| 1. |
- Rönnegård, Lars, et al.
(författare)
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Modelling dominance in a flexible intercross analysis
- 2009
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Ingår i: BMC Genetics. - : Springer Science and Business Media LLC. - 1471-2156. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Conclusion: We have extended FIA to include QTL dominance effects. The power of FIA was superior, or similar, to standard regression methods for QTL effects with dominance. The difference in power for FIA with or without dominance is expected to be small as long as the QTL effects are not overdominant. We suggest that FIA with only additive effects should be the standard model to be used, especially since it is more computationally efficient.
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| 2. |
- Rönnegård, Lars, et al.
(författare)
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Non-iterative variance component estimation in QTL analysis
- 2009
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Ingår i: Journal of Animal Breeding and Genetics. - : Wiley. - 0931-2668 .- 1439-0388. ; 126:2, s. 110-116
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Tidskriftsartikel (refereegranskat)abstract
- In variance component quantitative trait loci (QTL) analysis, a mixed model is used to detect the most likely chromosome position of a QTL. The putative QTL is included as a random effect and a method is needed to estimate the QTL variance. The standard estimation method used is an iterative method based on the restricted maximum likelihood (REML). In this paper, we present a novel non-iterative variance component estimation method. This method is based on Henderson's method 3, but relaxes the condition of unbiasedness. Two similar estimators were compared, which were developed from two different partitions of the sum of squares in Henderson's method 3. The approach was compared with REML on data from a European wild boar x domestic pig intercross. A meat quality trait was studied on chromosome 6 where a functional gene was known to be located. Both partitions resulted in estimated QTL variances close to the REML estimates. From the non-iterative estimates, we could also compute good approximations of the likelihood ratio curve on the studied chromosome.
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| 3. |
- Blomberg, Jonas, et al.
(författare)
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An algorithm for comparing density in CT-images taken before and after compression of Pinus sylvestris
- 2005
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Ingår i: European Journal of Wood and Wood Products. - : Springer Science and Business Media LLC. - 0018-3768 .- 1436-736X. ; 63:1, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Ten plain-sawn boards of Scots pine (Pinus sylvestris L.) were compressed semi-isostatically according to the CaLignum process in a Quintus press at 25°C and 140 MPa. X-ray computerised tomography images of the same cross-sections were captured before and after compression and compared using a transformation algorithm. In the algorithm the shape of compressed cross-sections were converted to the same shape as non-compressed using the density variation between pixels. Density after compression and the increase in density were analysed using PLS regression. The regressor variables described position in the cross-section and wood properties of each pixel. Heartwood and other resinous wood were less compressed than sapwood, particularly in boards with high resin content. Density also increased little close to the press table, especially in whorls with large knots. Higher original density gives lower degree of compression but still higher density after compression. © Springer-Verlag 2005
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| 4. |
- Blomberg, Jonas
(författare)
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Elastic strain at semi-isostatic compression of Scots pine (Pinus sylvestris)
- 2005
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Ingår i: Journal of Wood Science. - : Springer Science and Business Media LLC. - 1435-0211 .- 1611-4663. ; 51:4, s. 401-404
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Tidskriftsartikel (refereegranskat)abstract
- Quarter-sawn and plain-sawn specimens of Scots pine were semi-isostatically compressed at 5, 15, 50, and 140MPa in a Quintus press. Elastic strain was measured using a telescope device that was pushed together when wood was compressed and remained in this position at release of pressure. Delayed elastic and plastic strains were assessed through repeated callipering during 5 years after densification. At 140MPa, wood reached an almost compact structure (ρ ≈ 1450kg/m3) but as a result of elastic springback the density decreased to just below 1000kg/m3. At 140MPa, the elastic and delayed elastic strains were 14.6% and 1.8%, respectively, in quarter-sawn specimens, and were 13.1% and 0.8%, respectively, in plain-sawn specimens. The higher elastic strains in quarter-sawn specimens can be attributed to elastic springback in the tangentially deformed latewood bands
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| 5. |
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| 6. |
- Blomberg, Jonas, et al.
(författare)
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Swelling pressure of semi-isostatically densified wood under different mechanical restraints
- 2007
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Ingår i: Wood Science and Technology. - : Springer Science and Business Media LLC. - 0043-7719 .- 1432-5225. ; 41:5, s. 401-415
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Tidskriftsartikel (refereegranskat)abstract
- Semi-isostatically densified and native wood samples of Scots pine and European birch were soaked in water. The swelling coefficients as well as the swelling pressure, that arose when the specimens were restrained in some way prior to the swelling, were measured using a universal testing machine equipped with a high resolution load-cell and an external extensometer. As densified wood swells, the native structure is almost restored and the swelling pressure became twice as high as for native wood in the most compressed directions (radial for pine and birch). That cell-shape recovery increases the swelling pressure can explain the problems with imbalance in laminated constructions where densified wood is used. The possibility to predict the swelling pressure from basic material properties was evaluated. The correlations between swelling pressure and material properties were strong enough to yield good predictive models
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| 7. |
- Boonstra, M.J., et al.
