| 1. |
- Abdellah, Tebani, et al.
(författare)
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Integration of molecular profiles in a longitudinal wellness profiling cohort.
- 2020
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- An important aspect of precision medicine is to probe the stability in molecular profiles among healthy individuals over time. Here, we sample a longitudinal wellness cohort with 100 healthy individuals and analyze blood molecular profiles including proteomics, transcriptomics, lipidomics, metabolomics, autoantibodies andimmune cell profiling, complementedwith gut microbiota composition and routine clinical chemistry. Overall, our results show high variation between individuals across different molecular readouts, while the intra-individual baseline variation is low. The analyses show that each individual has a unique and stable plasma protein profile throughout the study period and that many individuals also show distinct profiles with regards to the other omics datasets, with strong underlying connections between the blood proteome and the clinical chemistry parameters. In conclusion, the results support an individual-based definition of health and show that comprehensive omics profiling in a longitudinal manner is a path forward for precision medicine.
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| 2. |
- Bridel, Claire, et al.
(författare)
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Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology : A Systematic Review and Meta-analysis
- 2019
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Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149 .- 2168-6157. ; 76:9, s. 1035-1048
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Forskningsöversikt (refereegranskat)abstract
- Importance Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.Objectives To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.Data Sources PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.Study Selection Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.Data Extraction and Synthesis Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.Main Outcome and Measure The cNfL levels adjusted for age and sex across diagnoses.Results Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.Conclusions and Relevance These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.
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| 3. |
- Hu, Min, 1979-, et al.
(författare)
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Grading of sawn timber using the vibration technique : locating imperfections based on flexural mode shapes
- 2011
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Ingår i: 17th international nondestructive testing and evaluation of wood symposium. - Sopron, Hungary : University of West Hungary. - 9789639883819 ; , s. 269-276
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Konferensbidrag (refereegranskat)abstract
- The present study aims at investigating the potential of using mode shape or mode shape curvature (MSC) for detecting defects in wooden beams. It includes modal analysis, Finite Element (FE) modeling and visual scanning. An FE model was created to investigate the effect of defects of different size and location on the mode shape/MSC. The mode shape/MSC showed a good potential to be used for finding defects. An experimental study on 17 boards of Norway spruce, dimensions of 50×150×3900 mm, was conducted using experimental modal analysis. The findings reveal that: (1) the mode shape/MSC studied in the FE-model could be used to locate defects, (2) the method is very sensitive to measurement noise and it requires an accurately measured mode shape, (3) an error analysis shows that it is not possible to achieve the accuracy needed using accelerometers.
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| 4. |
- Wallin, Anders, 1950, et al.
(författare)
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Alzheimer's disease-subcortical vascular disease spectrum in a hospital-based setting: overview of results from the Gothenburg MCI and dementia studies.
- 2016
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 36:1, s. 95-113
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Forskningsöversikt (refereegranskat)abstract
- The ability to discriminate between Alzheimer's disease (AD), subcortical vascular disease, and other cognitive disorders is crucial for diagnostic purposes and clinical trial outcomes. Patients with primarily subcortical vascular disease are unlikely to benefit from treatments targeting the AD pathogenic mechanisms and vice versa. The Gothenburg mild cognitive impairment (MCI) and dementia studies are prospective, observational, single-center cohort studies suitable for both cross-sectional and longitudinal analysis that outline the cognitive profiles and biomarker characteristics of patients with AD, subcortical vascular disease, and other cognitive disorders. The studies, the first of which started in 1987, comprise inpatients with manifest dementia and patients seeking care for cognitive disorders at an outpatient memory clinic. This article gives an overview of the major published papers (neuropsychological, imaging/physiology, and neurochemical) of the studies including the ongoing Gothenburg MCI study. The main findings suggest that subcortical vascular disease with or without dementia exhibit a characteristic neuropsychological pattern of mental slowness and executive dysfunction and neurochemical deviations typical of white matter changes and disturbed blood-brain barrier function. Our findings may contribute to better healthcare for this underrecognized group of patients. The Gothenburg MCI study has also published papers on multimodal prediction of dementia, and cognitive reserve.Journal of Cerebral Blood Flow & Metabolism advance online publication, 29 July 2015; doi:10.1038/jcbfm.2015.148.
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| 5. |
- Wallin, Anders, 1950, et al.
(författare)
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The Gothenburg MCI study: design and distribution of Alzheimer's disease and subcortical vascular disease diagnoses from baseline to 6-year follow-up.
- 2016
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 36:1, s. 114-131
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Tidskriftsartikel (refereegranskat)abstract
- There is a need for increased nosological knowledge to enable rational trials in Alzheimer's disease (AD) and related disorders. The ongoing Gothenburg mild cognitive impairment (MCI) study is an attempt to conduct longitudinal in-depth phenotyping of patients with different forms and degrees of cognitive impairment using neuropsychological, neuroimaging, and neurochemical tools. Particular attention is paid to the interplay between AD and subcortical vascular disease, the latter representing a disease entity that may cause or contribute to cognitive impairment with an effect size that may be comparable to AD. Of 664 patients enrolled between 1999 and 2013, 195 were diagnosed with subjective cognitive impairment (SCI), 274 with mild cognitive impairment (MCI), and 195 with dementia, at baseline. Of the 195 (29%) patients with dementia at baseline, 81 (42%) had AD, 27 (14%) SVD, 41 (21%) mixed type dementia (=AD+SVD=MixD), and 46 (23%) other etiologies. After 6 years, 292 SCI/MCI patients were eligible for follow-up. Of these 292, 69 (24%) had converted to dementia (29 (42%) AD, 16 (23%) SVD, 15 (22%) MixD, 9 (13%) other etiologies). The study has shown that it is possible to identify not only AD but also incipient and manifest MixD/SVD in a memory clinic setting. These conditions should be taken into account in clinical trials.Journal of Cerebral Blood Flow & Metabolism advance online publication, 15 July 2015; doi:10.1038/jcbfm.2015.147.
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| 6. |
- Abbadi, Ahmad, et al.
