| 11. |
- Mundy, Lee G., et al.
(författare)
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Protostellar Condensations within the Orion Ridge
- 1986
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 304:2, s. L51-L55
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Tidskriftsartikel (refereegranskat)abstract
- Aperture synthesis observations of the CS J = 2 to 1 line and 95 GHz continuum emission from a 2 arcmin x 3 arcmin region around IRc2 in the OMC-1 molecular cloud have been obtained at 7.5 arcsec resolution with the Owens Valley Radio Observatory millimeter interferometer. These observations reveal four distinct condensations with the OMC-1 molecular ridge. The condensations lie along the edge of the bright central part of the H II region, M 42, suggesting that they may have been formed as a result of shock compression driven by the H II region. Their masses and densities, M about 50 solar masses and n about 10 to the 6th - 10 to the 7th/cu cm, suggest that the condensations will undergo further massive star formation on a short time scale (about 20,000 yr).
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| 12. |
- Mundy, Lee G., et al.
(författare)
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Sonic linewidths in warm clouds?
- 1987
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Ingår i: Molecular clouds in the Milky Way and external galaxies. - Berlin/Heidelberg : Springer Berlin/Heidelberg. - 0387504389 ; , s. 235-237
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Konferensbidrag (refereegranskat)
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| 13. |
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| 14. |
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| 15. |
- Tang, G., et al.
(författare)
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Radio source structure from geodetic VLBI observations : evolution of the quasar 3C 345 at 8 GHz
- 1989
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 216:1-2, s. 31-38
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Tidskriftsartikel (refereegranskat)abstract
- Eight VLBI maps of 3C 345 were obtained at 8.3 GHz between 1980 and 1986. During this period, the two jet components C4 and C5 were shown to emerge from the core in succession and to move superluminally toward the west with angular velocities of 0.17 + or - 0.5 and 0.11 + or - 0.02 mas/yr, respectively. An emission detected between D and C5 after 1985.46 suggests that a new component emerged from the core, moving at an angular velocity of 0.2 mas/yr. The C3 component retained a velocity of about 0.44 mas/yr, and its proper motion was found to accelerate in the y-direction and decelerate in the x-direction.
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| 16. |
- Tang, Guoquiang, et al.
(författare)
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Radio source structure from geodetic VLBI observations : 8 GHz multi-epoch maps of the quasar 4C 39.25
- 1987
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 185:1-2, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- Techniques for estimating and/or eliminating the effects of structure variations in the extragalactic radio sources used as fiducial points in 8.3-GHz geodetic VLBI observations are described and demonstrated. Particular attention is given to the data base statistics, the calibration of visibility data, the production of hybrid maps with AIPS, and the implementation of these steps in a software package. A set of X-band maps of 4C 39.25, obtained with the receivers of the Mark III dual-frequency VLBI network at six epochs during 1980-1985, is presented. Such maps are shown to be of value (1) for maintaining submarcsec accuracy in the extragalactic reference frame and (2) for qualitative astronomical monitoring of the sources. In 4C 39.25, for example, apparent superluminal motions, complex internal kinematics, and a double western component are observed.
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| 17. |
- Waara, Sylvia, 1958-, et al.
(författare)
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Somatic hybridization between anther-derived dihaploid clones of potato (Solanum tuberosum L.) and the identification of hybrid plants by isozyme analysis
- 1989
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Ingår i: Theoretical and Applied Genetics. - Heidelberg : Springer Berlin/Heidelberg. - 0040-5752 .- 1432-2242. ; 77:1, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Green mesophyll protoplasts of the dihaploid potato line 198∶2 (Solanum tuberosum L.) were fused with herbicide-bleached mesophyll protoplasts of the dihaploid potato line 67∶9 using a polyethylene glycol protocol. Heterokaryons were identified under a fluorescence microscope using the dual fluorescence of carboxyfluorescein-stained, herbicide-bleached protoplasts and the autofluorescence of green mesophyll protoplasts. About 20% of the protoplasts survived the fusion treatment, and the fusion frequency was 3%-4%. Unfused and fused protoplasts were mass cultured for 6 weeks after which vigorously growing calli were selected and transferred to shoot regeneration medium. Somatic hybrids were identified by a combination of five isozyme markers, and the ploidy level was determined by flow cytometry. Out of 15 calli that regenerated shoots, 6 plants derived from 2 different calli were identified as hexaploid somatic hybrids, while one morphologically deviant plant from a third callus was identified as a mixoploid that had lost some enzyme markers after 4 months of culturing.
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| 18. |
- Weisner, Stefan E.B. 1954-
(författare)
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Factors affecting the internal oxygen supply of Phragmites australis (Cav.) Trin. ex Steudel in situ
- 1988
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Ingår i: Aquatic Botany. - Amsterdam : Elsevier. - 0304-3770 .- 1879-1522. ; 31:3-4, s. 329-335
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen concentration in basal stems of Phragmites australis (Cav.) Trin. ex Steudel was measured in situ, in monospecific stands. The mean O2 concentration in basal stems, and mean shoot length above water, decreased in deeper water. Oxygen concentration in basal stems was correlated to shoot length above water at a given water depth, and the mean O2 concentration in basal stems of shoots with similar length above water decreased in deeper water. The results suggest that O2 transport from shoots to below-ground parts is restricted in deep water by: (1) small shoot length above water; (2) long O2 transport distance. No influence of substrate redox potential on O2concentration in basal stems was found. © Copyright 1988 Elsevier B.V.
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| 19. |
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| 20. |
- Weisner, Stefan, 1954-
(författare)
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The relation between wave exposure and distribution of emergent vegetation in a eutrophic lake
- 1987
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Ingår i: Freshwater Biology. - Chichester, United Kingdom : Wiley-Blackwell. - 0046-5070 .- 1365-2427. ; 18:3, s. 537-544
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Tidskriftsartikel (refereegranskat)abstract
- Maximum water depth penetration and changes in horizontal distribution during 39yr of the emergent vegetation in Lake Krankesjon, S Sweden, were investigated. The capacity of the emergent vegetation to penetrate into deeper water areas was higher at wave exposed than at sheltered sites. Differences in biomass and biomass allocation of the dominant species, Phragmites australis, between an exposed and a sheltered site suggest that horizontal expansion towards deeper water at sheltered sites is limited by unfavourable substrate conditions.
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