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- Amemiya, Chris T., et al.
(författare)
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The African coelacanth genome provides insights into tetrapod evolution
- 2013
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 496:7445, s. 311-316
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Tidskriftsartikel (refereegranskat)abstract
- The discovery of a living coelacanth specimen in 1938 was remarkable, as this lineage of lobe-finned fish was thought to have become extinct 70 million years ago. The modern coelacanth looks remarkably similar to many of its ancient relatives, and its evolutionary proximity to our own fish ancestors provides a glimpse of the fish that first walked on land. Here we report the genome sequence of the African coelacanth, Latimeria chalumnae. Through a phylogenomic analysis, we conclude that the lungfish, and not the coelacanth, is the closest living relative of tetrapods. Coelacanth protein-coding genes are significantly more slowly evolving than those of tetrapods, unlike other genomic features. Analyses of changes in genes and regulatory elements during the vertebrate adaptation to land highlight genes involved in immunity, nitrogen excretion and the development of fins, tail, ear, eye, brain and olfaction. Functional assays of enhancers involved in the fin-to-limb transition and in the emergence of extra-embryonic tissues show the importance of the coelacanth genome as a blueprint for understanding tetrapod evolution.
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| 3. |
- Lindberg, Staffan, et al.
(författare)
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Designing Collective Action: Problems of Local Water Management in Tiruchi District
- 2012
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Ingår i: Review of Agrarian Studies. - 2249-4405. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- A wide range of factors shapes irrigation institutions and collective action with regard to irrigation. They include the distribution of land across irrigation command areas and across classes, land tenure systems, access to new technology such as bore wells, the availability and cost of electricity and other energy sources for lifting groundwater, and, above all, state policies related to irrigation. Participatory irrigation management is hampered severely by policies in irrigation, such as the unregulated use of bore wells with free electricity provided by the state, that most benefit rich farmers. The paper, which is based on fieldwork conducted in Karur and Tiruchirapalli districts in Tamil Nadu in 1980 and in 2005, argues that the rapid and mostly unregulated development of well irrigation without any concomitant change in the legal framework and costing structure, and the lack of an objective basis for all water users to come together in collective action (given their different and often potentially conflicting interests), are the major causes for weakening collective action in irrigation management.
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| 6. |
- Venkatesh, L., et al.
(författare)
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Process parameter impact on microstructure of laser clad inconel-chromium carbide layers
- 2012
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. - 9783037852941 ; 702-703, s. 963-966
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Tidskriftsartikel (refereegranskat)abstract
- Chromium carbide based metal matrix composite (MMC) coatings are ideally suited for high temperature erosive-corrosive applications. Laser cladding of such MMCs, with Inconel as the ductile matrix instead of the usual NiCr alloy, has been attempted in the present study. The relative hardness of the laser clad layers was observed to drop with increase in laser power. The reduction in hardness was attributed to retention of lower amounts of chromium carbides in the clad layer at higher laser powers. Use of chemically assisted scans with electron diffraction allowed extraction of effective micro-textural information on the coatings. © (2012) Trans Tech Publications, Switzerland.
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| 7. |
- Viswanath, Venkatesh, et al.
(författare)
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Global regulatory burden for field testing of genetically modified trees
- 2012
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Ingår i: Tree Genetics & Genomes. - Heidelberg : Springer Berlin/Heidelberg. - 1614-2942 .- 1614-2950. ; 8:2, s. 221-226
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Tidskriftsartikel (refereegranskat)abstract
- Field trials are widely known to be essential for understanding the value and adaptability of trees produced via conventional and transgenic biotechnologies. However, obtaining permission for transgenic field trials is often considered to be very difficult in many countries. To understand the extent of regulatory requirements around the world and the burdens they impose, we surveyed 36 scientists and practitioners from 20 different countries who had experience or direct knowledge of regulatory compliance with field trials of transgenic trees. Results showed that permits and monitoring were universally required, and that public disclosure of field trial locations was required in three quarters of countries. Other major findings were that: separate approvals for different constructs, tree species, and trial locations were required in more than three quarters of the countries; characterization of each transgene insertion event was required as part of the application in four fifths of countries; and the application process itself was perceived as the largest single burden. Regulatory tiers that differentiate different kinds of transgenic trees based on perceived risk were present in only one fifth of countries. The data confirm the widespread perception among scientists that the costs and burdens of conducting field trials with transgenic trees are nearly universal substantial impediments to scientific and breeding progress.
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