(författare)
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Validation of the Health Assessment Tool (HAT) based on four aging cohorts from the Swedish National study on Aging and Care
- 2024
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Ingår i: BMC Medicine. - : BioMed Central (BMC). - 1741-7015. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: As global aging accelerates, routinely assessing the functional status and morbidity burden of older patients becomes paramount. The aim of this study is to assess the validity of the comprehensive clinical and functional Health Assessment Tool (HAT) based on four cohorts of older adults (60 + years) from the Swedish National study on Aging and Care (SNAC) spanning urban, suburban, and rural areas.Methods: The HAT integrates five health indicators (gait speed, global cognition, number of chronic diseases, and basic and instrumental activities of daily living), providing an individual-level score between 0 and 10. The tool was constructed using nominal response models, first separately for each cohort and then in a harmonized dataset. Outcomes included all-cause mortality over a maximum follow-up of 16 years and unplanned hospital admissions over a maximum of 3 years of follow-up. The predictive capacity was assessed through the area under the curve (AUC) using logistic regressions. For time to death, Cox regressions were performed, and Harrell’s C-indices were reported. Results from the four cohorts were pooled using individual participant data meta-analysis and compared with those from the harmonized dataset.Results: The HAT demonstrated high predictive capacity across all cohorts as well as in the harmonized dataset. In the harmonized dataset, the AUC was 0.84 (95% CI 0.81–0.87) for 1-year mortality, 0.81 (95% CI 0.80–0.83) for 3-year mortality, 0.80 (95% CI 0.79–0.82) for 5-year mortality, 0.69 (95% CI 0.67–0.70) for 1-year unplanned admissions, and 0.69 (95% CI 0.68–0.70) for 3-year unplanned admissions. The Harrell’s C for time-to-death throughout 16 years of follow-up was 0.75 (95% CI 0.74–0.75).Conclusions: The HAT is a highly predictive, clinically intuitive, and externally valid instrument with potential for better addressing older adults’ health needs and optimizing risk stratification at the population level. © The Author(s) 2024.
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| 7. |
- Balachandramurthi, Arun Ramanathan, 1989-, et al.
(författare)
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Microstructure tailoring in Electron Beam Powder Bed Fusion Additive Manufacturing and its potential consequences
- 2019
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Ingår i: Results in Materials. - : Elsevier. - 2590-048X. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Electron Beam Powder Bed Fusion process for Alloy 718 was investigated, in the sense of microstructural evolution with varying process conditions. The existence of a geometric relationship between the melt front and the processing parameters was observed. By understanding and capitalizing on this relationship, it was possible to obtain columnar, equiaxed or bimodal microstructure.
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| 8. |
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| 9. |
- Hu, Min, 1979-, et al.
(författare)
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Assessment of a Three-Dimensional Fiber Orientation Model for Timber
- 2016
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Ingår i: Wood and Fiber Science. - 0735-6161. ; 48:4, s. 271-290
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Tidskriftsartikel (refereegranskat)abstract
- Wood is an orthotropic material with very different properties along and across fibers, and every board has its own pattern of knots and fiber deviations. Therefore, detailed knowledge of the three-dimensional (3D) fiber orientation of individual boards would enable more accurate assessment of properties such as stiffness, strength, and shape stability. This paper presents a method for modeling 3D fiber orientation of side boards of Norway spruce. The method is based on dot laser scanning and utilization of the tracheid effect, and it is verified by a comparison between strain fields calculated on the basis of the fiber orientation model and corresponding strains determined using digital image correlation (DIC) technique. By means of the method, it is possible to identify knots and to reproduce the fiber orientation in clear wood in the vicinity of knots. Fiber orientation models of side boards including traversing edge knots were established and integrated in finite element models of boards used for simulation of four-point bending tests. The same boards were also tested in laboratory and displacement fields of the wide faces were recorded at different load levels using DIC technique. Comparisons of strain fields from measurements and simulations showed close agreement, regarding both strain patterns and strain levels. Local strain concentrations caused by very small defects were detected using the models and also found from the laboratory test results. The modeling approach may be used both to achieve improved accuracy of existing machine strength grading methods and, after further development, also for more advanced analysis of eg crack propagation and strength of timber.
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| 10. |
- Hu, Min, 1979-, et al.
(författare)
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Growth layer and fibre orientation around knots in Norway spruce : a laboratory investigation
- 2018
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Ingår i: Wood Science and Technology. - : Springer. - 0043-7719 .- 1432-5225. ; 52:1, s. 7-27
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Tidskriftsartikel (refereegranskat)abstract
- The strength of structural timber largely depends on the occurrence of knots and on the local material directions in the surroundings of such knots. There is, however, a lack of methods for establishing a full dataset of the local material directions. The present research aims at the development and application of a laboratory method to assess the geometry of growth layers and the orientation of fibres in a high-resolution 3D grid within wood specimens containing knots. The laboratory method was based on optical flatbed scanning and laser scanning, the former resulting in surface images and the latter, utilizing the tracheid effect, resulting in in-plane fibre angles determined in high-resolution grids on scanned surfaces. A rectangular solid wood specimen containing a single knot was cut from a tree in such a way that it could be assumed that a plane of symmetry existed in the specimen. By splitting the specimen through this plane through the centre line of the knot, two new specimens with assumed identical but mirrored properties were achieved. On one of the new specimens, the longitudinal-radial plane was subsequently scanned, and the longitudinal–tangential plane was scanned on the other. Then, by repeatedly planing off material on both specimens followed by scanning of the new surfaces that gradually appeared, 3D coordinate positions along different growth layers and 3D orientation of fibres in a 3D grid were obtained. Comparisons between detected fibre orientation and growth layer geometry were used for the assessment of the accuracy obtained regarding 3D fibre orientation. It was shown that the suggested method is well suited to capture growth layer surfaces and that it provides reliable information on 3D fibre orientation close to knots. Such knowledge is of great importance for understanding the properties of timber including knots. The quantitative data obtained are also useful for calibration of model parameters of general models on fibre orientation close to knots.
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| 11. |
- Hu, Min, 1979-, et al.
(författare)
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Modelling local bending stiffness based on fibre orientation in sawn timber
- 2018
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Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 76:6, s. 1605-1621
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Tidskriftsartikel (refereegranskat)abstract
- Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, has been utilized in a previously developed machine strength grading method, but rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections were adopted. The purpose of the present study was to suggest and verify a model with which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in the laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness profiles along boards. Comparisons of results indicated that the model suggested here was sufficient to capture the variation of local bending stiffness along boards with very high accuracy.
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| 12. |
- Hu, Min, 1979-, et al.
(författare)
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Modelling local bending stiffness of Norway spruce sawn timber using scanned fibre orientation
- 2018
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Ingår i: <em>Proceedings</em>, 2018, ICEM 2018. - : MDPI.
-
Konferensbidrag (refereegranskat)abstract
- Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, have been utilized in a previously developed machine strength grading method. However, that method was based on rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections. The purpose of the present study was to suggest and verify a model by which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness variation along boards. Comparisons of results indicated that models suggested herein were sufficient to capture the variation of local bending stiffness along boards with very high accuracy.
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| 13. |
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| 14. |
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| 15. |
- Jarnerö, Kirsi, et al.
(författare)
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In situ testing of timber floor vibration properties
- 2010
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Ingår i: <em>Proceedings of the 11th World Conference on Timber Engineering</em>.
