| 1. |
- Aarao, J, et al.
(författare)
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Numerical implementation of the EDEM for modified Helmholtz BVPs on annular domains
- 2011
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Ingår i: JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS. - : Elsevier Science B.V., Amsterdam.. - 0377-0427. ; 235:5, s. 1342-1353
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Tidskriftsartikel (refereegranskat)abstract
- In a recent paper by the current authors a new methodology called the Extended-Domain-Eigenfunction-Method (EDEM) was proposed for solving elliptic boundary value problems on annular-like domains. In this paper we present and investigate one possible numerical algorithm to implement the EDEM. This algorithm is used to solve modified Helmholtz BVPs on annular-like domains. Two examples of annular-like domains are studied. The results and performance are compared with those of the well-known boundary element method (BEM). The high accuracy of the EDEM solutions and the superior efficiency of the EDEM over the BEM, make EDEM an excellent alternate candidate to use in the animation industry, where speed is a predominant requirement, and by the scientific community where accuracy is the paramount objective.
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| 2. |
- Aarnio, Harri, et al.
(författare)
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Spontaneous Charge Transfer and Dipole Formation at the Interface Between P3HT and PCBM
- 2011
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Ingår i: Advanced Energy Materials. - : Wiley-VCH Verlag Berlin. - 1614-6832 .- 1614-6840. ; 1:5, s. 792-797
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Tidskriftsartikel (refereegranskat)abstract
- In the pursuit of developing new materials for more efficient bulk-heterojunction solar cells, the blend poly (3-hexylthiophene):[ 6,6]-phenyl-C(61)-butyric acid methyl ester (P3HT:PCBM) serves as an important model system. The success of the P3HT: PCBM blend comes from efficient charge generation and transport with low recombination. There is not, however, a good microscopic picture of what causes these, hindering the development of new material systems. In this report UV photoelectron spectroscopy measurements on both regiorandom-(rra) and regioregular-(rr) P3HT are presented, and the results are interpreted using the Integer Charge Transfer model. The results suggest that spontaneous charge transfer from P3HT to PCBM occurs after heat treatment of P3HT: PCBM blends. The resulting formation of an interfacial dipole creates an extra barrier at the interface explaining the reduced (non-)geminate recombination with increased charge generation in heat treated rr-P3HT: PCBM blends. Extensive photoinduced absorption measurements using both above-and below-bandgap excitation light are presented, in good agreement with the suggested dipole formation.
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| 3. |
- Abbas, Muhammad, et al.
(författare)
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Computational and Implementation Complexity of Polynomial Evaluation Schemes
- 2011
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Ingår i: Proceedings of NORCHIP, 2011 Date:14-15 Nov. 2011. - : IEEE conference proceedings. - 9781457705151 - 9781457705144 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider the computational complexity of different polynomial evaluation schemes. By considering the number of operations of different types, critical path, pipelining complexity, and latency after pipelining, high-level comparisons are obtained. These can then be used to short list suitable candidates for an implementation given the specifications. Not only multiplications are considered, but they are divided into data-data multiplications, squarers, and data-coefficient multiplications, as the latter can be optimized depending on implementation architecture and application.
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| 4. |
- Abbas, Qaisar, 1975-
(författare)
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Weak Boundary and Interface Procedures for Wave and Flow Problems
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks.Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability.Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.
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| 5. |
- Abbey, Susan E., et al.
(författare)
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Qualitative interviews versus standardised self-report questionnaires in assessing qualityb of life in heart transplant recipients
- 2011
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Ingår i: The Journal of Heart and Lung Transplantation. - : Elsevier. - 1053-2498 .- 1557-3117. ; 30:8, s. 963-966
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Tidskriftsartikel (refereegranskat)abstract
- Quality of life (QoL) studies in heart transplant recipients (HTRs) using validated, quantitative, self-report questionnaires have reported poor QoL in approximately 20% of patients. This consecutive mixed methods study compared self-report questionnaires, the Medical Outcomes Study 36-item Short Form Health Survey (MOS SF-36) and the Atkinson Life Satisfaction Scale, with phenomenologically informed audiovisual (AV) qualitative interview data in 27 medically stable HTRs (70% male; age 53 ± 13.77 years; time since transplant 4.06 ± 2.42 years). Self-report questionnaire data reported poor QoL and more distress compared with previous studies and normative population samples; in contrast, 52% of HTRs displayed pervasive distress according to visual methodology. Using qualitative methods to assess QoL yields information that would otherwise remain unobserved by the exclusive use of quantitative QOL questionnaires.
