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- Kelly, J. J., et al.
(författare)
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Recoil polarization measurements for neutral pion electroproduction at Q(2)=1(GeV/c)(2) near the Delta resonance
- 2007
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:2
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Tidskriftsartikel (refereegranskat)abstract
- We measured angular distributions of differential cross section, beam analyzing power, and recoil polarization for neutral pion electroproduction at Q(2)=1.0 (GeV/c)(2) in 10 bins of 1.17 <= W <= 1.35 GeV across the Delta resonance. A total of 16 independent response functions were extracted, of which 12 were observed for the first time. Comparisons with recent model calculations show that response functions governed by real parts of interference products are determined relatively well near the physical mass, W=M-Delta approximate to 1.232 GeV, but the variation among models is large for response functions governed by imaginary parts, and for both types of response functions, the variation increases rapidly with W > M-Delta. We performed a multipole analysis that adjusts suitable subsets of center dot(pi)<= 2 amplitudes with higher partial waves constrained by baseline models. This analysis provides both real and imaginary parts. The fitted multipole amplitudes are nearly model independent-there is very little sensitivity to the choice of baseline model or truncation scheme. By contrast, truncation errors in the traditional Legendre analysis of N ->Delta quadrupole ratios are not negligible. Parabolic fits to the W dependence around M-Delta for the multiple analysis gives values for Re(S1+/M1+)=(-6.61 +/- 0.18)% and Re(E1+/M1+)=(-2.87 +/- 0.19)% for the p pi(0) channel at W=1.232 GeV and Q(2)=1.0 (GeV/c)(2) that are distinctly larger than those from the Legendre analysis of the same data. Similarly, the multipole analysis gives Re(S0+/M1+)=(+7.1 +/- 0.8)% at W=1.232 GeV, consistent with recent models, while the traditional Legendre analysis gives the opposite sign because its truncation errors are quite severe.
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| 2. |
- Ng, M Y M, et al.
(författare)
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Meta-analysis of 32 genome-wide linkage studies of schizophrenia
- 2009
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Ingår i: Molecular Psychiatry. - : Springer Science and Business Media LLC. - 1359-4184 .- 1476-5578. ; 14:8, s. 774-785
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Tidskriftsartikel (refereegranskat)abstract
- A genome scan meta-analysis (GSMA) was carried out on 32 independent genome-wide linkage scan analyses that included 3255 pedigrees with 7413 genotyped cases affected with schizophrenia (SCZ) or related disorders. The primary GSMA divided the autosomes into 120 bins, rank-ordered the bins within each study according to the most positive linkage result in each bin, summed these ranks (weighted for study size) for each bin across studies and determined the empirical probability of a given summed rank (P(SR)) by simulation. Suggestive evidence for linkage was observed in two single bins, on chromosomes 5q (142-168 Mb) and 2q (103-134 Mb). Genome-wide evidence for linkage was detected on chromosome 2q (119-152 Mb) when bin boundaries were shifted to the middle of the previous bins. The primary analysis met empirical criteria for 'aggregate' genome-wide significance, indicating that some or all of 10 bins are likely to contain loci linked to SCZ, including regions of chromosomes 1, 2q, 3q, 4q, 5q, 8p and 10q. In a secondary analysis of 22 studies of European-ancestry samples, suggestive evidence for linkage was observed on chromosome 8p (16-33 Mb). Although the newer genome-wide association methodology has greater power to detect weak associations to single common DNA sequence variants, linkage analysis can detect diverse genetic effects that segregate in families, including multiple rare variants within one locus or several weakly associated loci in the same region. Therefore, the regions supported by this meta-analysis deserve close attention in future studies.
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| 5. |
- Davis, A M, et al.
(författare)
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The development of a short measure of physical function for hip OA HOOS-Physical Function Shortform (HOOS-PS): an OARSI/OMERACT initiative
- 2008
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 16:5, s. 551-559
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To derive a cross-culturally valid, short measure of physical function using function subscales (daily living and sports and recreation) of the Hip disability and Osteoarthritis Outcome Score (HOOS). Methods: Rasch analysis was conducted on data from individuals from multiple countries who had hip osteoarthritis (OA). Fit of the data to the Rasch model was evaluated by model chi(2) and item fit statistics (chi(2), size of residual, and F-test). Differential item functioning was evaluated by gender, age and country. Unidimensionality was evaluated by factor analysis of residuals. Individual data sets were analyzed and data pooled and re-analyzed for fit to the model. Regression modeling was conducted to derive a nomogram converting raw summed scores to Rasch derived interval scores. Results: Seven data sets were included (n = 2991), ages 19-96 years, male/female ratio was 1:1.23. The final model included five HOOS items. From the easiest to most difficult, the items (logit) were as follows: sitting (1.832), descending stairs (0.729), getting in/out of bath or shower (0.255), twisting/pivoting on loaded leg (-0.221) and running (-2.595). The separation index was 0.80. Conclusion: The daily activity and sports and recreational items of the HOOS were reduced to five items achieving a feasible, short measure of physical function with interval level properties. This tool has potential for use as the function component of an OA severity scoring system. Further testing of this measure is warranted.
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| 6. |
- Perruccio, A V, et al.