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Konferensbidrag (refereegranskat)abstract
- In the present work the change in natural frequencies, damping and mode shapes of a prefabricated timber floor element have been investigated when it was integrated into a building structure. The timber floor element was first subjected to modal testing in laboratory with ungrounded and simply supported boundary conditions, and then in situ at different stages of building construction. The first five natural frequencies, damping ratios and mode shapes of the floor element and the entire floor were extracted and analysed. It may be concluded that the major change in natural frequencies occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that largely are constrained in their movement. Thein situ conditions have a great influence on the damping, which probably depends on the damping characteristics of the supports, but also on the fact that the floor is integrated into the building and interacts with it. There is a slight increase of damping in the floor over the different construction stages and the damping values seem to decrease with ascending mode order. The relative change also seems to decrease with increasing number of storeys built.
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| 16. |
- Jarnerö, Kirsi, et al.
(författare)
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Vibration properties of a timber floor assessed in laboratory and during building construction
- 2010
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Ingår i: <em>Proceedings of INTER-NOISE</em>.
-
Konferensbidrag (refereegranskat)abstract
- In the present work the change in natural frequencies, damping and mode shapes of a prefabricated timber floor element have been investigated when it was integrated into a building structure. The timber floor element was first subjected to modal testing in laboratory with ungrounded and simply supported boundary conditions, and then in situ at different stages of building construction. The first five natural frequencies, damping ratios and mode shapes of the floor element and the entire floor were extracted and analysed. It may be concluded that the major change in natural frequencies occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that largely are constrained in their movement. The in situ conditions have a great influence on the damping, which depends on the damping characteristics of the supports, but also on the fact that the floor is integrated into the building and interacts with it. There is a slight increase of damping in the floor over the different construction stages and the damping values seem to decrease with ascending mode order.
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| 17. |
- Jarnerö, Kirsi, et al.
(författare)
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Vibration properties of a timber floor assessed in laboratory and during construction
- 2015
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Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 82, s. 44-54
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Tidskriftsartikel (refereegranskat)abstract
- Natural frequencies, damping ratios and mode shapes of a prefabricated timber floor element have been assessed experimentally in laboratory with different boundary conditions and in situ (in field) at different stages of construction. In laboratory the change in modal parameters was studied with free-free boundary conditions and simply supported on two sides. Three different simply supported tests with changes in boundary conditions were carried out; the floor placed on the support without any fastening or interlayer between support and floor, the floor screwed to the supports and the floor placed on an elastic interlayer between support and floor. The in situ tests were carried out first on the single floor element and then on the entire floor of the room into which the floor element was built in. The damping ratio of the floor increased from 1% to 3% when simply supported in laboratory to approximately 5% when placed upon a polyurethane interlayer (Sylodyn®) in situ, and to approximately 6% when fully integrated in the building. Thus the in situconditions have considerable influence on the damping and the values assessed are very high in comparison with damping values suggested in design codes. Regarding natural frequencies it was concluded that the major change in these occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that are largely constrained in their movement.
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| 18. |
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| 19. |
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| 20. |
- Novakova, Lenka, 1984, et al.
(författare)
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Monitoring disease activity in multiple sclerosis using serum neurofilament light protein.
- 2017
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Ingår i: Neurology. - : Lippincott Williams & Wilkins. - 1526-632X .- 0028-3878. ; 89:22, s. 2230-2237
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Tidskriftsartikel (refereegranskat)abstract
- To examine the effects of disease activity, disability, and disease-modifying therapies (DMTs) on serum neurofilament light (NFL) and the correlation between NFL concentrations in serum and CSF in multiple sclerosis (MS).NFL concentrations were measured in paired serum and CSF samples (n = 521) from 373 participants: 286 had MS, 45 had other neurologic conditions, and 42 were healthy controls (HCs). In 138 patients with MS, the serum and CSF samples were obtained before and after DMT treatment with a median interval of 12 months. The CSF NFL concentration was measured with the UmanDiagnostics NF-light enzyme-linked immunosorbent assay. The serum NFL concentration was measured with an in-house ultrasensitive single-molecule array assay.In MS, the correlation between serum and CSF NFL was r = 0.62 (p < 0.001). Serum concentrations were significantly higher in patients with relapsing-remitting MS (16.9 ng/L) and in patients with progressive MS (23 ng/L) than in HCs (10.5 ng/L, p < 0.001 and p < 0.001, respectively). Treatment with DMT reduced median serum NFL levels from 18.6 (interquartile range [IQR] 12.6-32.7) ng/L to 15.7 (IQR 9.6-22.7) ng/L (p < 0.001). Patients with relapse or with radiologic activity had significantly higher serum NFL levels than those in remission (p < 0.001) or those without new lesions on MRI (p < 0.001).Serum and CSF NFL levels were highly correlated, indicating that blood sampling can replace CSF taps for this particular marker. Disease activity and DMT had similar effects on serum and CSF NFL concentrations. Repeated NFL determinations in peripheral blood for detecting axonal damage may represent new possibilities in MS monitoring.
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| 21. |
- Olofsson, Louise, 1977, et al.
(författare)
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Preliminary report: Zn-alpha2-glycoprotein genotype and serum levels are associated with serum lipids.
- 2010
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Ingår i: Metabolism. - : Elsevier BV. - 1532-8600 .- 0026-0495. ; 59:9, s. 1316-1318
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Tidskriftsartikel (refereegranskat)abstract
- Zn-alpha2-glycoprotein (ZAG) is a serum protein implicated in cancer cachexia and lipolysis. Our aim was to investigate serum levels of ZAG and polymorphisms in the ZAG gene in relation to serum lipids in man. Serum levels of ZAG correlated with serum levels of cholesterol (P = .00088) in healthy subjects and during weight loss (P = .059). The ZAG genotype was associated with total cholesterol (P = .014) and low-density lipoprotein cholesterol (P = .026) in healthy subjects, and the associations were replicated in an additional cohort (P = .0017 and P = .060, respectively). Our data indicate that ZAG plays a role in lipid metabolism.
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| 22. |
- Olsson, Anders, 1973-, et al.
(författare)
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Prediction of timber bending strength and in-member cross-sectional stiffness vartiation on basis of local wood fibre orientation
- 2013
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Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 71:3, s. 319-333
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Tidskriftsartikel (refereegranskat)abstract
- Machine strength grading of structural timber is based upon relationships between so called indicating properties (IPs) and bending strength. However, such relationships applied on the market today are rather poor. In this paper, new IPs and a new grading method resulting in more precise strength predictions are presented. The local fibre orientation on face and edge surfaces of wooden boards was identified using high resolution laser scanning. In combination with knowledge regarding basic wood material properties for each investigated board, the grain angle information enabled a calculation of the variation of the local MOE in the longitudinal direction of the boards. By integration over cross-sections along the board, an edgewise bending stiffness profile and a longitudinal stiffness profile, respectively, were calculated. A new IP was defined as the lowest bending stiffness determined along the board. For a sample of 105 boards of Norway spruce of dimension 45 × 145 × 3600 mm, a coefficient of determination as high as 0.68-0.71 was achieved between this new IP and bending strength. For the same sample, the coefficient of determination between global MOE, based on the first longitudinal resonance frequency and the board density, and strength was only 0.59. Furthermore, it is shown that improved accuracy when determining the stiffness profiles of boards will lead to even better predictions of bending strength. The results thus motivate both an industrial implementation of the suggested method and further research aiming at more accurately determined board stiffness profiles.