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| 6. |
- Abbott, Allan, et al.
(författare)
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Leg pain and psychological variables predict outcome 2-3 years after lumber fusion surgery
- 2011
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Ingår i: European spine journal. - : Springer. - 0940-6719 .- 1432-0932. ; 20:10, s. 1626-1634
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Tidskriftsartikel (refereegranskat)abstract
- Prediction studies testing a thorough range of psychological variables in addition to demographic, work-related and clinical variables are lacking in lumbar fusion surgery research. This prospective cohort study aimed at examining predictions of functional disability, back pain and health-related quality of life (HRQOL) 2-3 years after lumbar fusion by regressing nonlinear relations in a multivariate predictive model of pre-surgical variables. Before and 2-3 years after lumbar fusion surgery, patients completed measures investigating demographics, work-related variables, clinical variables, functional self-efficacy, outcome expectancy, fear of movement/(re)injury, mental health and pain coping. Categorical regression with optimal scaling transformation, elastic net regularization and bootstrapping were used to investigate predictor variables and address predictive model validity. The most parsimonious and stable subset of pre-surgical predictor variables explained 41.6, 36.0 and 25.6% of the variance in functional disability, back pain intensity and HRQOL 2-3 years after lumbar fusion. Pre-surgical control over pain significantly predicted functional disability and HRQOL. Pre-surgical catastrophizing and leg pain intensity significantly predicted functional disability and back pain while the pre-surgical straight leg raise significantly predicted back pain. Post-operative psychomotor therapy also significantly predicted functional disability while pre-surgical outcome expectations significantly predicted HRQOL. For the median dichotomised classification of functional disability, back pain intensity and HRQOL levels 2-3 years post-surgery, the discriminative ability of the prediction models was of good quality. The results demonstrate the importance of pre-surgical psychological factors, leg pain intensity, straight leg raise and post-operative psychomotor therapy in the predictions of functional disability, back pain and HRQOL-related outcomes.
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| 7. |
- Abbott, Allan, et al.
(författare)
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Patient’s experience post-lumbar fusion regarding back problems, recovery and expectations in terms of the international classification of functioning, disability and health.
- 2011
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Ingår i: Disability and Rehabilitation. - : Taylor & Francis. - 0963-8288 .- 1464-5165. ; 33:15-16, s. 1399-1408
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:To describe within the context of the International Classification of Functioning, Disability and Health (ICF), patient's experiences post-lumber fusion regarding back problems, recovery and expectations of rehabilitation and to contrast with the content of outcome measures and the ICF low back pain (LBP) core sets.METHODS:The study has a cross-sectional and retrospective design and involves 20 lumbar fusion patients. Using the ICF, qualitative content analysis of semi-structured interviews 3-6 months post-surgery was performed. This was compared with the ICF related content of the Oswestry Disability Index (ODI), Medical Outcome Study Short Form 36 (SF-36), European Quality of Life Questionnaire (EQ5D) and the ICF LBP core sets.RESULTS:Patient's experiences were most frequently linked to psychological, sensory, neuromusculoskeletal and movement related body function chapters of the ICF. The most frequently linked categories of activity and participation were mobility, domestic activities, family relationships, work, recreation and leisure. Environmental factors frequently linked were the use of analgesics, walking aids, family support, social security systems, health care systems and labour market employment services.CONCLUSIONS:This study highlights important ICF related aspects of patient's experiences post-lumber fusion. The use of the comprehensive ICF core sets is recommended in conjunction with ODI, SF-36 and the EQ5D for a broader analysis of patient outcomes post-lumbar fusion.
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| 8. |
- Abbott, Allan, et al.
(författare)
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The effectiveness of physiotherapeutic rehabilitation and issues of outcome prediction after lumber fusion surgery.