(författare)
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The development of a short measure of physical function for knee OA KOOS-Physical Function Shortform (KOOS-PS) - an OARSI/OMERACT initiative
- 2008
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 16:5, s. 542-550
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To develop a short measure of physical function for knee osteoarthritis (OA) using multi-national data from. individuals with varying degrees of severity of knee OA. Methods: Rasch analysis, based on the partial credit model, was conducted on Knee injury and Osteoarthritis Outcome Score and Western Ontario McMaster Universities' Osteoarthritis Index data from individuals with knee OA, ranging from community to pre-total knee replacement samples from five countries. Fit of the data to the Rasch model was evaluated by overall model fit and item-level fit statistics (chi(2), size of residual, F-test). Invariance across age, gender and country was evaluated. Unidimensionality was evaluated by factor analysis of residuals. The derived short measure was further tested for fit through re-analyses in individual sub-samples. A nomogram converting raw summed scores to Rasch-derived interval scores was developed. Results: Thirteen data sets were included (n = 2145), with an age range of 26-95 years, and a male/female ratio of 1:1.4. The final model included seven of the original 22 items. From easiest to most difficult, the items (logit) were as follows: rising from bed (1.366), putting on socks/stockings (1.109), rising from sitting (0.537), bending to the floor (0.433), twisting/pivoting on injured knee (-0.861), kneeling (-1.292) and squatting (-1.292). Sub-sample analyses confirmed findings. Conclusion: Based on the use of accepted Rasch-based measurement methods and the compliment of countries, languages and OA severity represented in this study, our seven item short measure of physical function for knee OA is likely generalizable and widely applicable. This measure has potential for use as the function component in an OA severity scoring system.
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| 8. |
- Davis, A. M., et al.
(författare)
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Comparative, validity and responsiveness of the HOOS-PS and KOOS-PS to the WOMAC physical function subscale in total joint replacement for Osteoarthritis
- 2009
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Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 17:7, s. 843-847
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate the internal consistency of the Hip disability and Osteoarthritis Outcome Score-Physical Function Short-form (HOOS-PS) and the Knee injury and Ostecarthritis Outcome Score-Physical Function Short-form (KOOS-PS) in total hip replacement (THR) and total knee (TKR) replacement. Construct validity and responsiveness were compared to the Western Ontario McMaster Universities' Osteoarthritis Index (WOMAC) Likert 3.0 physical function (PF) subscale and the PF excluding the items in the short measures (PF-exclusions). Methods: Participants completed the full HOOS or KOOS, measures of fatigue, anxiety. depression and the Chronic Pain Grade (CPG) pre-surgery and the HOOS or KOOS 6 months post-surgery. Internal consistency for the HOOS-PS and KOOS-PS was calculated using Cronbach's alpha. For construct validity, it was hypothesized that correlations between the HOOS-PS or KOOS-PS and PF and PF-exclusions with fatigue, CPG, anxiety and depression and HOOS/KOOS pain scales would differ by magnitudes of <0.1. Standardized response means (SRMs) were calculated for the HOOS-PS, KOOS-PS, PF and PF-exclusions and hypothesized to be >1. Results: The THR group (n = 201) had a mean age of 62.3 years; 53.2% were female. The TKR group (n = 248) had a mean age of 64.5 years; 63.7% were female. Cronbach's alpha was 0.79 and 0.89 for the HOOS-PS and KOOS-PS, respectively, confirming that the measures represented a homogeneous construct. The correlation of the HOOS-PS to the PF and PF-exclusions was 0.90 and 0.86, respectively; r = 0.90 (PF) and r = 0.85 (PF-exclusions) for the KOOS-PS. The results supported the construct validity hypotheses. For THR, the SRM was 1.5, 1.7 and 1.7 for the HOOS-PS, PF and PF-exclusions; for TKR, the SRM was 1.4, 1.5 and 1.7, respectively. Conclusions: The short HOOS-PS and KOOS-PS represent homogenous short measures of PF with similar construct validity and responsiveness to the 17-item PF. The HOOS-PS and KOOS-PS are parsimonious, valid and responsive for evaluating PF in THR and TKR. (C) 2009 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
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| 9. |
- Aziz, N. A., et al.
(författare)
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Weight loss in Huntington disease increases with higher CAG repeat number
- 2008
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 1526-632X .- 0028-3878. ; 71:19, s. 1506-1513
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Huntington disease (HD) is a hereditary neurodegenerative disorder caused by an expanded number of CAG repeats in the huntingtin gene. A hallmark of HD is unintended weight loss, the cause of which is unknown. In order to elucidate the underlying mechanisms of weight loss in HD, we studied its relation to other disease characteristics including motor, cognitive, and behavioral disturbances and CAG repeat number. Methods: In 517 patients with early stage HD, we applied mixed-effects model analyses to correlate weight changes over 3 years to CAG repeat number and various components of the Unified Huntington's Disease Rating Scale (UHDRS). We also assessed the relation between CAG repeat number and body weight and caloric intake in the R6/2 mouse model of HD. Results: In patients with HD, mean body mass index decreased with -0.15 units per year (p < 0.001). However, no single UHDRS component, including motor, cognitive, and behavioral scores, was independently associated with the rate of weight loss. Patients with HD with a higher CAG repeat number had a faster rate of weight loss. Similarly, R6/2 mice with a larger CAG repeat length had a lower body weight, whereas caloric intake increased with larger CAG repeat length. Conclusions: Weight loss in Huntington disease (HD) is directly linked to CAG repeat length and is likely to result from a hypermetabolic state. Other signs and symptoms of HD are unlikely to contribute to weight loss in early disease stages. Elucidation of the responsible mechanisms could lead to effective energy-based therapeutics. Neurology (R) 2008;71:1506-1513
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