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| 23. |
- Olsson, Lisa M., 1984, et al.
(författare)
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Dynamics of the normal gut microbiota: A longitudinal one-year population study in Sweden
- 2022
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Ingår i: Cell Host and Microbe. - : Elsevier BV. - 1931-3128 .- 1934-6069. ; 30:5
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Tidskriftsartikel (refereegranskat)abstract
- Temporal dynamics of the gut microbiota potentially limit the identification of microbial features associated with health status. Here, we used whole-genome metagenomic and 16S rRNA gene sequencing to characterize the intra- and inter-individual variations of gut microbiota composition and functional potential of a disease-free Swedish population (n = 75) over one year. We found that 23% of the total compositional variance was explained by intra-individual variation. The degree of intra-individual compositional variability was negatively associated with the abundance of Faecalibacterium prausnitzii (a butyrate producer) and two Bifidobacterium species. By contrast, the abundance of facultative anaerobes and aerotolerant bacteria such as Escherichia coli and Lactobacillus acidophilus varied extensively, independent of compositional stability. The contribution of intra-individual variance to the total variance was greater for functional pathways than for microbial species. Thus, reliable quantification of microbial features requires repeated samples to address the issue of intra-individual variations of the gut microbiota.
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| 24. |
- Oscarsson, Jan, 1958-, et al.
(författare)
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Determination of tensile strain fields in Norway spruce side boards using two master-slave connected contact-free measurement systems based on digital image correlation.
- 2011
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Ingår i: Proceedings (Poster session) of the 17th International Nondestructive Testing and Evaluation of Wood Symposium, Sopron, Hungary, September 14-16, 2011..
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Konferensbidrag (refereegranskat)abstract
- A sample of nine Norway spruce side boards of narrow dimensions were tested in tension according to the standard EN 408. Strain fields were simultaneously measured using two master-slave connected measurement systems based on digital image correlation (DIC). Each system performed a separate measurement project measuring about 50% of the measurable length of each board and the results were combined, visualized and evaluated as one project using specific DIC software. The objectives were to investigate the possibility of measuring strain fields by use of multi-system measurements, to analyze the strain field distribution and to investigate the possibility of determining local modulus of elasticity (MOE) using strain field measurements. The results show that longitudinal strain fields were useful for identification of areas with reduced stiffness, that lateral board displacements, measured by the DIC systems, can be applied for identification of local defects, and that strain fields can be used for local MOE determination.
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| 25. |
- Oscarsson, Jan, 1958-, et al.
(författare)
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Determining tensile strain fields in Norway spruce side boards using two master-slave connected digital image correlation systems
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Machine strength grading of structural timber is in general based upon statistical relationships between bending strength and other timber properties (so called indicating properties). The overall aim of the research presented in this report was to investigate the possibility of obtaining a better understanding of such relationships using a contact-free deformation measurement technique based on digital image correlation (DIC). A sample of nine Norway spruce (Picea abies) side boards of narrow dimensions was tested in tension according to the European Standard EN 408. Deformations and strain fields along flatwise board surfaces were simultaneously determined using two master-slave connected DIC measurement systems. Each system performed a separate measurement project measuring slightly more than 50 % of the measurable length of each board and the results were combined, visualized and evaluated as one project using specific DIC software. The objectives were to investigate the possibility of identifying strain fields on timber pieces of narrow dimensions by use of multi-system measurements, to analyze the strain field distribution, and to investigate the possibility of determining local modulus of elasticity (MOE) using deformations and strain fields occurring on board surfaces. The results show that longitudinal strain fields can be useful for identification of areas with reduced stiffness and that lateral board displacements, measured by the DIC systems, can be applied for identification of local defects. Promising results were also achieved as regards local MOE determination on the basis of strain field measurements.
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| 26. |
- Oscarsson, Jan, 1958-, et al.
(författare)
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Strength grading of wet Norway spruce side boards by use of axial dynamic excitation
- 2010
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Ingår i: Proceedings of the 11th World Conference on Timber Engineering 2010, WCTE 2010, Riva del Garda, Trento, Italy, June 20-24. - : Curran Associates, Inc.. - 9781622761753 ; , s. 1601-1606
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Konferensbidrag (refereegranskat)abstract
- Strength grading of Norway spruce side boards in the wet state was investigated. For a batch of 58 boards, densities and dynamic modulus of elasticity in the axial direction, MOEdyn, were determined in the wet state. The boards were then split into two parts and the procedure of determining MOEdyn was repeated both before and after the boards were dried to a target moisture content of 12 %. Tensile strength of the split boards was measured and its relation to MOEdyn for both split and unsplit boards determined. A so called reversed lamination effect on the stiffness caused by the splitting of boards into two parts was also evaluated. The results show that strength grading of split boards in the wet state could give just as good results as grading performed after drying. The reversed lamination effect on the stiffness of split boards was found to be of lower order.
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| 27. |
- Roswall, Josefine, et al.
(författare)
-
Developmental trajectory of the healthy human gut microbiota during the first 5 years of life
- 2021
-
Ingår i: Cell Host & Microbe. - : Elsevier BV. - 1931-3128 .- 1934-6069. ; 29:5
-
Tidskriftsartikel (refereegranskat)abstract
- The gut is inhabited by a densely populated ecosystem, the gut microbiota, that is established at birth. However, the succession by which different bacteria are incorporated into the gut microbiota is still relatively unknown. Here, we analyze the microbiota from 471 Swedish children followed from birth to 5 years of age, collecting samples after 4 and 12 months and at 3 and 5 years of age as well as from their mothers at birth using 16S rRNA gene profiling. We also compare their microbiota to an adult Swedish population. Genera follow 4 different colonization patterns during establishment where Methanobrevibacter and Christensenellaceae colonize late and do not reached adult levels at 5 years. These late colonizers correlate with increased alpha diversity in both children and adults. By following the children through age-specific community types, we observe that children have individual dynamics in the gut microbiota development trajectory.
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| 28. |
- Saiki, Atsuhito, et al.
(författare)
-
Tenomodulin is highly expressed in adipose tissue, increased in obesity, and down-regulated during diet-induced weight loss.
