| 1. |
- Beausang, C W, et al.
(author)
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Lifetimes of yrast and excited superdeformed states in Gd-150 : effect of particle-hole excitations on the deformation
- 1998
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In: Physics Letters B. - 0370-2693 .- 1873-2445. ; 417:1-2, s. 13-19
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Journal article (peer-reviewed)abstract
- The quadrupole moments and deformations have been measured for six superdeformed bands in Gd-150. The results indicate evidence for deformation driving properties of both the high-hi intruder and also low-N natural parity states at the superdeformed Fermi surface. Several new transitions have been identified and placed in the low spin non-yrast portion of one of the SD bands.
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| 2. |
- Svensson, C. E., et al.
(author)
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Observation and Quadrupole Moment Measurement of the First Superdeformed Band in the A~60 Mass Region
- 1997
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In: Physical Review Letters. - 1079-7114. ; 79:7, s. 1233-1236
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Journal article (peer-reviewed)abstract
- A high-spin rotational cascade of six gamma rays has been observed in Zn-62. The quadrupole moment of 2.7(-0.5)(+0.7) e b measured for this band corresponds to a deformation beta(2) = 0.45(-0.07)(+0.10). The properties of this band are in excellent agreement with calculations that predict high-spin superdeformed bands in Zn-62 with deformations beta(2) = 0.41-0.49. These results establish a new region of superdeformation for nuclei with neutron and proton numbers N, Z approximate to 30-32.
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| 3. |
- Svensson, C. E., et al.
(author)
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Smooth Termination of Rotational Bands in 62Zn: Evidence for a Loss of Collectivity
- 1998
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In: Physical Review Letters. - 1079-7114. ; 80:12, s. 2558-2561
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Journal article (peer-reviewed)abstract
- Two sets of strongly coupled rotational bands have been identified in Zn-62. These bands have been observed up to the terminating states of their respective configurations. Lifetime measurements indicate that the transition quadrupole moments in these bands decrease as termination is approached. These results establish the first terminating states of rotational bands in the A similar to 60 mass region and confirm the predicted loss of collectivity associated with smooth band termination.
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| 4. |
- Andersson, T., et al.
(author)
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High-spin States in the A=39 Mirror Nuclei 39Ca and 39K
- 1999
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In: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 6, s. 5-8
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Journal article (peer-reviewed)abstract
- High-spin states of the mass A = 39 mirror pair K-39 and Ca-39 were investigated via the fusion-evaporation reaction Si-28+O-16 at 125 MeV beam energy. The GAMMASPHERE array in conjunction with the 4 pi charged-particle detector array MICROBALL and neutron detectors was used to detect gamma rays in coincidence with evaporated light particles. The results of the first high-spin study of the T-z = -1/2 nucleus Ca-39 are discussed in terms of mirror symmetry and compared to spherical shell-model calculations in the 1d(3/2)-1f(7/2) configuration space.
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| 5. |
- Borcan, C, et al.
(author)
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First identification of excited states in the N = Z nucleus Br-70
- 1999
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In: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. ; 5:3, s. 243-246
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Journal article (other academic/artistic)abstract
- Excited states in the T-z = 0 nucleus Br-70 have been investigated using the reaction Ni-58(O-16,1p3n). gamma rays were detected with one EUROBALL CLUSTER detector and three single HPGe detectors. Charged particles and neutrons were registered with the Ro
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| 6. |
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| 7. |
- Clark, R M, et al.
(author)
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Superdeformation in bismuth
- 1996
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:1, s. 117-123
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Journal article (peer-reviewed)abstract
- High angular momentum states in Bi-195-197 are populated in two reactions: W-183(F-19,xn)Bi-202-x and Ta-181(Ne-20,xn)Bi-201-x at beam energies of 108 and 123 MeV, respectively. Gamma rays were detected using the Gammasphere array. Three weakly populated rotational sequences have been found. They each have properties characteristic of other superdeformed bands in this mass region. On the basis of cross-bombardment information we believe that one band belongs to each of Bi-195, Bi-196, and Bi-197. The properties of the bands in the odd-Bi nuclei are best reproduced if the odd proton occupies the favored signature of the [651]1/2 orbital, while the band in Bi-196 has this same proton configuration coupled to an additional N=7 (j(15/2)) neutron. The relative behavior of the J((2)) moments of inertia can be qualitatively understood in terms of Pauli-blocking effects.
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| 8. |
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| 9. |
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| 10. |
- Nisbet, R. M., et al.
