| 1. |
- Bader, Britt-Marie, 1960-
(författare)
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Att lyssna med hela kroppen : en studie om lärares ledarskap i utvecklingssamtal
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Keywords: Teachers´ leadership, parents-teachers ‘conference, primary school, didactic, hermeneutic, lifeworld phenomenologyThis thesis aims to explain what importance teachers´ leadership is given and how teachers' leadership appears in the parents-teacher conferences. The theoretical frame is lifeworld phenomenology, which means that the world is a social, intersubjective, and historical world where people experience, act, and intertwine in a private and a shared world. The study is inspired by a lifeworld approach and the data was analyzed to consider people's context, their experiences and the challenges involved in leading parent-teacher conferences. The empirical work is based on observations of parent-teacher conferences and interviews with teachers and students. The analyses are made with the support of the life-world phenomenological concepts of hållning, seeing-as and pedagogical tact. The concept hållning has a duality and loses its meaning in translation. Hållning means a bodily approach and is an intertwining between the teacher's attitude and her body posture. All three concepts include verbal and bodily communicative expressions and sensitive and intuitive actions, their meanings will be highlighted and explained. The results show that teachers' leadership in parent-teacher conferences includes both preparatory and subsequent work and forms part of the teaching. Leadership both shapes the parent-teacher conference and is shaped in the same and given importance when teachers show consideration for the student, the relationship between teacher and student and the situation, balance challenges with time and sensitive topics, choose to take notes in the parent-teacher conferences in favor of presence in the conversation itself and document afterwards. Teachers' leadership in parent-teacher conferences shape the conversation through teachers' willingness to involve the students, flexibility, and ability to structure. Teachers' leadership in parent-teacher conferences are shaped by teachers' responsiveness, compliance, presence, attention, ability to improvise and playfulness.The study's life-world phenomenological approach has made it possible to see that the parent-teacher conference requires a didactic knowledge related to the student as a person, to the content and to the structure that surrounds the conversation. This has been made visible in teachers' intuitive actions and bodily expressions as well as unreflected and reflected experiences. The study's starting points have made it possible to broaden the didactic understanding of the teachers' leadership in parent-teacher conferences by highlighting the clear intertwining of these conferences with other teaching
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| 2. |
- Bergman, Peder, et al.
(författare)
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Radial Variation of Measured Carrier Lifetimes in Epitaxial Layers Grown with Wafer Rotation
- 2012
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Ingår i: Materials Science Forum Vols 717 - 720. - : Trans Tech Publications Inc.. ; , s. 289-292
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Konferensbidrag (refereegranskat)abstract
- In this report we present homoepitaxial growth of 4H-SiC on the Si-face of nominally on-axis substrates with diameter up to 100 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers. Also, local variations in carrier lifetime are different from standard off-cut epilayers. The properties of layers were studied with more focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneous surface morphology and different growth mechanisms.
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| 3. |
- Booker, Ian Don, et al.
(författare)
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Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC
- 2014
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 14:8, s. 4104-4110
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.
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| 4. |
- Booker, Ian Don, et al.
(författare)
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Oxidation-induced deep levels in n- and p-type 4H- and 6H-SiC and their influence on carrier lifetime
- 2016
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Ingår i: Physical Review Applied. - : American Physical Society. - 2331-7019. ; 6:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- We present a complete analysis of the electron- and hole-capture and -emission processes of the deep levels ON1, ON2a, and ON2b in 4H-SiC and their 6H-SiC counterparts OS1a and OS1b through OS3a and OS3b, which are produced by lifetime enhancement oxidation or implantation and annealing techniques. The modeling is based on a simultaneous numerical fitting of multiple high-resolution capacitance deep-level transient spectroscopy spectra measured with different filling-pulse lengths in n- and p-type material. All defects are found to be double-donor-type positive-U two-level defects with very small hole-capture cross sections, making them recombination centers of low efficiency, in accordance with minority-carrier-lifetime measurements. Their behavior as trapping and weak recombination centers, their large concentrations resulting from the lifetime enhancement oxidations, and their high thermal stability, however, make it advisable to minimize their presence in active regions of devices, for example, the base layer of bipolar junction transistors.
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| 5. |
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| 6. |
- Haller, Sven, et al.
