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- Högberg, J. Li
(författare)
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Mixed mode cohesive law
- 2006
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Ingår i: International Journal of Fracture. - : Springer Netherlands. - 0376-9429 .- 1573-2673. ; 141:3-4, s. 549-559
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Tidskriftsartikel (refereegranskat)abstract
- A traction-separation relation to model the fracture process is presented. The cohesive law captures the linear elastic and softening behaviour prior to fracture. It also allows for different fracture parameters, such as fracture energy, strength and critical separation in different mode mixities. Thus, the fracture process in mode I (peel), in mode II (shear) or in mixed mode (a combination of peel and shear) can be modelled without the limitation of a common fracture energy in peel and shear. Examples are given in form of FE- implementations of the normalised cohesive law, namely for the Unsymmetrical Double Cantilever Beam (UDCB) specimen and the Mixed-mode double Cantilever Beam (MCB) specimen. Both specimens are adhesively bonded and loaded in mixed-mode
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| 4. |
- Granström, Pär
(författare)
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Flodpärlmusslan i Gävleborgs län
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Flodpärlmusslans fortsatta existens anses inte vara tryggad på sikt.Redan idag har den försvunnit från stora delar av Sverige och nästan helt från övriga Europa. I Sverige är flodpärlmusslan numera fridlyst. I framför allt Norrland finns dock ännu en del musselbestånd kvar. Detta gör att Gävleborgs län, tillsammans med övriga Norrlands län, har ett särskilt ansvar för flodpärlmusslans fortsatta existens.I Gävleborgs län har totalt 113 vattendrag med förekomst av flodpärlmussla påträffats och undersökts. nyrekrytering har kunnat konstaterats i 52 av dessa. Omfattningen av nyrekryteringen är dock oftast mycket liten. På 21 lokaler utgör de små musslorna 5% eller mer av det totala beståndet och på endast 12 lokaler utgör andelen småmusslor 10% eller mer av det totala antalet flodpärlmusslor.Riktigt små musslor, kortare än 10 mm, har endast påträffats i två av de undersökta vattendragen och musslor kortare än 20 mm i 13 av vattendragen. Detta kan delvis förklaras av att just dessa musslor oftast mer eller mindre befinner sig i själva bottensubstratet och inte går att se då man söker av bottnen med en vattenkikare.Därför kan man utgå från att de riktigt små musslorna är underrepresenterade i materialet.Från och med ungefär 30 mm storlek är det dock i stort sett lika lätt, eller svårt, att upptäcka musslorna.I 22 av de totalt 113 undersökta vattendragen observerades överhuvudtaget ingen mussla som var kortare än 100 mm vilket antagligen innebär att musselbestånden helt saknat nyrekrytering under flera decennier.Trots detta finns det ett antal vattendrag i länet som hyser större och mindre musselbestånd med vad man får betrakta som fungerande nyrekrytering.Nästa steg blir till att skydda dessa så att de kan fortleva. Dessutom måste det skapas förutsättningar för övriga musselbestånd att åretfå en nyrekrytering som inte leder till att de försvinner från vattendragen.Med hjälp av flodpärlmusslan som en indikator för goda förutsättningar för biologisk mångfald kan man även identifiera andra höga naturvärden i strömmande biotoper.
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| 5. |
- Grobe, K, et al.
(författare)
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Heparan sulfate and development : differential roles of the N-acetylglucosamine N-deacetylase/N-sulfotransferase isozymes.
- 2002
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - 0304-4165 .- 1872-8006. ; 1573:3, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfates (HSs) are N- and O-sulfated polysaccharide components of proteoglycans, which are important constituents of the cell surface as well as the extracellular matrix. Heparin, with extensive clinical application as an anticoagulant, is a highly sulfated form of HS present within the granules of connective tissue type mast cells. The diverse functions of HS, which include the modulation of growth factor/cytokine activity, interaction with matrix proteins and binding of enzymes to cell surfaces, depend greatly on the presence of specific, high affinity regions on the chains. N-acetylglucosamine N-deacetylase/N-sulfotransferases, NDSTs, are an important group of enzymes in HS biosynthesis, initiating the sulfation of the polysaccharide chains and thus determining the generation of the high affinity sites. Here, we review the role of the four vertebrate NDSTs in HS biosynthesis as well as their regulated expression. The main emphasis is the phenotypes of mice lacking one or more of the NDSTs.
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| 7. |
- Haller, Sven, et al.