- 2009
-
Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 94:10, s. 3987-94
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Tenomodulin (TNMD), a putative angiogenesis inhibitor, is expressed in hypovascular connective tissues. Global gene expression scans show that the TNMD gene also is expressed in human adipose tissue and that its expression is regulated in response to weight reduction; however, more detailed information is lacking. OBJECTIVE: The aim of this study was to investigate TNMD tissue distribution and TNMD gene expression in human adipose tissue in relation to obesity and metabolic disease. DESIGN, PATIENTS, AND INTERVENTIONS: TNMD gene expression, tissue distribution, and TNMD gene expression in adipose tissue from different depots, from lean and obese subjects, and during diet-induced weight reduction were analyzed by DNA microarray and real-time PCR. MAIN OUTCOME MEASURE: We primarily measured TNMD gene expression. RESULTS: The TNMD gene was predominantly expressed in sc adipose tissue. TNMD gene expression was higher in sc than omental adipose tissue both in lean (P = 0.002) and obese subjects (P = 0.014). In both women and men, TNMD gene expression was significantly higher in the obese subjects compared to the lean subjects (P = 1.1 x 10(-26) and P = 0.010, respectively). In a multiple linear regression analysis, BMI was a significant independent predictor of TNMD gene expression. TNMD gene expression was down-regulated during diet-induced weight loss, with a 65% decrease after 18 wk of diet (P < 0.0001). CONCLUSIONS: We conclude that human adipose tissue TNMD gene expression is highly affected by obesity, adipose tissue location, and weight loss, indicating that TNMD may play a role in adipose tissue function.
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| 29. |
- Sundström, Johan, Professor, 1971-, et al.
(författare)
-
Risk factors for subarachnoid haemorrhage : a nationwide cohort of 950 000 adults
- 2019
-
Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:6, s. 2018-2025
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Subarachnoid haemorrhage (SAH) is a devastating disease, with high mortality rate and substantial disability among survivors. Its causes are poorly understood. We aimed to investigate risk factors for SAH using a novel nationwide cohort consortium.METHODS: We obtained individual participant data of 949 683 persons (330 334 women) between 25 and 90 years old, with no history of SAH at baseline, from 21 population-based cohorts. Outcomes were obtained from the Swedish Patient and Causes of Death Registries.RESULTS: During 13 704 959 person-years of follow-up, 2659 cases of first-ever fatal or non-fatal SAH occurred, with an age-standardized incidence rate of 9.0 [95% confidence interval (CI) (7.4-10.6)/100 000 person-years] in men and 13.8 [(11.4-16.2)/100 000 person-years] in women. The incidence rate increased exponentially with higher age. In multivariable-adjusted Poisson models, marked sex interactions for current smoking and body mass index (BMI) were observed. Current smoking conferred a rate ratio (RR) of 2.24 (95% CI 1.95-2.57) in women and 1.62 (1.47-1.79) in men. One standard deviation higher BMI was associated with an RR of 0.86 (0.81-0.92) in women and 1.02 (0.96-1.08) in men. Higher blood pressure and lower education level were also associated with higher risk of SAH.CONCLUSIONS: The risk of SAH is 45% higher in women than in men, with substantial sex differences in risk factor strengths. In particular, a markedly stronger adverse effect of smoking in women may motivate targeted public health initiatives.
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| 30. |
- Wu, Hao, et al.
(författare)
-
The Gut Microbiota in Prediabetes and Diabetes: A Population-Based Cross-Sectional Study
- 2020
-
Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 32:3
-
Tidskriftsartikel (refereegranskat)abstract
- The link between the gut microbiota and type 2 diabetes (T2D) warrants further investigation because of known confounding effects from antidiabetic treatment. Here, we profiled the gut microbiota in a discovery (n = 1,011) and validation (n = 484) cohort comprising Swedish subjects naive for diabetes treatment and grouped by glycemic status. We observed that overall gut microbiota composition was altered in groups with impaired glucose tolerance, combined glucose intolerance and T2D, but not in those with impaired fasting glucose. In addition, the abundance of several butyrate producers and functional potential for butyrate production were decreased both in prediabetes and T2D groups. Multivariate analyses and machine learning microbiome models indicated that insulin resistance was strongly associated with microbial variations. Therefore, our study indicates that the gut microbiota represents an important modifiable factor to consider when developing precision medicine approaches for the prevention and/or delay of T2D.
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| 31. |
- Öhrfelt Olsson, Annika, 1973, et al.
(författare)
-
Cerebrospinal fluid alpha-synuclein in neurodegenerative disorders-a marker of synapse loss?
- 2009
-
Ingår i: Neuroscience letters. - : Elsevier BV. - 0304-3940. ; 450:3, s. 332-5
-
Tidskriftsartikel (refereegranskat)abstract
- The association of alpha-synuclein (alpha-syn) neuropathology with Parkinson's disease (PD) and several related disorders has led to an intense research effort to develop cerebrospinal fluid (CSF)- or blood-based alpha-syn biomarkers for these types of diseases. Recent studies show that alpha-syn is present in CSF and possible to measure using enzyme-linked immunosorbent assay (ELISA). Here, we describe a novel ELISA that allows for quantification of alpha-syn in CSF down to 50pg/mL. The diagnostic value of the test was assessed using CSF samples from 66 Alzheimer's disease (AD) patients, 15PD patients, 15 patients with dementia with Lewy bodies (DLB) and 55 cognitively normal controls. PD and DLB patients and controls displayed similar CSF alpha-syn levels. AD patients had significantly lower alpha-syn levels than controls (median [inter-quartile range] 296 [234-372] and 395 [298-452], respectively, p<0.001). Moreover, AD patients with mini-mental state examination (MMSE) scores below 20 had significantly lower alpha-syn than AD patients with MMSE scores of 20 or higher (p=0.02). There was also a tendency towards a negative correlation between alpha-syn levels and disease duration in the AD group (r=-0.247, p=0.06). Altogether, our results speak against CSF alpha-syn as a reliable biomarker for PD and DLB. The lower alpha-syn levels in AD, as well as the association of alpha-syn reduction with AD severity, approximated by MMSE, suggests that it may be a general marker of synapse loss, a hypothesis that warrants further investigation.
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| 32. |
- Öhrfelt Olsson, Annika, 1973, et al.
(författare)
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Identification of Novel α-Synuclein Isoforms in Human Brain Tissue by using an Online NanoLC-ESI-FTICR-MS Method.
- 2011
-
Ingår i: Neurochemical research. - : Springer Science and Business Media LLC. - 1573-6903 .- 0364-3190. ; 36:11, s. 2029-2042
-
Tidskriftsartikel (refereegranskat)abstract
- Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn(1-140)) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn(1-139) and Ac-α-syn(1-103)) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).