(författare)
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Amyloid Load, Hippocampal Volume Loss, and Diffusion Tensor Imaging Changes in Early Phases of Brain Aging
- 2019
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Ingår i: Frontiers in Neuroscience. - : FRONTIERS MEDIA SA. - 1662-4548 .- 1662-453X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose Amyloid imaging, gray matter (GM) morphometry and diffusion tensor imaging (DTI) have all been used as predictive biomarkers in dementia. Our objective was to define the imaging profile of healthy elderly controls as a function of their cognitive trajectories and explore whether amyloid burden and white matter (WM) microstructure changes are associated with subtle decrement of neuropsychological performances in old age. Materials and Methods We performed a 4.5-year longitudinal study in 133 elderly individuals who underwent cognitive testing at inclusion and follow-up, amyloid PET, MRI including DTI sequences at inclusion, and APOE epsilon 4 genotyping. All cases were assessed using a continuous cognitive score (CCS) taking into account the global evolution of neuropsychological performances. Data processing included region of interest analysis of amyloid PET analysis, GM densities and tract-based spatial statistics (TBSS)-DTI. Regression models were built to explore the association between the CCS and imaging parameters controlling for significant demographic and clinical covariates. Results Amyloid uptake was not related to the cognitive outcome. In contrast, GM densities in bilateral hippocampus were associated with worst CCS at follow-up. In addition, radial and axial diffusivities in left hippocampus were negatively associated with CCS. Amyloid load was associated with decreased VBM and increased radial and axial diffusivity in the same area. These associations persisted when adjusting for gender and APOE4 genotype. Importantly, they were absent in amygdala and neocortical areas studied. Conclusion The progressive decrement of neuropsychological performances in normal aging is associated with volume loss and WM microstructure changes in hippocampus long before the emergence of clinically overt symptoms. Higher amyloid load in hippocampus is compatible with cognitive preservation in cases with better preservation of GM densities and WM microstructure in this area.
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| 7. |
- Haller, Sven, et al.
(författare)
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PET amyloid in normal aging : direct comparison of visual and automatic processing methods
- 2020
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Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of amyloid deposits is a critical step for the identification of Alzheimer disease (AD) signature in asymptomatic elders. Whether the different amyloid processing methods impacts on the quality of clinico-radiological correlations is still unclear. We directly compared in 155 elderly controls with extensive neuropsychological testing at baseline and 4.5 years follow-up three approaches: (i) operator-dependent standard visual reading, (ii) operator-independent automatic SUVR with four different reference regions, and (iii) novel operator and region of reference-independent automatic A beta-index. The coefficient of variance was used to examine inter-individual variability for each processing method. Using visually-established amyloid positivity as the gold standard, the area under the receiver operating characteristic curve (ROC) was computed. Linear regression models were used to assess the association between changes in continuous cognitive score and amyloid uptake values. In SUVR analyses, the coefficient of variance varied from 1.718 to 1.762 according to the area of reference and was of - 3.045 for the A beta-index method. Compared to the visual rating, A beta-index method showed the largest area under the ROC curve [0.9568 (95% CI 0.9252, 0.98833)]. The best cut-off score was of - 0.3359 with sensitivity and specificity values of 0.97 and 0.83, respectively. Only the A beta-index was related to more severe decrement of cognitive performances [regression coefficient: 9.103 (95% CI 1.148, 17.058)]. The A beta-index is considered as preferred option in asymptomatic elders, since it is operator-independent, avoids the selection of reference area, is closer to established visual scoring and correlates with the evolution of cognitive performances.
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| 8. |
- Han, Guang, et al.
(författare)
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Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization
- 2015
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 47, s. 376-383
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Tidskriftsartikel (refereegranskat)abstract
- Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 gm. An additional mesoporous titania top layer following the contour of the macropores, of 100-200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography.
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| 9. |
- Hassan, Jawad, et al.
(författare)
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Influence of Growth Mechanism on Carrier Lifetime in on-axis Homoepitaxial Layers of 4H-SiC
- 2012
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Ingår i: Materials Science Forum Vols 717 - 720. - : Trans Tech Publications Inc.. ; , s. 157-160
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Konferensbidrag (refereegranskat)abstract
- In this report we present homoepitaxial growth of 4H-SiC on Si-face, nominally on-axis substrates with diameters up to 76 mm in a hot-wall chemical vapor deposition reactor. A comparatively low carrier lifetime has been observed in these layers; local variations in carrier lifetime are different from standard epilayers on off-cut substrates. The properties of the layers were studied with focus on charge carrier lifetime and its correlation with starting growth conditions, inhomogeneities of surface morphology and different growth mechanisms.
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| 10. |
- Jarpestam, S., et al.