- 2011
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Ingår i: Proceedings of the WCPT Congress, Amsterdam Netherlands.. - : World Confederation of Physical Therapy. ; , s. 20-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: The primary purpose was to analyse the short and long term effectiveness of physiotherapeutic rehabilitation programs performed during the first 3 month after lumbar fusion surgery. A secondary purpose was to analyse factors predicting long-term disability, back pain and health related quality of life (HRQOL) outcomes after lumbar fusion.Relevance: The study provides evidence for the effectiveness of early physiotherapy after lumbar fusion. Furthermore improved knowledge of predictive factors can help physiotherapist in the screening of lumbar fusion candidates and the individualised implementation of pre-surgical and post-surgical interventions.Participants: A total of 107 patients were recruited from the Karolinska University Hospital's Orthopaedic Clinic, Stockholm, Sweden. The inclusion criteria were: men and women aged between 18 and 65 years with a >12 month history of back pain and/or sciatica; a primary diagnosis of spinal stenosis, degenerative or isthmic spondylolisthesis or degenerative disc disease; selected for lumbar fusion with or without decompression; competence in the Swedish language. The criteria for exclusion were: previous lumbar fusion, rheumatoid arthritis and ankylosing spondylitis.Methods: An open book randomised controlled trial with pre-surgical and post-surgical measures at 3, 6, 12 and 24-36 months was performed to investigate the effectiveness of a psychomotor therapy focusing on cognition, behaviour and motor relearning compared to exercise therapy focusing on strength and conditioning, applied during the first 3 months after lumbar fusion. Randomisation allocated 53 patients to psychomotor therapy and 54 patients to exercise therapy. The Oswestry disability index (ODI) was the primary outcome measure. Secondary measures included the Visual analogue scale for back pain (VAS), European quality of life questionnaire (EQ5D), as well as other clinical, psychological and work related variables.Analysis: A total of 78 patients were needed assuming a power = 80%. Patient compliance was analysed and an intention to treat principle applied to data analysis. For statistical comparison between the 2 independent groups, analysis of covariance was used. Categorical regression with optimal scaling transformation, elastic net regularization and bootstrapping were used to investigate pre-surgical predictor variables and address predictive model validity.Results: Follow-up rates were 93% at 12 months and 81% at 24-36 months after surgery. Psychomotor therapy improved functional disability, self-efficacy, outcome expectancy and fear of movement/(re)injury significantly more than exercise therapy at respective follow-up occasions. Pre-surgical control over pain significantly predicted functional disability and HRQOL. Pre-surgical catastrophizing and leg pain intensity significantly predicted functional disability and back pain while the pre-surgical lasegue test significantly predicted back pain. The implementation of post-operative psychomotor therapy also significantly predicted functional disability while pre-surgical outcome expectations significantly predicted HRQOL.Conclusions: The study shows that post-operative rehabilitation can be safely implemented during the first 3 months after lumbar fusion and should include measures to modify psychological as well as motor functions. The study also demonstrates the importance of pre-surgical psychological factors, leg pain intensity, the lasegue test and post-operative psychomotor therapy in the predictions of functional disability, back pain and HRQOL related outcomes.Implications: Physiotherapist should screen patients pain, psychological factors and neuromusculoskeletal system pre-surgically and rehabilitate patients with early psychomotor therapy after lumbar fusion.
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| 9. |
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| 10. |
- Abelius, Martina S, et al.
(författare)
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High cord blood levels of the T-helper 2-associated chemokines CCL17 and CCL22 precede allergy development during the first 6 years of life
- 2011
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Ingår i: Pediatric Research. - 0031-3998 .- 1530-0447. ; 70:5, s. 495-500
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to a strong T-helper 2 (Th2)-like environment during fetal development may promote allergy development. Increased cord blood (CB) levels of the Th2-associated chemokine CCL22 were associated with allergy development during the first 2 y of life. The aim of the present study was to determine whether CB Th1- and Th2-associated chemokine levels are associated with allergy development during the first 6 y of life, allowing assessment of respiratory allergic symptoms usually developing in this period. The CB levels of cytokines, chemokines, and total IgE were determined in 56 children of 20 women with allergic symptoms and 36 women without allergic symptoms. Total IgE and allergen-specific IgE antibody levels were quantified at 6, 12, 24 mo, and 6 y of age. Increased CB CCL22 levels were associated with development of allergic sensitization and asthma and increased CCL17 levels with development of allergic symptoms, including asthma. Sensitized children with allergic symptoms showed higher CB CCL17 and CCL22 levels and higher ratios between these Th2-associated chemokines and the Th1-associated chemokine CXCL10 than nonsensitized children without allergic symptoms. A pronounced Th2 deviation at birth, reflected by increased CB CCL17 and CCL22 levels, and increased CCL22/CXCL10 and CCL17/CXCL10 ratios might promote allergy development later in life.
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