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| 33. |
- Öhrfelt Olsson, Annika, 1973, et al.
(författare)
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Screening for new biomarkers for subcortical vascular dementia and Alzheimer's disease
- 2011
-
Ingår i: Dementia and Geriatric Cognitive Disorders Extra. - : S. Karger AG. - 1664-5464. ; 1:1, s. 31-42
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Novel biomarkers are important for identifying as well as differentiating subcortical vascular dementia (SVD) and Alzheimer’s disease (AD) at an early stage in the disease process. Methods: In two independent cohorts, a multiplex immunoassay was utilized to analyze 90 proteins in cerebrospinal fluid (CSF) samples from dementia patients and patients at risk of developing dementia (mild cognitive impairment). Results: The levels of several CSF proteins were increased in SVD and its incipient state, and in moderate-to-severe AD compared with the control group. In contrast, some CSF proteins were altered in AD, but not in SVD. The levels of heart-type fatty acid binding protein (H-FABP) were consistently increased in all groups with dementia but only in some of their incipient states. Conclusions: In summary, these results support the notion that SVD and AD are driven by different pathophysiological mechanisms reflected in the CSF protein profile and that H-FABP in CSF is a general marker of neurodegeneration
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| 34. |
- Abdeljaber, Osama, et al.
(författare)
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Automatic estimation of annual ring profiles in Norway spruce timber boards using optical scanning and deep learning
- 2023
-
Ingår i: Computers & structures. - : Elsevier. - 0045-7949 .- 1879-2243. ; 275
-
Tidskriftsartikel (refereegranskat)abstract
- In softwood species, annual ring width correlates with various timber characteristics, including the density and modulus of elasticity along with bending and tensile strengths. Knowledge of annual ring profiles may contribute to more accurate machine strength grading of sawn timber. This paper proposes a fast and accurate method for automatic estimation of ring profiles along timber boards on the basis of optical scanning. The method utilizes two 1D convolutional neural networks to determine the pith location and detect the surface annual rings at multiple cross-sections along the scanned board. The automatically extracted rings and pith information can then be used to estimate the annual ring profile at each cross-section. The proposed method was validated on a large number of board cross-sections for which the pith locations and radial ring width profiles had been determined manually. The paper also investigates the potential of using the automatically estimated average ring width as an indicating property in machine strength grading of sawn timber. The results indicated that combining the automatically estimated ring width with other prediction variables can improve the accuracy of bending and tensile strength predictions, especially when the grading is based only on information extracted from optical and laser scanning data.(C) 2022 The Author(s). Published by Elsevier Ltd.
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| 35. |
- Alping, Peter, et al.
(författare)
-
Cancer Risk for Fingolimod, Natalizumab, and Rituximab in Multiple Sclerosis Patients
- 2020
-
Ingår i: Annals of Neurology. - : John Wiley & Sons. - 0364-5134 .- 1531-8249. ; 87:5, s. 688-699
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Novel, highly effective disease-modifying therapies have revolutionized multiple sclerosis (MS) care. However, evidence from large comparative studies on important safety outcomes, such as cancer, is still lacking.METHODS: In this nationwide register-based cohort study, we linked data from the Swedish MS register to the Swedish Cancer Register and other national health care and census registers. We included 4,187 first-ever initiations of rituximab, 1,620 of fingolimod, and 1,670 of natalizumab in 6,136 MS patients matched for age, sex, and location to 37,801 non-MS general population subjects. Primary outcome was time to first invasive cancer.RESULTS: We identified 78 invasive cancers among treated patients: rituximab 33 (incidence rate [IR] per 10,000 person-years = 34.4, 95% confidence interval [CI] = 23.7-48.3), fingolimod 28 (IR = 44.0, 95% CI = 29.2-63.5), and natalizumab 17 (IR = 26.0, 95% CI = 15.1-41.6). The general population IR was 31.0 (95% CI = 27.8-34.4). Adjusting for baseline characteristics, we found no difference in risk of invasive cancer between rituximab, natalizumab, and the general population but a possibly higher risk with fingolimod compared to the general population (hazard ratio [HR] = 1.53, 95% CI = 0.98-2.38) and rituximab (HR = 1.68, 95% CI = 1.00-2.84).INTERPRETATION: In this first large comparative study of 3 highly effective MS disease-modifying therapies, no increased risk of invasive cancer was seen with rituximab and natalizumab, compared to the general population. However, there was a borderline-significant increased risk with fingolimod, compared to both the general population and rituximab. It was not possible to attribute this increased risk to any specific type of cancer, and further studies are warranted to validate these findings.
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| 36. |
- Alping, Peter, et al.
(författare)
-
Validation of the Swedish Multiple Sclerosis Register Further Improving a Resource for Pharmacoepidemiologic Evaluations
- 2019
-
Ingår i: Epidemiology. - : Lippincott Williams & Wilkins. - 1044-3983 .- 1531-5487. ; 30:2, s. 230-233
-
Tidskriftsartikel (refereegranskat)abstract
- The Swedish Multiple Sclerosis Register is a national register monitoring treatment and clinical course for all Swedish multiple sclerosis (MS) patients, with high coverage and close integration with the clinic. Despite its great value for epidemiologic research, it has not previously been validated. In this brief report, we summarize a large validation of >3,000 patients in the register using clinical chart review in the context of the COMBAT-MS study. While further improving the data quality for a central cohort of patients available for future epidemiologic research, this study also allowed us to estimate the accuracy and completeness of the register data.
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| 37. |
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| 38. |
- Bergström, Petra, et al.
(författare)
-
Amyloid precursor protein expression and processing are differentially regulated during cortical neuron differentiation
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Amyloid precursor protein (APP) and its cleavage product amyloid beta (A beta) have been thoroughly studied in Alzheimer's disease. However, APP also appears to be important for neuronal development. Differentiation of induced pluripotent stem cells (iPSCs) towards cortical neurons enables in vitro mechanistic studies on human neuronal development. Here, we investigated expression and proteolytic processing of APP during differentiation of human iPSCs towards cortical neurons over a 100-day period. APP expression remained stable during neuronal differentiation, whereas APP processing changed. alpha-Cleaved soluble APP (sAPP alpha) was secreted early during differentiation, from neuronal progenitors, while beta-cleaved soluble APP (sAPP beta) was first secreted after deep-layer neurons had formed. Short A beta peptides, including A beta 1-15/16, peaked during the progenitor stage, while processing shifted towards longer peptides, such as A beta 1-40/42, when post-mitotic neurons appeared. This indicates that APP processing is regulated throughout differentiation of cortical neurons and that amyloidogenic APP processing, as reflected by A beta 1-40/42, is associated with mature neuronal phenotypes.
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| 39. |
- Blyberg, Louise, 1983-, et al.