(författare)
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Post-cardiac arrest intensive care in Sweden: A survey of current clinical practice
- 2023
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Ingår i: Acta Anaesthesiologica Scandinavica. - 0001-5172 .- 1399-6576. ; 67:9, s. 1249-1255
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Tidskriftsartikel (refereegranskat)abstract
- Background: European guidelines recommend targeted temperature management (TTM) in post-cardiac arrest care. A large multicentre clinical trial, however, showed no difference in mortality and neurological outcome when comparing hypothermia to normothermia with early treatment of fever. The study results were valid given a strict protocol for the assessment of prognosis using defined neurological examinations. With the current range of recommended TTM temperatures, and applicable neurological examinations, procedures may differ between hospitals and the variation of clinical practice in Sweden is not known. Aim: The aim of this study was to investigate current practice in post-resuscitation care after cardiac arrest as to temperature targets and assessment of neurological prognosis in Swedish intensive care units (ICUs). Methods: A structured survey was conducted by telephone or e-mail in all Levels 2 and 3 (= 53) Swedish ICUs during the spring of 2022 with a secondary survey in April 2023. Results: Five units were not providing post-cardiac arrest care and were excluded. The response rate was 43/48 (90%) of the eligible units. Among the responding ICUs, normothermia (36-37.7 degrees C) was applied in all centres (2023). There was a detailed routine for the assessment of neurological prognosis in 38/43 (88%) ICUs. Neurological assessment was applied 72-96 h after return of spontaneous circulation in 32/38 (84%) units. Electroencephalogram and computed tomography and/or magnetic resonance imaging were the most common technical methods available. Conclusion: Swedish ICUs use normothermia including early treatment of fever in post-resuscitation care after cardiac arrest and almost all apply a detailed routine for the assessment of neurological prognosis. However, available methods for prognostic evaluation varies between hospitals.
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| 11. |
- Kallinger, B., et al.
(författare)
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Comparison of carrier lifetime measurements and mapping in 4H SIC using time resolved photoluminescence and μ-PCD
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - Stafa-Zurich, Switzerland : Trans Tech Publications. - 9783038350101 ; , s. 301-304
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime measurements and wafer mappings have been done on several different 4H SiC epiwafers to compare two different measurement techniques, time-resolved photoluminescence and microwave induced photoconductivity decay. The absolute values of the decay time differ by a factor of two, as expected from recombination and measurement theory. Variations within each wafer are comparable with the two techniques. Both techniques are shown to be sensitive to substrate quality and distribution of extended defects.
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| 12. |
- Lilja, Johan, 1978-, et al.
(författare)
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Exploring an ecosystemic and regenerative approach to quality management : towards new theory and practice for a living world
- 2023
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Konferensbidrag (refereegranskat)abstract
- Quality Management (QM) is currently facing a new landscape that makes the traditional emphasis on internal organizational excellence as well as many of the QM leadership control practices, increasingly insufficient. The purpose of this paper is to contribute to revitalizing and updating QM theory and practice for a living world by exploring an ecosystemic and regenerative approach. The paper presents initial results from a study of the phenomena of developing and improving together, across boundaries of organizations and actors, in two complex ecosystems. The results highlight four enablers and six wishes that could inform further exploration and future QM practice.
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| 13. |
- Lilja, Louise, 1985-
(författare)
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4H-SiC epitaxy investigating carrier lifetime and substrate off-axis dependence
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Silicon carbide (SiC) is a wide bandgap semiconductor with unique material properties making it useful for various device applications using high power, high frequency and high temperature. Compared to Si-based electronics, SiC based electronics have an improved energy efficiency. One of the most critical problems is to reduce this planets power consumption, where large improvements can be made enhancing the energy efficiency. Independent on how the electrical power is generated, power conversion is needed and about 10% of the electrical power is lost for every power conversion step using Si-based electronics. Since the efficiency is related to the performance of the semiconductor device, SiC can make contributions to the efficiency. Compared to Si, SiC has three times larger bandgap, about ten times higher breakdown electric field strength and about three times higher thermal conductivity. The wide bandgap together with the chemical stability of SiC makes it possible for SiC electronic devices to operate at much higher temperatures (>250°C) compared to Si-based devices and do not require large cooling units as with Si power converters.The current status for 4H-SiC devices regard unipolar devices (≤ 1700 V), such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and Schottky barrier diodes (SBDs), are now on the market for mass production. The research focus is now on high-voltage (>10 kV) bipolar devices, such as, bipolar junction transistors (BJTs), p‑i‑n diodes and insulated-gate bipolar transistors (IGBTs).The focus of this thesis are material improvements relevant for the development of 4H-SiC high-voltage bipolar devices. A key parameter for such devices is the minority carrier lifetime, where long carrier lifetimes reduce the on-resistance through conductivity modulation. However, too long carrier lifetimes give long reverse recovery times leading to large switching losses. Thus, a tailored carrier lifetime is needed for the specific application. Carrier lifetimes of the epilayers can both be controlled by the CVD growth conditions and by post-growth processing, such as thermal oxidation and carbon implantation followed by thermal annealing. Emphasis in this thesis (Paper 1‑2) is to find optimal CVD growth conditions (growth temperature, C/Si ratio, growth rate, doping) improving the carrier lifetime. Since the main lifetime limiting defect has shown to be the Z1/2 center, identified as isolated carbon vacancies, growth conditions minimizing the Z1/2 concentration are strived for.To achieve high-voltage bipolar devices, thick epilayers of high quality is needed. An important factor is then the growth rate that needs to be relatively high in order to reduce the fabrication time, and thus the cost of the final device. In this thesis the growth process has been optimized for high growth rates (30 µm/h) using standard silane and propane chemistry (Paper 3), compared to other chemistries that includes chlorine, which results in corroded reactor parts and new defects in the epitaxial layers.Another important parameter for 4H-SiC bipolar devices is the basal plane dislocations (BPDs) in the substrate and epilayers, since the BPDs can act as source of nucleation and expansion of Shockley stacking faults (SSFs). The expanded SSFs give a lowered carrier lifetime and form a potential barrier for carrier transport leading to an increased forward voltage drop which in turn leads to bipolar degradation. The bipolar degradation is detrimental for 4H-SiC bipolar devices. Several strategies are developed to reduce the density of BPDs including buffer layers, growth interrupts and decreasing the substrates off-cut angle. Paper 4‑6 is focused on developing a CVD growth process for low substrate off-cut angles (1° and 2°) compared to the today’s standard off-cut angle of 4°. By reducing the substrate off-cut angle the number of BPDs intersecting the substrate surface is reduced. In addition, the conversion from BPDs to threading edge dislocations (TEDs) during epitaxial growth is increased with lower off-cut angles.
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| 14. |
- Lilja, Louise, et al.
(författare)
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Improved Epilayer Surface Morphology on 2 degrees off-cut 4H-SiC Substrates
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. ; , s. 206-209
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Konferensbidrag (refereegranskat)abstract
- Homoepitaxial layers of 4H-SiC were grown with horizontal hot-wall CVD on 2 degrees off-cut substrates, with the purpose of improving the surface morphology of the epilayers and reducing the density of surface morphological defects. In-situ etching conditions in either pure hydrogen or in a mixture of silane and hydrogen prior to the growth were compared as well as C/Si ratios in the range 0.8 to 1.0 during growth. The smoothest epilayer surface, together with lowest defect density, was achieved with growth at a C/Si ratio of 0.9 after an in-situ etching in pure hydrogen atmosphere.
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| 15. |
- Lilja, Louise, et al.
(författare)
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In-grown stacking-faults in 4H-SiC epilayers grown on 2 degrees off-cut substrates
- 2015
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Ingår i: Physica status solidi. B, Basic research. - : WILEY-V C H VERLAG GMBH. - 0370-1972 .- 1521-3951. ; 252:6, s. 1319-1324
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC epilayers were grown on 2 degrees off-cut substrates using standard silane/propane chemistry, with the aim of characterizing in-grown stacking faults. The stacking faults were analyzed with low temperature photoluminescence spectroscopy, room temperature photoluminescence mappings, room temperature cathodoluminescence and synchrotron white beam X-ray topography. At least three different types of in-grown stacking faults were observed, including double Shockley stacking faults, triple Shockley stacking faults and bar-shaped stacking faults. Those stacking faults are all previously found in 4 degrees and 8 degrees off-cut epilayers; however, the geometrical size is larger in epilayers grown on 2 degrees off-cut substrates due to lower off-cut angle. The stacking faults were formed close to the epilayer/substrate interface during the epitaxial growth. (C) 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim
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| 16. |
- Lilja, Louise, et al.
(författare)
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Influence of Growth Temperature on Carrier Lifetime in 4H-SiC Epilayers
- 2013
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime and formation of defects have been investigated as a function of growth temperature in n-type 4H-SiC epitaxial layers, grown by horizontal hot-wall CVD. Emphasis has been put on having fixed conditions except for the growth temperature, hence growth rate, doping and epilayer thickness were constant in all epilayers independent of growth temperature. An increasing growth temperature gave higher Z1/2 concentrations along with decreasing carrier lifetime. A correlation between growth temperature and D1 defect was also observed.
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| 17. |
- Lilja, Louise, 1985-, et al.