(författare)
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Semi-isostatic densification of heat-treated radiata pine
- 2007
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Ingår i: Wood Science and Technology. - : Springer Science and Business Media LLC. - 0043-7719 .- 1432-5225. ; 41:7, s. 607-617
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Tidskriftsartikel (refereegranskat)abstract
- Semi-isostatic densification is a useful method to increase the density and to improve the mechanical properties of fast-grown softwood species like radiata pine. A major disadvantage of this method is the almost complete recovery of the original dimensions when densified wood is exposed to moisture. Heat treatment improves the dimensional stability of wood and might be a useful method to prevent this shape-recovery after densification. However, no or only a limited effect on the shape-recovery was found when densified radiata pine was exposed to moisture.
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| 8. |
- Danielsson, Marie, et al.
(författare)
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Mini-seedlings of Picea abies are less attacked by Hylobius abietis than conventional ones : Is plant chemistry the explanation?
- 2008
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 23:4, s. 299-306
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Tidskriftsartikel (refereegranskat)abstract
- The pine weevil, Hylobius abietis (L.), is a major pest in conifer reforestation areas in the Palaearctic region. Size and chemistry of the seedlings may explain the damage rates in plantations. The performance of 10-week containerized seedlings (mini-seedlings) was compared with 1-year-old conventional seedlings of Norway spruce, Picea abies (L.), in a field experiment in central Sweden. After 2 years the weevil damage was lower for the mini-seedlings than for the conventional seedlings (3.5 vs 55%). After 3 years, the overall survival was 82 and 75%, respectively. Weevil damage was the main cause of mortality for conventional seedlings, whereas mini-seedlings mainly died from drought. Volatiles of the two seedling types were compared by solid-phase microextraction-gas chromatography -mass spectrometry (SPME-GC-MS). Unwounded mini-seedlings and conventional seedlings differed in their compositions of monoterpenes and sesquiterpenes. Miniseedlings mainly emitted limonene, known to be repellent to the pine weevil. When wounded, green leaf volatiles were released by mini-seedlings while the pine weevil attractant alpha-pinene was released by conventional seedlings. Volatiles may partly explain the mini-seedlings' resistance against weevil attack. Further studies are needed to clarify how long this miniseedling effect remains.
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| 9. |
- Gullberg, Tomas, et al.
(författare)
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A method for integrated extraction of logging residues and soil scarification on a small scale
- 2006
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 30:12, s. 1035-1042
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Tidskriftsartikel (refereegranskat)abstract
- A new method for integrated haulage of logging residues and soil scarification on a small-scale has been evaluated. The base machine was a farm tractor to which a grapple loader trailer was attached. The grapple loader had an attachment on the grapple used for the integrated recovery of forest energy from logging residues and soil scarification. The machine was in this case, when hauling the logging residues fresh, also used for hauling round wood. It may even be used for, e.g. spreading wood ashes (only simulated). Conventional machine systems with special machines for all four types of work result in very high fixed costs for moving, etc. which makes cost unacceptable for many small sites. Effective time per dry ton of logging residues was 28.4min in the integrated method, of which soil scarification was 14.3min. Average load size was about 1.3ton dry matter (about 2.9m3 solid). The soil scarification plots covered 12% of the surface. Cost calculations show that the integration of several activities results in substantially lower costs for small harvesting sites. For sites of about 1.5ha the cost is about the same as for conventional machines. The studied method creates new possibilities for self-employed forest owners to do the work themselves and, in case of lower personal cost and no moving cost, reduce cost further.
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| 10. |
- Joosen, R.V.L., et al.
(författare)
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Correlating gene expression to physiological parameters and environmental conditions during cold acclimation of Pinus sylvestris, identification of molecular markers using cDNA microarrays
- 2006
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Ingår i: Tree Physiology. - : Oxford University Press (OUP). - 0829-318X .- 1758-4469. ; 26:10, s. 1297-1313
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Tidskriftsartikel (refereegranskat)abstract
- Scots pine (Pinus sylvestris L.) seedlings were grown under different conditions (three field locations, two seasons and two climate room regimes), and then analyzed for freezing tolerance of shoots and roots and for transcript abundance in apical buds based on a cDNA microarray containing about 1500 expressed sequence tags (ESTs) from buds of cold-treated Scots pine seedlings. In a climate room providing long daily photoperiods and high temperatures, seedlings did not develop freezing tolerance, whereas seedlings in a climate room set to provide declining temperatures and day lengths developed moderate freezing tolerance. Control seedlings grown outside under field conditions developed full freezing tolerance. Differences in physiological behavior of the different seedling groups, combined with molecular analysis, allowed identification of a large group of genes, expression of which changed during the development of freezing tolerance. Transcript abundance of several of these genes was highly correlated with freezing tolerance in seedlings differing in provenance, field location or age, making them excellent candidate marker genes for molecular tests for freezing tolerance.
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