evaluated using statistical analyses.These modelling efforts have resulted in detailed knowledge of the structural characteristics in ligand interactions with the cytochrome P450 2C9 isoform.
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| 7. |
- Ahlin, Åsa, 1970-
(författare)
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Compulsory Schooling in a Decentralized Setting: Studies of the Swedish Case
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Essay 1 (with Eva Johansson) investigates the demand for local public schooling using survey data, a method previously never applied to Sweden. Estimating a demand specification corresponding to that in U.S. studies, more elastic demand than in the U.S. is found. In an alternative specification, a more inelastic demand is indicated, in line with earlier findings on demand for total local spending in Sweden. Support for the hypothesis that municipal employees tend to have higher preferences for local public school spending than other employees is found. The differences in elasticities are, however, not statistically significant.Essay 2 investigates school competition and its implications for student performance. Using a value added specification, increased local school competition is shown to have positive effects on average performance in mathematics, but no significant effects in English or Swedish test performance. Immigrant pupils and those in need of special education tend to gain more from increased school competition, while adverse effects on students from low education families are found in terms of English and Swedish performance. Quantile regressions indicate homogeneous effects on low and high performing students.Essay 3 (with Eva Mörk) investigates the extent to which grants, local tax base, preferences and structural characteristics affected local school resources in connection with the decentralization of compulsory schooling in Sweden, using municipal panel data covering 1989-1995. The main arguments against decentralization are not supported by our findings. First, school spending as well as teacher density is found to be more equally distributed across municipalities following decentralization. Second, local tax capacity is not found to influence local school resources more in the decentralized than in the centralized regime. Furthermore, targeted grants have a significant impact on resources while general grants have not.Essay 4 examines teacher mobility in Sweden. Particular attention is paid to the role of working conditions. Various school attributes are used to proxy for teachers’ working conditions, including the average student performance, school resources and student composition. The results indicate a link, in the expected direction, between school attributes and the probability that a teacher will leave her teaching position in favour of another school. Also, teachers with higher wages tend to have a lower propensity of leaving their school. In contrast to previous US findings, the estimated impact of wages are not sensitive to whether or not controls for school attributes are included.
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| 8. |
- Alfimov, Vasily, 1978-
(författare)
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Accelerator Mass Spectrometry of 36Cl and 129I : Analytical Aspects and Applications
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two long-lived halogen radionuclides (36Cl, T1/2 = 301 kyr, and 129I, T1/2 = 15.7 Myr) have been studied by means of Accelerator Mass Spectrometry (AMS) at the Uppsala Tandem Laboratory. The 36Cl measurements in natural samples using a medium-sized tandem accelerator (~1 MeV/amu) have been considered. A gas-filled magnetic spectrometer (GFM) was proposed for the separation of 36Cl from its isobar, 36S. Semi-empirical Monte-Carlo ion optical calculations were conducted to define optimal conditions for separating 36Cl and 36S. A 180° GFM was constructed and installed at the dedicated AMS beam line. 129I has been measured in waters from the Arctic and North Atlantic Oceans. Most of the 129I currently present in the Earth's surface environment can be traced back to liquid and gaseous releases from the nuclear reprocessing facilities at Sellafield (UK) and La Hague (France). The anthropogenic 129I inventory in the central Arctic Ocean was found to increase proportionally to the integrated 129I releases from these reprocessing facilities. The interaction and origin of water masses in the region have been clearly distinguished with the help of 129I labeling. Predictions based on a compartment model calculation showed that the Atlantic Ocean and deep Arctic Ocean are the major sinks for the reprocessed 129I. The variability in 129I concentration measured in seawater along a transect from the Baltic Sea to the North Atlantic suggests strong enrichment in the Skagerrak–Kattegat basin. The 129I inventory in the Baltic and Bothnian Seas is equal to ~0.3% of the total liquid releases from the reprocessing facilities. A lake sediment core sampled in northeastern Ireland was analyzed for 129I to study the history of the Sellafield releases, in particular the nuclear accident of 1957. High 129I concentration was observed corresponding to 1990 and later, while no indication of the accident was found. The results of this thesis research clearly demonstrate the uniqueness and future potential of 129I as a tracer of processes in both marine and continental archives.
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| 9. |
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| 10. |
- Alm, Jan, 1947-
(författare)
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Dyslexia: Relevance of Concepts, Validity of Measurements, and Cognitive Functions
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis opens with an exposition of different uses of the term dyslexia. In that context its conceptual relevance is discussed. The empirical studies investigate a) different aspects of validity of cognitive and achievement instruments often used in diagnostic assessment of dyslexia, b) different cognitive profiles for adults with dyslexia, and c) the relationship between cognitive and achievement measures.Study I demonstrated the factor structure of the Swedish WAIS-R to be in close agreement with results of comparable analyses on normal and clinical groups in many countries world-wide, giving strong support for the construct validity of the Swedish WAIS-R for a group of adults diagnosed with dyslexia. The results from the three-factor solution were interpreted in terms of theoretical constructs, notably those posited by Carroll (1993) and Horn (1989).The cognitive profiles of a sample of Swedish adults diagnosed with dyslexia—when using the three factors, the ACID profile, and the four-category Bannatyne profile—all resemble closely the profiles observed for a wide array of U.S. samples of children and adults diagnosed with dyslexia or learning disabilities. Gender differences on Digit Symbol, favoring females, were substantial in magnitude for the present sample, consistent with a bulk of research on gender differences for samples of normal individuals and of those identified with learning problems.In Study II, factor analysis of nine Swedish achievement tests often used for dyslexia assessment yielded five meaningful factors in a group of adults diagnosed with dyslexia. Factors appeared to measure decoding, visual speed, reading comprehension, reading fluency, and phonological ability. The relationship between the five achievement factors and WAIS-R variables was subsequently examined. The Visual Speed and Reading Comprehension factors each correlated significantly with four of six global WAIS-R scores (two of three IQs and two of three factor scores). Visual Speed tended to correlate significantly with nonverbal scores and Reading Comprehension with verbal scores. Although the Phonological Ability factor did not correlate significantly with any verbal or nonverbal global score, it did correlate significantly with the Freedom from Distractibility factor and with all its component subtests—Digit Span, Arithmetic, and Digit Symbol. Decoding (technical reading skill) showed no significant relationship to any WAIS-R variable studied. More surprisingly, the Reading Fluency factor failed to show significant relationships to the WAIS-R.Study III examined the validity of The Word Chain Test, a frequently used instrument in Swedish screening and diagnostic assessments of dyslexia. Different sources of validity evidence were evaluated. In summary, the results failed to support validity both for the WRI-index and the Wordchain subtest, suggesting that the instrument seems to be of questionable value in screening or diagnostic assessment of dyslexia.
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