(författare)
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Influence of n-Type Doping Levels on Carrier Lifetime in 4H-SiC Epitaxial Layers
- 2017
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Ingår i: Silicon Carbide and Related Materials 2016. - : Trans Tech Publications Ltd. ; , s. 238-241
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Konferensbidrag (refereegranskat)abstract
- In this study we have grown thick 4H-SiC epitaxial layers with different n-type doping levels in the range 1E15 cm-3 to mid 1E18 cm-3, in order to investigate the influence on carrier lifetime. The epilayers were grown with identical growth conditions except the doping level on comparable substrates, in order to minimize the influence of other parameters than the n-type doping level. We have found a drastic decrease in carrier lifetime with increasing n-type doping level. Epilayers were further characterized with low temperature photoluminescence and deep level transient spectroscopy.
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| 18. |
- Lilja, Louise, 1985-, et al.
(författare)
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Smooth 4H-SiC epilayers grown with high growth rates with silane/propane chemistry using 4° off-cut substrates
- 2016
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Ingår i: Silicon Carbide and Related Materials 2015. - : Trans Tech Publications. ; , s. 209-212
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Konferensbidrag (refereegranskat)abstract
- 4H-SiC epilayers with very smooth surfaces were grown with high growth rates on 4° off-cut substrates using standard silane/propane chemistry. Specular surfaces with RMS values below 0.2 nm are presented for epilayers grown with growth rates up to 30 μm/h using horizontal hot-wall chemical vapor deposition, with up to 100 μm thickness. Optimization of in-situ etching conditions and C/Si ratio are presented.
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| 19. |
- Lilja, Linus, et al.
(författare)
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Target temperature 34 vs. 36°C after out-of-hospital cardiac arrest - a retrospective observational study.
- 2017
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Ingår i: Acta anaesthesiologica Scandinavica. - : Wiley. - 1399-6576 .- 0001-5172. ; 61:9, s. 1176-1183
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Tidskriftsartikel (refereegranskat)abstract
- Intensive care for comatose survivors of cardiac arrest includes targeted temperature management (TTM) to attenuate cerebral reperfusion injury. A recent multi-center clinical trial did not show any difference in mortality or neurological outcome between TTM targeting 33°C or 36°C after out-of-hospital-cardiac-arrest (OHCA). In our institution, the TTM target was changed accordingly from 34 to 36°C. The aim of this retrospective study was to analyze if this change had affected patient outcome.Intensive care registry and medical record data from 79 adult patients treated for OHCA with TTM during 2010 (n=38; 34°C) and 2014 (n=41; 36°C) were analyzed for mortality and neurological outcome were assessed as cerebral performance category. Student's t-test was used for continuous data and Fischer's exact test for categorical data, and multivariable logistic regression was applied to detect influence from patient factors differing between the groups.Witnessed arrest was more common in 2010 (95%) vs. 2014 (76%) (P=0.03) and coronary angiography was more common in 2014 (95%) vs. 2010 (76%) (P=0.02). The number of patients awakening later than 72h after the arrest did not differ. After adjusting for gender, hypertension, and witnessed arrest, neither 1-year mortality (P=0.77), nor 1-year good neurological outcome (P=0.85) differed between the groups.Our results, showing no difference between TTM at 34°C and TTM at 36°C as to mortality or neurological outcome after OHCA, are in line with the previous TTM-trial results, supporting the use of either target temperature in our institution.
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| 20. |
- Lilja, Louise, et al.
(författare)
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The Effect of Growth Conditions on Carrier Lifetime in n-type 4H-SiC Epitaxial Layers
- 2012
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Ingår i: Materials Science Forum Vol 717 - 720. - : Trans Tech Publications Inc.. ; , s. 161-164
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Konferensbidrag (refereegranskat)abstract
- Carrier lifetime has been studied as a function of C/Si ratio and growth rate during epitaxial growth of n-type 4H-SiC using horizontal hot-wall CVD. Effort has been put on keeping all growth parameters constant with the exception of the parameter that is intended to vary. The carrier lifetime is found to decrease with increasing growth rate and the highest carrier lifetime is found for a C/Si ratio of 1. The surface roughness was correlated with epitaxial growth conditions with AFM analysis.
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| 21. |
- Lilja, Louise, et al.