(författare)
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Fire exposed light-frame timber walls : A study on the effect of geometrical reduction of a vertically loaded I-section stud
- 2009
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A wooden I-stud as a member of a light-frame timber wall is modelled with reducing flange width to simulate fire exposure. The stud is loaded with a vertical load and the effect of restraints from one gypsum board and the top and bottom rail is considered. Geometry and material values are chosen to correspond to a stud with flanges of solid wood and web of OSB (oriented strand board). A model with shell and beam elements is implemented in Abaqus. A buckling analysis is performed on a perfectly straight stud and then a geometrically nonlinear analysis is performed on a stud with an initial curvature. Both the buckling analysis and the geometrically nonlinear analysis show that even a large reduction of the flange width results only in moderate changes of the load-carrying capacity of the structure. In the report diagrams are presented from the geometrically nonlinear analysis where the critical load is easy to read once a failure stress is determined, but an estimate of the the failure stress is not given here.
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| 40. |
- Briggert, Andreas, 1984-, et al.
(författare)
-
Evaluation of three dimensional fibre orientation in Norway spruce using a laboratory laser scanner
- 2016
-
Ingår i: WCTE 2016. - Vienna : Vienna University of Technology. - 9783903039001
-
Konferensbidrag (refereegranskat)abstract
- This paper addresses laser scanning and utilization of the tracheid effect for determination of local fibre orientation, which is decisive for strength and stiffness of timber. A newly developed laboratory laser scanner that can be used for high resolution and high precision scanning of wood surfaces is used for in-depth assessment of a single Norway spruce specimen that contains a knot. It is assumed that the specimen has a plane of symmetry, through the knot, and by splitting the specimen in two parts it is possible to determine fibre orientation on orthogonal planes. Hence, by relying on the assumption of symmetry, the fibre orientation in 3D space can also be determined. The results are used to evaluate the possibility of utilizing the tracheid effect for determination of the out-of-plane fibre angle of an investigated surface. Furthermore, the results are used for verification of a theoretical fibre orientation model that has often been used by researchers.
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| 41. |
- Briggert, Andreas, et al.
(författare)
-
Modelling 3D orientation of knots in timber on the basis of dot laser scanning and the tracheid effect
- 2015
-
Konferensbidrag (refereegranskat)abstract
- Ongoing research concerns the possibility of determining the 3D orientation of wood fibres within the entire volume of a wooden board using surface information from laser scanning. Previous research, Olsson and Oscarsson [1], has shown that the fibre orientation of side boards can be determined on the basis of such information. The present research is extended to also comprise boards cut from the centre of the log and a first step in this work is to establish 3D models of knots in boards on the basis of information from dot laser scanning of surfaces.In comparison with other approaches aiming at 3D models of knots and wood fibre orientation, e.g. Guindos and Guaita[2] and Hackspiel et al. [3], the present model relies to a larger extent on the actual fibre orientation measured on each individual board, rather than on general assumption and mathematical models of typical fibre orientation alone. The fact that all data needed for the model can be sampled in sawmill production speed means that developed models could be used as a basis for advanced strength grading methods, for grading with respect to shape stability and for other purposes of industrial interest.
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| 42. |
- Briggert, Andreas, 1984-
(författare)
-
Modelling and strength grading of structural timber and glulam lamellae on the basis of optical scanning and dynamic excitation
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Machine strength grading of sawn timber is a sawmill process in which density, modulus of elasticity (MOE) and bending or tensile strength are predicted such that the timber can be assigned to strength classes. The predictions of these properties are performed using one or several so-called indicating properties (IPs), which represent a board property, or combination of board properties, measured non-destructively. A limitation of today’s strength grading is that the IPs applied in the industry for prediction of strength, in general, are based on rather weak statistical relationships between IPs and strength properties, which in turn results in poor material utilisation. It is well known that the strength of sawn timber is associated with the presence of knots and their surrounding fibre disorientations. Local fibre direction at surfaces of softwood can be determined by means of the light scattering that occur when a wood surface is illuminated by a dot-laser, i.e. by application of the so-called tracheid effect. Lately, IPs based on such measurements have been developed, and some of the suggested IPs have a strong statistical relationship to bending strength. The purposes of the research presented in this thesis are to contribute with knowledge of possibilities and limitations of the tracheid effect and of data of fibre directions in the vicinity of knots, to evaluate if information of fibre directions at surfaces of Norway spruce sawn timber can be used to achieve a better material utilisation of glulam lamellae and finger-jointed timber, and to provide insight regarding the grading regulations in Europe. Results presented herein show that knots and fibre direction within the interior of boards can be modelled on the basis of data obtained by means of the tracheid effect, but also that a previously proposed method to determine out-of-plane fibre angles gives poor accuracy. As regards grading of glulam lamellae, an IP based on fibre directions and dynamic MOE is proposed for prediction of tensile strength. The latter is used when grading glulam lamellae. Application of the proposed IP resulted in substantially increased yield in strength classes. It is also shown that this IP is applicable for boards with sawn as well as with planed surface finish. Regarding current regulations for machine strength grading in Europe, results indicate that grading based on global board properties give higher yield than what is appropriate.
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| 43. |
- Briggert, Andreas, 1984-, et al.
(författare)
-
Prediction of tensile strength of sawn timber : models for calculation of yield in strength classes
- 2020
-
Ingår i: Materials and Structures. - : Springer. - 1359-5997 .- 1871-6873. ; 53:3, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- In Europe, strength classes for structural timber and glulam lamellae are defined by minimum requirements of characteristic values of the grade determining properties (GDPs). To fulfill these minimum requirements of characteristic values in the daily production at sawmills, indicating properties (IPs) to GDPs are calculated for each board and based on predetermined limits of the IPs (settings) boards are assigned to the graded class, or rejected. The aims of this paper is to address and discuss two different grading procedures/models that can be applied when settings for IPs that reflects a local board property are derived and to show how the yield in different T-classes depend on the model applied. It is not always that a board’s weakest cross-section is evaluated in a destructive test. An IP representing a local board property can therefore be determined either as the lowest property of the tested part of the board or as the lowest property along the whole board when applied to derive settings. Results presented in this paper show that too low settings and too large yields are obtained when the latter IP is employed. Similarly, IPs reflecting a global board property, like axial dynamic MOE, also give too low settings and too high yield in strength classes. This paper is the second and closing part of a series of two paper on prediction of GDPs and procedures for grading sawn timber into T-classes.
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| 44. |
- Briggert, Andreas, 1984-, et al.
