| 6681. |
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| 6682. |
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| 6683. |
- Wadbro, Eddie, 1981-, et al.
(författare)
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High contrast microwave tomography using topology optimization techniques
- 2010
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Ingår i: Journal of Computational and Applied Mathematics. - : Elsevier BV. - 0377-0427 .- 1879-1778. ; 234:6, s. 1773-1780
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Tidskriftsartikel (refereegranskat)abstract
- Microwave tomography for medical applications leads to a difficult reconstruction problem for the dielectric properties of biological tissue due to strongly diffracting waves in combination with large dielectric contrasts. We apply the material distribution technique used for topology optimization of elastic structures in order to solve the nonlinear least-squares problem underlying the reconstruction problem. Using simulated numerical data with an approximate signal-to-noise ratio of 40 dB and geometrical a priori information on the unknown objects, we obtain good estimates of the dielectric properties corresponding to biological objects.
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| 6684. |
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| 6685. |
- Wadbro, Eddie, et al.
(författare)
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Shape and topology optimization of an acoustic horn-lens combination
- 2010
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Ingår i: Journal of Computational and Applied Mathematics. - : Elsevier. - 0377-0427 .- 1879-1778. ; 234:6, s. 1781-1787
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Tidskriftsartikel (refereegranskat)abstract
- Using gradient-based optimization combined with numerical solutions of the Helmholtz equation, we design an acoustic device with high transmission efficiency and even directivity throughout a two-octave-wide frequency range. The device consists of a horn, whose flare is subject to boundary shape optimization, together with an area in front of the horn, where solid material arbitrarily can be distributed using topology optimization techniques, effectively creating an acoustic lens.
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| 6686. |
- Waehrens, Eva Ejlersen, 1963-
(författare)
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Measuring quality of occupational performance based on self-report and observation : development and validation of instruments to evaluate ADL task performance
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background People with rheumatic or neurologic conditions are commonly referred for occupational therapy because of decreased ability to perform ADL tasks. Upon referral, occupational therapists use a client-centred, occupationfocused approach when evaluating a person's perceived and observed quality of ADL task performance to clarify the nature and extent of the person’s problems, plan interventions and determine effectiveness of interventions. Evaluation of the extent of problems and change following intervention require the use of linear measures of ADL. The aim of this doctoral thesis was to develop and validate linear measures of perceived and observed quality of ADL task performance for occupational therapy clinical praxis and research. Methods To develop linear measures of observed quality of ADL task performance based on Rasch measurement methods, clients with ABI (n=70) were evaluated using a 3-category rating scale and the ADL Taxonomy. Similarly, to develop linear measures of perceived quality of ADL task performance women with rheumatic diseases (n=118) reported their ability on a questionnaire and in an interview based on the ADL Taxonomy and a 4- category rating scale. To further validate the ADL ability measures of the Assessment of Motor and Process Skills (AMPS) data were collected in two samples. In a sample of women with chronic widespread pain (CWP) or fibromyalgia (FM) (n=50) the ADL ability measures were validated with regard to discrimination, stability and sensitivity to changes. Discrimination was examined by comparing AMPS data from women with CWP/FM to those of healthy women. Stability and sensitivity to change were examined based on repeated AMPS observations pre and post intervention. In addition, sensitivity to change was examined in a sample of clients with ABI (n=36) using a pre- and post-test design. Finally, the validity of the AMPS ADL ability measures in relation to perceived ADL ability was examined in women with rheumatic diseases (n=118) and women with CWP/FM (n=50). Results Based on the results of the four studies in this thesis, we were able to conclude that it was possible to obtain linear measures of observed quality of ADL task performance based on a revised version of the ADL Taxonomy (ADL-O). It was also possible to obtain linear measures of perceived quality of ADL task performance based on revised versions of the ADL Taxonomy using the formats of questionnaires (ADL-Q) and interviews (ADL-I). Moreover, it was possible to establish further evidence of validity of the ADL ability measures of the AMPS. Thus, the AMPS ADL ability measures could discriminate between women with CWP/FM and healthy women. The ADL ability measures of remained stable when no intervention was provided and the ADL motor ability measures were sensitive to change among women with CWP/FM. Moreover, the ADL ability measures were sensitive to change among clients with low ADL ability following ABI. Finally, only low to moderate correlations were found between measures of perceived and observed ADL ability. Conclusions Rasch analyses of revised versions of the ADL Taxonomy suggest that the majority of the ADL tasks and rating scales focused on quality of ADL task performance can be used to obtain linear measures of quality of ADL task performance based on methods of questionnaire, interview or observation. Furthermore, the studies provided evidence of validity of the ADL ability measures of the AMPS in relation to discrimination, stability and sensitivity to change and relation to perceived ADL ability. The results may, therefore, enhance the use of ADL instruments that provide linear measures of perceived and observed quality of ADL task performance in occupational therapy clinical praxis and research.
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| 6687. |
- Waehrens, Eva Ejlersen, 1963-, et al.