(författare)
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The influence of growth conditions on carrier lifetime in 4H-SiC epilayers
- 2013
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Ingår i: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 381, s. 43-50
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC homoepitaxial layers have been grown in a horizontal hot-wall CVD (chemical vapor deposition) reactor and the measured carrier lifetimes have been correlated to the CVD growth conditions. Two different generations of reactors were compared, resulting in measured carrier lifetimes in two different orders of magnitude, from a few hundreds of ns to a few ms. The variations in measured carrier lifetime were correlated to deep level concentrations of the Z(1/2) center and the D-1 center, seen by photoluminescence. Decreasing the growth temperature clearly prolonged the carrier life time and showed lower Z(1/2) concentrations, where as lowering the growth rate only showed a small improvement of the carrier lifetime and no obvious tendencyin Z(1/2) defect concentrations, indicating that Z(1/2) is not the only defect limiting the carrier lifetime. Increasing the C/Si ratio resulted in decreasing Z(1/2) concentrations, indicating the carbon vacancy nature of the defect. However, carrier lifetime measurements showed maximum values for a C/Si ratio of 1 but otherwise an increasing tendency for increasing C/Si ratios. The reactor giving higher carrier lifetimes, correspondingly also showed lower Z(1/2) concentrations indicating the lifetime limiting property of Z(1/2). Furthermore, the D-1 defect intensity increased with growth temperature and decreased with increasing C/Si ratio, similar to the Z(1/2) concentration.
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| 22. |
- Lilja, Margareta, et al.
(författare)
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Attitudes towards rehabilitation needs and support from assistive technology and the social environment among elderly people with disability
- 2003
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Ingår i: Occupational Therapy International. - : Wiley. - 0966-7903 .- 1557-0703. ; 10:1, s. 75-93
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to survey the attitudes of elderly people with disabilities who were living at home regarding their support from assistive technology and the social environment. These attitudes were compared with their identified needs by an occupational therapist and in relation to perception of social engagement, loneliness and overall contentment with life. From a sample of 102 participants who were interviewed using a standardized procedure, 53 persons were included in the study. The results indicated that attitudes among elderly people towards social and occupational engagement and change have a greater influence on their rehabilitation status than their disability as indicated by their health condition and limitations in activities of daily living and instrumental activities of daily living. The elderly people who accepted rehabilitation were more able, and were better equipped and better supported with assistive technology, than those who declined rehabilitation. Rehabilitation needs that the occupational therapists recognized were not always shared by the disabled elderly people, for several reasons; one reason of particular importance was the elderly person's attitude towards change and social engagement. However, the small sample size limits the generalization of the findings to the population of elderly people with disabilities. An ethnographic research design that allows for repeated interviews and observations of elderly people with disabilities for a prolonged period of time in their ordinary everyday lives may present an avenue for future research and lead to a deeper understanding of the issues
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| 23. |
- Lilja, Margareta, et al.
(författare)
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The transfer of information about geriatric clients in the occupational therapy chain of care : An intervention study
- 2000
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Informa UK Limited. - 1103-8128 .- 1651-2014. ; 7:2, s. 51-59
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Tidskriftsartikel (refereegranskat)abstract
- Continuity of interventions for elderly persons after discharge from hospital is affected by the communication between professionals involved in the rehabilitation process. This study describes an intervention project that was implemented to improve ways of transferring information relating to geriatric clients between occupational therapists working on different organizational levels. An assessment of activities of daily living (the ADL taxonomy) was used as a uniform instrument of communication. The results revealed that aspects of temporality, structure, professionalism and the instrument's usefulness influenced the transfer of information. Systematic discharge planning schemes, written and formally structured information, a feedback loop for communication, and collaboration with the clients and their families in the discharge process are all suggested as ways of transferring information.
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| 24. |
- Lööv, Anna, 1990-, et al.
(författare)
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Diagnostic accuracy for colorectal cancer of a quantitative faecal immunochemical test in symptomatic primary care patients : a study protocol
- 2022
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Ingår i: Diagnostic and prognostic research. - : BioMed Central (BMC). - 2397-7523. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There is increasing evidence supporting the use of faecal immunochemical tests (FIT) in patients reporting symptoms associated with colorectal cancer (CRC), but most studies until now have focused on selected subjects already referred for investigation. We therefore set out to determine the accuracy and predictive values of FIT in a primary care population.METHOD: A prospective, multicentre, single-gated comparative diagnostic study on quantitative FIT in patients aged 40 years and above presenting in primary care with symptoms associated with CRC will be conducted. Patients representing the whole spectrum of severity of such symptoms met with in primary care will be eligible and identified by GPs. Participants will answer a short form on symptoms during the last month. They will provide two faecal samples from two separate days. Analyses will be performed within 5 days (QuikRead go®, Aidian Oy). The analytical working range is 10-200 μg Hb/g faeces. Reference test will be linked to the Swedish Colorectal Cancer Registry up to 2 years after inclusion. Accuracy, area under ROC curves, and predictive values will be calculated for one FIT compared to the highest value of two FIT and at cutoff < 10, 10-14.9, 15-19.9 and ≥ 20 μg Hb/g faeces. Subgroup analyses will be conducted for patients with anaemia and those reporting rectal bleeding. A model-based cost-effectiveness analysis based on the clinical accuracy study will be performed. Based on previous literature, we hypothesized that the sensitivity of the highest value of two FIT at cutoff 10 μg Hb/g faeces will be 95% (95% CI + / - 15%). The prevalence of CRC in the study population was estimated to be 2%, and the rate of non-responders to be 1/6. In all, 3000 patients will be invited at 30 primary care centres.DISCUSSION: This study will generate important clinical real-life structured data on accuracy and predictive values of FIT in the most critical population for work-up of CRC, i.e. patients presenting with at times ambiguous symptoms in primary care. It will help establish the role of FIT in this large group.