(författare)
-
Prediction of tensile strength of sawn timber : definitions and performance of indicating properties based on surface laser scanning and dynamic excitation
- 2020
-
Ingår i: Materials and Structures. - : Springer. - 1359-5997 .- 1871-6873. ; 53:3, s. 1-20
-
Tidskriftsartikel (refereegranskat)abstract
- The presence of wood irregularities such as knots are decisive for the mechanical properties of sawn timber, and efficient utilisation of timber requires methods by which grade determining properties can be predicted with high accuracy. In the glulam and sawmilling industries today, there is a potential and a need for more accurate prediction methods. This paper concerns the performance of a set of indicating properties calculated by means of data from surface laser scanning, dynamic excitation and X-ray scanning, the latter used to obtain boards’ average density. A total number of 967 boards of Norway spruce originating from Finland, Norway and Sweden were used to determine statistical relationships between the indicating properties and the grade determining properties used to grade sawn timber into T-classes. Results show that the indicating properties give coefficients of determination to tensile strength as high as 0.70. Furthermore, results also show that laser scanning of boards with sawn surface finish give basis for almost as accurate grading as what scanning of planed boards do. The results imply that more accurate grading of timber into T-classes is possible by application of a new set of indicating properties. This paper is part one of a series of two papers. In the second paper, two models to derive settings and calculate yield in different strength classes using the indicating properties presented herein are compared and discussed.
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| 45. |
- Briggert, Andreas, 1984-, et al.
(författare)
-
Three dimensional knot models based on surface laser scanning
- 2015
-
Ingår i: Proceedings 19th International Nondestructive Testing and Evaluation of Wood Symposium Rio de Janeiro, Brazil, 23-25 September, 2015.. - Madison, USA : USDA, Forest Service, Forest Products Laboratory. ; , s. 83-90, s. 83-90
-
Konferensbidrag (refereegranskat)abstract
- Most machine strength grading methods of today result in limited grading accuracy and poor yield in higher strength classes. A new and more accurate grading method utilizing laser scanning technique to determine the in-plane fibre directions on board surfaces was recently approved for the European market. In this, however, no consideration is taken to the out-of-plane direction of the fibres. A first step towards scanning-based 3D models of the fibre orientation is the establishment of 3D knot models. In this investigation laser scanning was used to identify knot surfaces on longitudinal board surfaces. By means of developed algorithms knot surfaces that belonged to the same physical knot visible on different sides of the board were identified. All knots with surface areas larger than 100 mm2 were correctly identified and modeled in 3D. This is a promising starting point for further development of the new grading method based on laser scanning.
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| 46. |
- Briggert, Andreas, 1984-, et al.
(författare)
-
Tracheid effect scanning and evaluation of in-plane and out-of-plane fibre direction in Norway spruce using
- 2018
-
Ingår i: Wood and Fiber Science. - : Society of Wood Science and Technology. - 0735-6161. ; 50:4, s. 411-429
-
Tidskriftsartikel (refereegranskat)abstract
- Local fiber direction is decisive for both strength and stiffness in timber. In-plane fiber direction on surfaces of timber can be determined using the so-called tracheid effect which is frequently used in both research and industry applications. However, a similar established method does not exist for measuring the out-of-plane angle, also known as diving angle. The purposes of this article were to evaluate if the tracheid effect can also be used to determine, with reasonable accuracy, the out-of-plane angle in Norway spruce and to verify an existing mathematical model used to calculate the fiber direction in the vicinity of knots. A newly developed laboratory laser scanner was applied for assessment of fiber directions in a single Norway spruce specimen containing a knot. It was assumed that the specimen had a plane of symmetry through the center of the knot, and by splitting the specimen through this plane into two parts, it was possible to make measurements on orthogonal planes. The results showed that the out-of-plane angle could not be determined with very high accuracy and the difficulties related to this objective were analyzed. Regarding the mathematical model of fiber direction in the vicinity of a knot, fiber directions calculated on the basis of this model agreed well with experimentally obtained fiber directions, but successful application of the model requires that the geometry of the knot is known in detail.
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| 47. |
- Carlsson, Björn, 1958, et al.
(författare)
-
Differences in associations between HSD11B1 gene expression and metabolic parameters in subjects with and without impaired glucose homeostasis
- 2010
-
Ingår i: Diabetes Research and Clinical Practice. - : Elsevier BV. - 1872-8227 .- 0168-8227. ; 88:3, s. 252-258
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: Animal studies indicate a role for 11 beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) in the development of obesity. The association to glucose homeostasis is less clear. We investigated the relationship between HSD11B1 mRNA levels in adipose tissue and in skeletal muscle and anthropometric and metabolic measurements in humans with and without impaired glucose homeostasis. Methods: Twelve obese subjects with impaired glucose homeostasis (MetS+) and 12 obese controls (MetS-) received a Very Low Calorie Diet for 16 weeks and adipose tissue biopsies, blood samples and measurements were obtained. In a second cohort, skeletal muscle biopsies, blood samples and measurements were obtained from 18 subjects with type 2 diabetes (T2DM) and 17 subjects with normal glucose tolerance (NGT). Gene expression was measured by DNA microarray in both studies. Results: HSD11B1 mRNA levels were reduced during diet, and anthropometric measurements and metabolic parameters were associated with HSD11B1 mRNA levels in the MetS-group. However, in the MetS+ group these associations were lost or in opposite direction. This difference was also observed in skeletal muscle between T2DM and NGT. Conclusions: HSD11B1 mRNA levels are associated with metabolic parameters and anthropometric measurements in subjects with normal glucose homeostasis but not in subjects with impaired glucose homeostasis. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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| 48. |
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| 49. |
- Danielsson, Tatiana
(författare)
-
Further Investigations of Convergence Results for Homogenization Problems with Various Combinations of Scales
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on six papers. We study the homogenization of selected parabolic problems with one or more microscopic scales in space and time, respectively. The approaches are prepared by means of certain methods, like two-scale convergence, multiscale convergence and also the evolution setting of multiscale convergence and very weak multiscale convergence. Paper I treats a linear parabolic homogenization problem with rapid spatial and temporal oscillations in perforated domains. Suitable results of two-scale convergence type are established. Paper II deals with further development of compactness results which can be used in the homogenization procedure engaging a certain limit condition. The homogenization procedure deals with a parabolic problem with a certain matching between a fast spatial and a fast temporal scale and a coefficient passing to zero that the time derivative is multiplied with. Papers III and IV are further generalizations of Paper II and investigate homogenization problems with different types of matching between the microscopic scales. Papers III and IV deal with one and two rapid scales in both space and time respectively. Paper V treats the nonlinearity of monotone parabolic problems with an arbitrary number of spatial and temporal scales by applying the perturbed test functions method together with multiscale convergence and very weak multiscale convergence adapted to the evolution setting. In Paper VI we discuss the relation between two-scale convergence and the unfolding method and potential extensions of existing results. The papers above are summarized in Chapter 4. Chapter 1 gives a brief introduction to the topic and Chapters 2 and 3 are surveys over some important previous results.
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