(author)
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Primary-productivity gradients and short-term population dynamics in open systems
- 1997
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In: Ecological Monographs. ; 67:4, s. 535-553
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Journal article (peer-reviewed)abstract
- We present three models representing the trophic and behavioral dynamics of a simple food chain (primary producers, grazers, and predators) at temporal scales shorter than the scale of consumer reproduction, and at the spatial scales typically employed in field experiments. These models incorporate flexible behavioral responses of organisms to their predators and resources in spatially heterogeneous environments that are open to immigration and emigration. The basic models include passive immigration at all trophic levels, producer growth rates and losses to grazer consumption, grazer emigration rate as a behavioral response to producer and predator densities, grazer losses to predator consumption, and predator emigration as a function of grazer density. We model this system as: (1) a set of ordinary differential equations (''well-mixed model''); (2) a set of partial differential equations describing a population of discrete grazers foraging on discrete patches of primary producers (''discrete-grazer model''); and (3) a set of simulation rules describing the movement and foraging of individual grazers and the growth of primary producers on discrete patches in explicit space (''individual-based model''). The ordinary differential-equation models produced similar results to individual-based models with well-mixed producers, and the discrete-grazer and individual-based models produced similar results when grazers possessed a long-term memory of patch reward rates. The well-mixed and discrete-grazer models thus represent specific, limiting cases of the general individual-based model. Multiple equilibria and sustained oscillations are possible but are less likely in the discrete-grazer and individual-based models than in the well-mixed model, because localized foraging of discrete grazers leads to the rapid development of spatial heterogeneity in producer biomass and, hence, to a decrease in overall primary production. All models predict that stable equilibrium densities of all trophic levels increase with enrichment, provided grazers increase their emigration rates as predator density increases. If increasing predator density leads to decreasing grazer-emigration rates, predator and grazer densities increase, but producer biomass may increase or decrease with enrichment. These results contrast with predictions from models that assume ideal free distributions of grazers and/or predators with respect to their resources. Our models also predict that densities at all trophic levels will increase with increasing producer immigration, and that producer density will decline with increasing grazer immigration and increase with increasing predator immigration. Our qualitative findings on enrichment are used to interpret an experiment dealing with the short-term dynamics of a stream community open to grazers and predators.
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| 11. |
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| 12. |
- Svensson, C. E., et al.
(author)
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Decay Out of the Doubly Magic Superdeformed Band in the N=Z Nucleus 60Zn
- 1999
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In: Physical Review Letters. - 1079-7114. ; 82:17, s. 3400-3403
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Journal article (peer-reviewed)abstract
- The doubly magic superdeformed band in the N = Z nucleus Zn-60 has been identified. Linking transitions connecting this band to the yrast line provide the first spin, parity, and excitation energy measurements for superdeformed states in the A similar to 60 region. The stretched-E2 character and relatively large B(E2) values of these transitions suggest a nonstatistical decay-out process.
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| 13. |
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| 14. |
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| 15. |
- Wilson, Sara I, et al.
(author)
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Escape mutants of HIV-1 proteinase : enzymic efficiency and susceptibility to inhibition
- 1997
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In: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1339:1, s. 113-125
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Journal article (peer-reviewed)abstract
- Genes encoding a number of mutants of HIV-1 proteinase were sub-cloned and expressed in E. coli. The proteinases containing mutations of single residues (e.g., G48V, V82F, I84V and L90M) were purified and their catalytic efficiencies relative to that of wild-type proteinase were examined using a polyprotein (recombinant HIV-1 gag) substrate and several series of synthetic peptides based on the -Hydrophobic * Hydrophobic-, -Aromatic * Pro- and pseudo-symmetrical types of cleavage junction. The L90M proteinase showed only small changes, whereas the activity of the other mutant enzymes was compromised more severely, particularly towards substrates of the -Aromatic * Pro- and pseudo-symmetrical types. The susceptibility of the mutants and the wild-type proteinase to inhibition by eleven different compounds was compared. The L90M proteinase again showed only marginal changes in its susceptibility to all except one of the inhibitors examined. The K(i) values determined for one inhibitor (Ro31-8959) showed that its potency towards the V82F, L90M, I84V and G48V mutant proteinases respectively was 2-, 3-, 17- and 27-fold less than against the wild-type proteinase. Several of the other inhibitors examined form a systematic series with Ro31-8959. The inhibition constants derived with these and a number of other inhibitors, including ABT-538 and L-735,524, are used in conjunction with the data on enzymic efficiency to assess whether each mutation in the proteinase confers an advantage for viral replication in the presence of any given inhibitor.
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| 16. |
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