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| 25. |
- Nygård, Louise, et al.
(författare)
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The provision of stove timers to individuals with cognitive impairment
- 2008
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Informa UK Limited. - 1103-8128 .- 1651-2014. ; 15:1, s. 4-12
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify the characteristics of persons who were provided with timing devices on stoves, and to investigate the application procedure and recommendations for timer options. The case files at an Agency for Home Modifications in an urban community in Sweden during 2002 (n = 945) were audited. The sample was divided into two groups: those diagnosed or suspected of dementia or age-related memory deficits (n = 788), and those with other diagnoses (n = 151). Overall, the applicants for stove timers were elderly females, living alone. Assistance with the application forms by health professionals was common in both groups. However, the options available for tailoring the use of the device were not used consistently and the opportunity for professional follow-up appeared limited. The device seemed to be used as a safety precaution rather than as a device to support independent activity performance based on individual users' needs. The results indicate that improvements in the implementation and provision of stove timers could be achieved through education and collaboration between different stakeholders.
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| 26. |
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| 27. |
- Snyder, Kristen, 1964-, et al.
(författare)
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Reimagining research on organisations as living systems through participatory and arts-based practices : Insights from the field
- 2023
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Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to explore the use of participatory practices as a research methodology based on a reflexive analytical method. Examples will be derived from applying design thinking, storytelling and appreciative inquiry in a partnership project with three businesses. Two questions drive the reflexive analysis: How can participatory practice be applied as an empirical method that serves both data collection and organizational development? What can we learn from the application of storytelling, appreciative inquiry and design thinking to inform the development of research methods as part of the interactive design approach? This analysis contributes to the development of interactive research design as an approach to studying organizations in the VUCA landscape and the emergence paradigm in quality.Reimagining research methods in organisations as living organisms is conceptualized at the intersection between science and practice and contributes to the ongoing discussion about the use of interactive design (Ellström et al., 2020; Johnson & Wallo, 2020) generative scholarship (Pavez et al., 2021) as an applied-based research methodology.
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| 28. |
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| 29. |
- Ul-Hassan, Jawad, et al.
(författare)
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Fast growth rate epitaxy on 4((degrees)under-bar) off-cut 4-inch diameter 4H-SiC wafers
- 2014
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2013, PTS 1 AND 2. - : Trans Tech Publications. ; , s. 179-182
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Konferensbidrag (refereegranskat)abstract
- We report the development of over 100 mu m/h growth rate process on 4-inch diameter wafers using chlorinated growth. The optimized growth process has shown extremely smooth epilayers completely free of surface step-bunching with very low surface defect density, high uniformity in thickness and doping and high run to run reproducibility in growth rate, controlled doping and defect density.
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| 30. |
- ul Hassan, Jawad, et al.
(författare)
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On-axis homoepitaxial growth of 4H-SiC PiN structure for high power applications
- 2013
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Ingår i: Silicon Carbide and Related Materials 2012. - : Trans Tech Publications Inc.. - 9783037856246 ; 740-742, s. 173-176, s. 173-176
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Konferensbidrag (refereegranskat)abstract
- We demonstrate on-axis homoepitaxial growth of 4H-SiC(0001) PiN structure on 3-inch wafers with 100% 4H polytype in the epilayer excluding the edges. The layers were grown with a thickness of 105 μm and controlled n-type doping of 4 x 1014 cm-3.The epilayers were completely free of basal plane dislocations, in-grown stacking faults and other epitaxial defects, as required for 10 kV high power bipolar devices. Some part of the wafer had a lifetime enhancement procedure to increase lifetime to above 2 μs using carbon implantation. An additional step of epilayer polishing was adapted to reduce surface roughness and implantation damage.
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| 31. |
- Ul-Hassan, Jawad, et al.