(författare)
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PET amyloid in normal aging : direct comparison of visual and automatic processing methods
- 2020
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Ingår i: Scientific Reports. - : NATURE RESEARCH. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of amyloid deposits is a critical step for the identification of Alzheimer disease (AD) signature in asymptomatic elders. Whether the different amyloid processing methods impacts on the quality of clinico-radiological correlations is still unclear. We directly compared in 155 elderly controls with extensive neuropsychological testing at baseline and 4.5 years follow-up three approaches: (i) operator-dependent standard visual reading, (ii) operator-independent automatic SUVR with four different reference regions, and (iii) novel operator and region of reference-independent automatic A beta-index. The coefficient of variance was used to examine inter-individual variability for each processing method. Using visually-established amyloid positivity as the gold standard, the area under the receiver operating characteristic curve (ROC) was computed. Linear regression models were used to assess the association between changes in continuous cognitive score and amyloid uptake values. In SUVR analyses, the coefficient of variance varied from 1.718 to 1.762 according to the area of reference and was of - 3.045 for the A beta-index method. Compared to the visual rating, A beta-index method showed the largest area under the ROC curve [0.9568 (95% CI 0.9252, 0.98833)]. The best cut-off score was of - 0.3359 with sensitivity and specificity values of 0.97 and 0.83, respectively. Only the A beta-index was related to more severe decrement of cognitive performances [regression coefficient: 9.103 (95% CI 1.148, 17.058)]. The A beta-index is considered as preferred option in asymptomatic elders, since it is operator-independent, avoids the selection of reference area, is closer to established visual scoring and correlates with the evolution of cognitive performances.
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| 9. |
- Högberg, Jonas, 1976, et al.
(författare)
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Increased absorbed liver dose in Selective Internal Radiation Therapy (SIRT) correlates with increased sphere-cluster frequency and absorbed dose inhomogeneity
- 2015
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Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The higher tolerated mean absorbed dose for selective internal radiation therapy (SIRT) with intra-arterially infused 90Y microspheres compared to external beam therapy is speculated to be caused by absorbed dose inhomogeneity, which allows for liver regeneration. However, the complex liver microanatomy and rheology makes modelling less valuable if the tolerance doses are not based on the actual microsphere distribution. The present study demonstrates the sphere distribution and small-scale absorbed dose inhomogeneity and its correlation with the mean absorbed dose in liver tissue resected after SIRT. Methods A patient with marginally resectable cholangiocarcinoma underwent SIRT 9 days prior to resection including adjacent normal liver tissue. The resected specimen was formalin-fixed and sliced into 1 to 2-mm sections. Forty-one normal liver biopsies 6-8 mm in diameter were punched from these sections and the radioactivity measured. Sixteen biopsies were further processed for detailed analyses by consecutive serial sectioning of 15 30-μm sections per biopsy, mounted and stained with haematoxylin-eosin. All sections were scrutinised for isolated or conglomerate spheres. Small-scale dose distributions were obtained by applying a 90Y-dose point kernel to the microsphere distributions. Results A total of 3888 spheres were found in the 240 sections. Clusters were frequently found as strings in the arterioles and as conglomerates in small arteries, with the largest cluster comprising 453 spheres. An increased mean absorbed dose in the punch biopsies correlated with large clusters and a greater coefficient of variation. In simulations the absorbed dose was 5–1240 Gy; 90% were 10-97 Gy and 45% were <30 Gy, the assumed tolerance in external beam therapy. Conclusions Sphere clusters were located in both arterioles and small arteries and increased in size with increasing sphere concentration, resulting in increased absorbed dose inhomogeneity, which contradicts earlier modelling studies.
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| 10. |
- Högberg, Karl-Anders, et al.
(författare)
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Field performance of Pinus contorta trees propagated vegetatively via adventitious buds
- 2005
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 20:4, s. 318-321
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Tidskriftsartikel (refereegranskat)abstract
- Pinus contorta plants regenerated from adventitious buds induced on zygotic embryos were planted in a field trial where growth, straightness and flowering were followed over 7 years. Seedlings were taller than the plants derived from adventitious buds at the start of the field trial. Adventitious plants did not catch up with seedlings in height after 7 years in the field, but the relative height growth was equal. The higher frequency of plagiotropic growth that was displayed by adventitious plants the first year in the field was not reflected by differences in the frequency of basal sweeps 6 years later. However, the frequency of crooked stems was comparatively high but similar among the plant types. Flowering was more abundant for the seedlings than for adventitious plants. Taken together, the results show that P. contorta can be cloned via adventitious buds from zygotic embryos, and that the resulting plants show satisfactory growth for inclusion in breeding.
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