| 1. |
- Tuskan, G A, et al.
(author)
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The genome of black cottonwood, Populus trichocarpa (Torr. & Gray).
- 2006
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In: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 313:5793, s. 1596-604
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Journal article (peer-reviewed)abstract
- We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
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| 2. |
- Axelsson, Petter, et al.
(author)
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Leaf ontogeny interacts with Bt modification to affect innate resistance in GM aspens
- 2011
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In: Chemoecology. - : Springer Science and Business Media LLC. - 0937-7409 .- 1423-0445. ; 21:3, s. 161-169
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Journal article (peer-reviewed)abstract
- Bioassays with a non-target slug (Deroceras spp.) and chemical analyses were conducted using leaf tissue from already existing genetically modified insect-resistant aspen trees to examine whether genetic modifications to produce Bacillus thuringiensis (Bt) toxins could affect plant phytochemistry, which in turn might influence plant-herbivore interactions. Three major patterns emerged. First, two independent modifications for Bt resistance affected the phytochemical profiles of leaves such that both were different from the isogenic wild-type (Wt) control leaves, but also different from each other. Among the contributors to these differences are substances with a presumed involvement in resistance, such as salicortin and soluble condensed tannins. Second, bioassays with one Bt line suggest that the modification somehow affected innate resistance ("Innate" is used here in opposition to the "acquired" Bt resistance) in ways such that slugs preferred Bt over Wt leaves. Third, the preference test suggests that the innate resistance in Bt relative to Wt plants may not be uniformly expressed throughout the whole plant and that leaf ontogeny interacts with the modification to affect resistance. This was manifested through an ontogenetic determined increase in leaf consumption that was more than four times higher in Bt compared to Wt leaves. Our result are of principal importance, as these indicate that genetic modifications can affect innate resistance and thus non-target herbivores in ways that may have commercial and/or environmental consequences. The finding of a modification-ontogeny interaction effect on innate resistance may be especially important in assessments of GM plants with a long lifespan such as trees.
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| 3. |
- Fluck, M., et al.
(author)
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Comparison of potential flow-based and measured pressure distributions over upwind sails
- 2010
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In: Journal of Aircraft. - : American Institute of Aeronautics and Astronautics Inc.. - 0021-8669 .- 1533-3868. ; 47:6, s. 2174-2176
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Journal article (peer-reviewed)abstract
- The results of the comparative analysis of potential flow-based and measured pressure distributions over upwind sails were investigated. The sail models were supported by wires inside a frame, rather than being set on a yacht model that allowed trimming the models to several predefined positions very precisely and with good repeatability. The freestream dynamic pressure was q = 32.5 Pa, with a variation of ±1 Pa in the vicinity of the sails. The headsail and its image were considered to be one sail with a continuous deck-symmetrical circulation distribution. The vortex-lattice method (VLM) code uses mirror images of the sails to model the influence of the sea surface. The results indicated that the mast and hull, which are ignored in the theoretical analysis, lead to only a 3% reduction in lift of the headsail, but to a 7% reduction for the mainsail.
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| 4. |
- Hjältén, Joakim, et al.
(author)
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Increased Resistance of Bt Aspens to Phratora vitellinae (Coleoptera) Leads to Increased Plant Growth under Experimental Conditions
- 2012
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In: PLOS ONE. - : Public library science. - 1932-6203. ; 7:1
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Journal article (peer-reviewed)abstract
- One main aim with genetic modification (GM) of trees is to produce plants that are resistant to various types of pests. The effectiveness of GM-introduced toxins against specific pest species on trees has been shown in the laboratory. However, few attempts have been made to determine if the production of these toxins and reduced herbivory will translate into increased tree productivity. We established an experiment with two lines of potted aspens (Populus tremulaxPopulus tremuloides) which express Bt (Bacillus thuringiensis) toxins and the isogenic wildtype (Wt) in the lab. The goal was to explore how experimentally controlled levels of a targeted leaf beetle Phratora vitellinae (Coleoptera; Chrysomelidae) influenced leaf damage severity, leaf beetle performance and the growth of aspen. Four patterns emerged. Firstly, we found clear evidence that Bt toxins reduce leaf damage. The damage on the Bt lines was significantly lower than for the Wt line in high and low herbivory treatment, respectively. Secondly, Bt toxins had a significant negative effect on leaf beetle survival. Thirdly, the significant decrease in height of the Wt line with increasing herbivory and the relative increase in height of one of the Bt lines compared with the Wt line in the presence of herbivores suggest that this also might translate into increased biomass production of Bt trees. This realized benefit was context-dependent and is likely to be manifested only if herbivore pressure is sufficiently high. However, these herbivore induced patterns did not translate into significant affect on biomass, instead one Bt line overall produced less biomass than the Wt. Fourthly, compiled results suggest that the growth reduction in one Bt line as indicated here is likely due to events in the transformation process and that a hypothesized cost of producing Bt toxins is of subordinate significance.
