| 1. |
- Keller, H., et al.
(författare)
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Search for Forbidden Beta-Decays of the Drip-Line Nucleus Be-12
- 1994
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Ingår i: Zeitschrift fur Physik A Hadrons and Nuclei. - 1431-5831 .- 0939-7922. ; 348:1, s. 61-62
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Tidskriftsartikel (refereegranskat)abstract
- Beta-coincident gamma-rays have been measured from implanted pure samples of Be-12 separated at the LISE3 spectrometer at GANIL. An intensity of 0.040(26)% can be estimated for the branching ratio of the isospin forbidden pure-Fermi transition to the 0+ excited state of B-12 and of 0.008(6) % of the transition to the 1- excited state. Both are taken to represent upper limits. The halflife has been re-measured to be 26.1(2.4) ms.
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| 2. |
- Anne, R., et al.
(författare)
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Dissociation Reactions of the Be-11 One-Neutron Halo - the Interplay between Structure and Reaction-Mechanism
- 1993
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 304:1-2, s. 55-59
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Tidskriftsartikel (refereegranskat)abstract
- The angular distributions of the forward neutrons in the exclusive (Be-10 + n) channel have been measured. They can be accounted for quantitatively and without free parameters in terms of Coulomb and diffraction dissociation. The results show that the transverse momentum distributions result from an interplay between the tail of the wave function (the halo) and the reaction mechanism.
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| 3. |
- Anne, R., et al.
(författare)
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Exclusive and Restricted-Inclusive Reactions Involving the Be-11 One-Neutron Halo
- 1994
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 575:1, s. 125-154
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Tidskriftsartikel (refereegranskat)abstract
- Reactions of a 41 MeV/u beam of the radioactive halo nucleus Be-11 have been studied with a counter telescope coupled to an array of neutron detectors covering angles up to 97-degrees. The technique allows to determine single-neutron inclusive and exclusive angular distributions. The targets (Be, Ti and Au) were chosen to illustrate the relative roles played by nuclear and Coulomb mechanisms. The channels leading to Be-10, the dissociation channels, correspond to impact parameters larger than the sum of the radii of the target and the Be-10 core. It is shown that for the dissociation process it is possible to account almost quantitatively for the integral, single- and double-differential cross sections from models without free parameters including the Coulomb, Serber and Glauber (diffraction-dissociation) mechanisms. The neutron distributions from the nondissociative reaction channels show little individuality and it is convenient to group them together as the channel ''neutron plus anything different from Be-10''. We refer to these as ''restricted-inclusive'' reactions. These seem to be a promising tool for obtaining accurate information on the halo wave function in momentum coordinates.
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| 4. |
- HUDNER, J, et al.
(författare)
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PREPARATION OF YBA2CU3O7-X FILMS AND YBA2CU3O7-X/Y2O3 MULTILAYERS USING COEVAPORATION AND ATOMIC OXYGEN
- 1993
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 73, s. 3096-3098
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Tidskriftsartikel (refereegranskat)abstract
- Thin layers of YBa2Cu3O7-x (YBCO) deposited on LaAlO3 substrates have been prepared in situ by coevaporation of Y, Ba, and Cu. Incorporation of oxygen was accomplished by an atomic oxygen beam source with high cracking efficiency. The total oxygen flow at the substrate could be kept low enough to permit the use of a quadrupole mass spectrometer for evaporation rate monitoring. Films were strongly c-axis oriented with rocking curve full width at half-maximum values of 0.6-degrees. Transport measurements on patterned films yielded critical current densities of 6 x 10(6) A/cm2 at 77 K. The deposition method was demonstrated to be feasible for preparation of Y2O3/YBCO heterostructures.
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| 5. |
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| 6. |
- Spillmann, Dorothe, et al.
(författare)
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Characterization of a novel pyruvylated carbohydrate unit implicated in the cell aggregation of the marine sponge Microciona prolifera
- 1993
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 268:18, s. 13378-13387
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Tidskriftsartikel (refereegranskat)abstract
- The species-specific Ca(2+)-dependent reaggregation of dissociated cells of the marine sponge Microciona prolifera is mediated by a large extracellular adhesion proteoglycan. The glycans of this molecule are involved in the interactions of the proteoglycan with itself and with the sponge cells. Monoclonal antibodies against the glycans block the aggregation of sponge cells (Misevic, G. N., Finne, J., and Burger, M. M. (1987) J. Biol. Chem. 262, 5870-5877). Proteoglycan oligosaccharides were prepared by partial acid hydrolysis of the isolated glycans, and their reactivity with the monoclonal antibodies was monitored after linkage to phospholipid and immunostaining of thin layer chromatograms. One major antibody-reactive oligosaccharide was detected and purified by ion-exchange chromatography and high performance liquid chromatography. 1H NMR spectroscopy, fast atom bombardment-mass spectrometry, methylation analysis, and sequential chemical and enzymatic degradation studies indicated the structure [formula: see text] for the oligosaccharide. The depyruvylated derivative of the oligosaccharide did not react with the aggregation-blocking antibody, which indicates that the pyruvate acetal is an essential part of the epitope.
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| 7. |
- Gunnarsson, Thomas, et al.
(författare)
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An un-delooped version of algebraic K-theory
- 1992
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Ingår i: Journal of Pure and Applied Algebra. - 0022-4049 .- 1873-1376. ; 79:3, s. 255-270
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Tidskriftsartikel (refereegranskat)abstract
- Problems working with the Segal operations in algebraic K-theory of spaces-constructed by F. Waldhausen (1982)-arose from the absence of a nice groupcompletion on the category level. H. Grayson and D. Gillet (1987) introduced a combinatorial model G. for K-theory of exact categories. For dealing with K-theory of spaces we need an extension wG. of their result to the context of categories with cofibrations and weak equivalences. Our main result is that in the presence of a suspension functor-as in the case of retractive spaces-the wG. construction on the category of prespectra is an un-delooped version of the K-theory of the original category. In a sequel to this paper we show that Grayson's formula (1988) for Segal operations works as intended.
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