(författare)
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Wafer Scale On-Axis Homoepitaxial Growth of 4H-SiC(0001) for High-Power Devices: Influence of Different Gas Phase Chemistries and Growth Rate Limitations
- 2019
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 19:6, s. 3288-3297
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Tidskriftsartikel (refereegranskat)abstract
- On-axis homoepitaxy of 4H-SiC has the advantage of producing epilayers that are free of basal plane dislocations. Such layers can be highly beneficial for SiC-based high-power bipolar electronic devices which otherwise suffer from bipolar degradation phenomena related to basal plane dislocations in epilayers. In this study, we have developed on-axis homoepitaxy on the Si-face of 100 mm diameter 4H-SiC wafers with only 4H polytype in the epilayer excluding the edges of the wafer. We have also compared standard and chloride-based growth, the influence of different ambient conditions on surface preparation of the substrate, the influence of the histories of different growth cells, and the geometry of the susceptors regarding 4H-polytype stability in the epilayer. Substrate surface preparation, growth temperature, C/Si ratio, and Si/H ratio are found to be the most influential parameters to achieve homoepitaxy. On-axis homoepitaxial growth rate is limited to a very low value of amp;lt;10 mu m/h. We have performed a systematic study to understand the influence of different growth parameters and gas phase chemistries to determine whether on-axis growth rate can be enhanced and, if not, what the limiting factors are. Our experimental evidence suggests that the on-axis growth rate is not limited by the gas phase chemistry or diffusion, but it is limited by the surface kinetics. A significantly low step density on on-axis substrates lowers the surface reaction rates and limits the growth rate to lower values. It may not be possible to further improve the growth rate even with chloride-based growth using epitaxial growth conditions.
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| 32. |
- Vik, Kjersti, et al.
(författare)
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Encountering staff in the home : Three older adults' experience during six months of home-based rehabilitation
- 2009
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Ingår i: Disability and Rehabilitation. - : Informa UK Limited. - 0963-8288 .- 1464-5165. ; 31:8, s. 619-629
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. The purpose of the present study was to explore and describe how older adults who received home-based rehabilitation perceived the staff during a period of 6 months when they received rehabilitation. Specifically, the study focused on how the participants collaborated with and made use of the services from the staff. Method. In this case-oriented study, three older adults were interviewed continuously during the 6-month period they received home-based rehabilitation. The interviews were analysed continuously using a grounded theory approach. Results. Five different modes of perceiving the staff were identified among the participants: as small talk persons, as discussions partners, as instructors and advisors, as teachers and as persons who carry out tasks efficiently. The three conditions that most came to influence the way the participants perceived collaborated with the staff were as follows: 'experience and encounters with the staff', 'expectations for the future daily life', and 'the participants' needs and tasks related to their disability'. Conclusions. To achieve collaboration and user involvement, the staffs have to encounter each client differently in accordance with the various tasks that must be carried out during rehabilitation. Our findings indicate that this is particularly important for older adults during home-based rehabilitation, since older adults often have changing needs because of comorbidity
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| 33. |
- Vik, Kjersti, et al.
(författare)
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Perceived environmental influence on participation among older adults after home-based rehabilitation
- 2007
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Ingår i: Physical & Occupational Therapy in Geriatrics. - 0270-3181 .- 1541-3152. ; 25:4, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify how older adults perceive environmental factors to have an influence on their participation after receiving home-based rehabilitation services. The respondents were older adults of more than 65 years of age who had received home-based rehabilitation. The questionnaire Measurement of the Quality of the Environment (MQE) was used to gather the data. The results showed that, in this population of older adults, many environmental factors were perceived as do not apply or to lack influence. Factors that were perceived as facilitators for the respondent's participation came under the categories social network, social and healthcare services and commercial services, and physical environments such as the presence of technical aids within the respondents' homes. Few environmental factors were identified as barriers to participation
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| 34. |
- Vik, Kjersti, et al.
(författare)
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The influence of the environment on participation subsequent to rehabilitation as experienced by elderly people in Norway
- 2007
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Informa UK Limited. - 1103-8128 .- 1651-2014. ; 14:2, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to illuminate how the environment may influence participation among elderly people who have undergone community-based rehabilitation in Norway, after an acute illness or accident. Fourteen persons over 65 years of age were selected with the specific intention of gaining a variety of ages, both genders, and people living in different kinds of housing. Three focus groups were established and repeated interviews were held with each group. A constant comparative analysis was used to analyse the data. The main finding was that the participants experienced pressure from their environment to concentrate on performing the most necessary daily activities rather than on participation. Three main encounters with environments seemed to be important for this: encountering people and society, encountering private and formal assistance, and encountering occupation. The support that the participants received from family and friends was more important for their participation than having accessible physical environments. The findings suggest that occupational therapists must consider themselves to be part of a societal environment that can hinder participation.
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