| 1. |
- Andersson, Jenny, et al.
(författare)
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Absence of the Lhcb1 and Lhcb2 proteins of the light-harvesting complex of photosystem II - effects on photosynthesis, grana stacking and fitness
- 2003
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Ingår i: The Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 35:3, s. 350-361
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Tidskriftsartikel (refereegranskat)abstract
- We have constructed Arabidopsis thaliana plants that are virtually devoid of the major light-harvesting complex, LHC II. This was accomplished by introducing the Lhcb2.1 coding region in the antisense orientation into the genome by Agrobacterium-mediated transformation. Lhcb1 and Lhcb2 were absent, while Lhcb3, a protein present in LHC II associated with photosystem (PS) II, was retained. Plants had a pale green appearance and showed reduced chlorophyll content and an elevated chlorophyll a/b ratio. The content of PS II reaction centres was unchanged on a leaf area basis, but there was evidence for increases in the relative levels of other light harvesting proteins, notably CP26, associated with PS II, and Lhca4, associated with PS I. Electron microscopy showed the presence of grana. Photosynthetic rates at saturating irradiance were the same in wild-type and antisense plants, but there was a 10-15% reduction in quantum yield that reflected the decrease in light absorption by the leaf. The antisense plants were not able to perform state transitions, and their capacity for non-photochemical quenching was reduced. There was no difference in growth between wild-type and antisense plants under controlled climate conditions, but the antisense plants performed worse compared to the wild type in the field, with decreases in seed production of up to 70%.
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| 2. |
- Howard, Martin
(författare)
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Usefulness in Representation Design
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation outlines a perspective in Human Factors in which artifacts play a central, but subordinate role. It lies at the intersection of (a) influences from information systems development, (b) an ecological approach to cognition, (c) practical problems faced by human factors design in complex systems, and (d) methodological inspirations from industrial design and ethnography.Central to this perspective is the notion of agent-environment mutuality and the perception-action coupling. The implications of considering cognition embodied and contextual on design are far reaching. It changes the nature of 'design problem' from an objective entitity to a relational property that needs to be examined from multiple perspectives. Methodological inspiration is borrowed from analytical ethnography to manage the issue of uncovering the practitioners' cognitive ecology, while influences from Scandinavian participatory design and scenario-based design are synthesized into a technique for managing envisioned fields of practice.As a result of this perspective, artifacts are used as tools of discovery and as hypotheses of usefulness. A technique called 'guided storytelling' is presented which allows designers and practitioners to jointly assess expectations of the impact of new technology on a field of practice. Examples of its use are presented which show its potential to uncover both opportunities for innovative design and shortcomings in our understanding of a field of practice.
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| 3. |
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| 4. |
- McCaddon, Andrew, et al.
(författare)
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Transcobalamin polymorphism and serum holo-transcobalamin in relation to Alzheimer's disease
- 2004
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 17:3, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Isoforms of the vitamin B<sub>12</sub> carrier protein transcobalamin (TC) might influence its cellular availability and contribute to the association between disrupted single-carbon metabolism and Alzheimer’s disease (AD). We therefore investigated the relationships between the TC 776C>G (Pro259Arg) genetic polymorphism, total serum cobalamin and holo-TC levels, and disease onset in 70 patients with clinically diagnosed AD and 74 healthy elderly controls. TC 776C>G polymorphism was also determined for 94 histopathologically confirmed AD patients and 107 controls. Serum holo-TC levels were significantly higher in TC 776C homozygotes (p = 0.04). Kaplan-Meier survival functions differed between homozygous genotypes (Cox’s F-Test F(42, 46) = 2.1; p = 0.008) and between 776C homozygotes and heterozygotes (Cox’s F test F(46, 108) = 1.7; p = 0.02). Proportionately fewer TC 776C homozygotes appear to develop AD at any given age, but this will require confirmation in a longitudinal study.
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