(författare)
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Performance-based assessment of activities of daily living (ADL) ability among women with chronic widespread pain
- 2010
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Ingår i: Pain. - : Ovid Technologies (Wolters Kluwer Health). - 0304-3959 .- 1872-6623. ; 150:3, s. 535-541
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Tidskriftsartikel (refereegranskat)abstract
- Functional ability, including the ability to perform activities of daily living (ADL), is considered a core outcome domain in chronic pain clinical trials and is usually assessed through generic or disease-specific self-report questionnaires. Research, however, indicates that self-report and performance-based assessment of ADL offer distinct but complementary information about ability. The present study, therefore, investigated the applicability of a performance-based measure of ADL ability, the Assessment of Motor and Process Skills (AMPS), among 50 women with chronic widespread pain. The investigated psychometric properties of the AMPS included discrimination between a sample of healthy women and those with chronic widespread pain, as well as stability when no intervention was provided and sensitivity to change following intervention. Data were obtained based on a repeated measures design performing AMPS evaluations twice pre- and twice post-rehabilitation. Results indicated that the ADL motor ability measures of the participants were significantly lower than those of healthy women of same age, the ADL motor and ADL process ability measures remained stable when no intervention was provided and the ADL motor ability measures were sensitive to change following a 2-week interdisciplinary rehabilitation program. A weak correlation (rs = −0.35) was found between self-reported ADL ability as measured by the physical function subscale of the Functional Impact Questionnaire (FIQ) and performance-based ADL motor measures, and no correlation (rs = −0.02) was found between FIQ ADL measures and ADL process ability, supporting the need for both performance-based and self-reported assessment of ADL.
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| 6688. |
- Waenerlund, Anna-Karin, 1982-, et al.
(författare)
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Is temporary employment related to health status? : Analysis of the Northern Swedish Cohort.
- 2011
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Ingår i: Scandinavian Journal of Public Health. - : Sage Publications. - 1403-4948 .- 1651-1905. ; 39:5, s. 533-539
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The aim of this study was to investigate whether temporary employment was related to non-optimal self-rated healthand psychological distress at age 42 after adjustment for the same indicators at age 30, and to analyze the effects of jobinsecurity, low cash margin and high job strain on this relationship.Methods: A subcohort of the Northern Swedish Cohortthat was employed at the 2007 follow-up survey (n¼907, response rate of 94%) was analyzed using data from 1995 and 2007questionnaires.Results: Temporary employees had a higher risk of both non-optimal self-rated health and psychologicaldistress. After adjustment for non-optimal self-rated health at age 30 and psychological distress at age 30 as well as forsociodemographic variables, the odds ratios decreased but remained significant. However, after adjustment for job insecurity,high job strain and low cash margin the odds ratio dropped for non-optimal self-rated health but remained significant forpsychological distress.Conclusions: Temporary employment may have adverse effects on self-rated health andpsychological health after adjustment for previous health status and sociodemographic variables. Our findingsindicate that low cash margin and job insecurity may partially mediate the association between temporaryemployment and health status.
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| 6689. |
- Waenerlund, Anna-Karin, et al.
(författare)
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Is the core-periphery labour market structure related to perceived health? Findings of the Northern Swedish Cohort.
- 2011
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 11, s. 956-
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is controversy as to whether peripheral employment is related to poor health status or not. This study aims at examining whether 1) the accumulation of time in peripheral labour market positions is associated with psychological distress and poor or average self-rated health; 2) the proposed association is different among women than among men.Method: Participants in the 1995 and 2007 follow-up surveys of the Northern Swedish Cohort (n = 985) completed self-administered questionnaires about psychological and general health and about employment positions during the follow-up years. Associations between 12 year peripheral labour market positions (no, low, medium and high exposure) and health were examined using logistic regression.Results: Exposure to peripheral employment was positively related to psychological distress in both women and men (p-values for trend < 0.001). Adjustment for sociodemographics and psychological distress at baseline, as well as for unemployment and being out of the labour market at the follow-up, resulted in attenuation of the odds ratios, particularly in the group with high exposure to peripheral employment, although results remained significant in men in the fully adjusted model. Women and men with high exposure to peripheral employment had high odds of poor or average self-rated health, but the association was rendered non-significant after adjustment for the covariates.Conclusions: Our findings suggest that exposure to peripheral employment positions has an impact particularly on mental health, partly due to the over-representation of other unfavourable social and employment conditions among those with substantial exposure to peripheral employment.
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| 6690. |
- Waernbaum, Ingeborg, 1972-
(författare)
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Propensity score model specification for estimation of average treatment effects
- 2010
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Ingår i: Journal of Statistical Planning and Inference. - Amsterdam : Elsevier. - 0378-3758 .- 1873-1171. ; 140:7, s. 1948-1956
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Tidskriftsartikel (refereegranskat)abstract
- Treatment effect estimators that utilize the propensity score as a balancing score, e.g., matching and blocking estimators are robust to misspecifications of the propensity score model when the misspecification is a balancing score. Such misspecifications arise from using the balancing property of the propensity score in the specification procedure. Here, we study misspecifications of a parametric propensity score model written as a linear predictor in a strictly monotonic function, e.g. a generalized linear model representation. Under mild assumptions we show that for misspecifications, such as not adding enough higher order terms or choosing the wrong link function, the true propensity score is a function of the misspecified model. Hence, the latter does not bring bias to the treatment effect estimator. It is also shown that a misspecification of the propensity score does not necessarily lead to less efficient estimation of the treatment effect. The results of the paper are highlighted in simulations where different misspecifications are studied.
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