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| 5. |
- Pilate, J., et al.
(author)
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Development of a three-dimensional inverse sail design method
- 2008
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In: 3rd High Performance Yacht Design Conference 2008, HPYD 2008. - 9781622769124 ; , s. 257-265
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Conference paper (peer-reviewed)abstract
- A code which generates the camber shape of a sail from a desired sail plan-form, sail twist distribution and surface pressure map has been written. This is an iterative 3D inverse sail design code. The method initially uses inverse thin aerofoil theory, applies this to the desired pressure map and creates an initial sail shape. A theory which gives a relationship between the change in the pressure map and the change in the sail camber was developed and is described. The code applies that theory to the difference between the desired pressure map and the pressure map of the initial sail shape. The calculated camber difference is added to the initial shape to give an improved shape with a pressure distribution closer to the desired one. This process is repeated until the generated sail produces the desired pressure map. Validation tests were performed by generating a pressure distribution from a known sail shape using a VLM code, and then the method described in the paper was used to find the shape from the pressure distribution. The sail shape was successfully obtained in as few as five iterations, with a maximum error of only about 0.2 % of the sail chord, which is acceptable in sail design practice.
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| 6. |
- Pilate, J. P., et al.
(author)
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A three-dimensional inverse method for the design of sails
- 2016
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In: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - : Royal Institution of Naval Architects. - 1740-0694. ; 158, s. 73-87
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Journal article (peer-reviewed)abstract
- This paper investigates an inverse process for the design of yacht sails. The method is described and then applied to the design of optimal sails for a specific yacht The proposed inverse method generates the three-dimensional shapes of a headsail and mainsail from prescribed loading (i.e. differential pressure) distributions, accounts for the effect of the sea surface, and also simulates the twist and shear of the incoming flow. The uncoupled iterative routine solves a sequence of analysis steps so that the sail shapes are deformed in such a way that their updated loading distributions converge to the specified target distributions. During each iteration equations derived from two-dimensional Thin Aerofoil Theory, calculate a geometry correction from the difference between the current and target loading distributions. This correction is applied to the sail geometry, and a vortex lattice method code calculates the updated three-dimensional differential pressure distributions, which are again compared to the target distributions. Usually only five iterations are required to converge to sail shapes that have the target loading distributions. The inverse method has been validated by inverting the traditional way of analysing sails, i.e. a set of sails with known geometry has been analysed and the loading distributions on the headsail and mainsail were calculated. These distributions were then used as an input for the inverse code. It was found that the difference in camber between the original sails and the calculated geometry is less than 0.01% of camber at the mid-span of the sails. The second part of the paper presents two methods for the design of optimal sails for a yacht One of the methods uses the more traditional analysis approach, while the other employs the inverse method described in this paper. The optimisation is performed for a Transpac 52 yacht in 12 knots (6.5 m/s) of true wind speed to obtain the best velocity made good. Results from both methods are presented and discussed and it is found that the results in terms of boat speed are similar although the trims differ slightly. However, the new inverse method is approximately nine times faster than the traditional analysis approach.
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| 7. |
- Pilate, J. P., et al.
(author)
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A three-dimensional inverse sail design method
- 2010
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In: Transactions of the Royal Institution of Naval Architects Part B: International Journal of Small Craft Technology. - 1740-0694. ; 152:2, s. B107-B114
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Journal article (peer-reviewed)abstract
- Today sail shapes are usually designed using analysis methods i.e. based on experience the designer specifies a certain sail shape and then proceeds to determine the aerodynamic characteristics of this sail. Finding optimum sail shapes using such a method can involve a lot of trial and error. A new approach in sail design is proposed in this paper, where an inverse method is considered. The inverse method involves specifying the aerodynamic characteristics, and working backwards to obtain the corresponding sail shape to produce those characteristics. The paper investigates a single sail in an upwind condition. Because the solution of the inverse process is not unique, some variables have to be fixed. The sail shape is defined by three parameters: the planform, the camber, and the twist. In the present work, the planform is assumed to be defined by the class-rules of the yacht and is thus known. The sail designer has to specify one of the two possible trims: the twist or the camber. Then the theory, described in the paper, shows that there is a unique solution of the inverse process. Thus two cases are considered. The first involves a fixed twist and planform. There, the code generates the camber of the sail which will produce a given pressure distribution. The second case considers a fixed camber and planform. Here the code trims the sail twist to match the desired pressure distribution. Validation tests have been performed and results are presented. To validate the current approach, the pressure map was first computed from a specified shape. Then the resulting pressure distribution was employed as an input to the inverse method. The shape of the sail obtained with the inverse method is compared to the shape initially used in the analysis. The agreement is good in both inverse computations.
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